MWN Blog

Thursday morning update on today's potential severe weather

2012-05-31T08:35:00.000-05:00

The past couple of days (Tuesday and Wednesday), we've discussed the possibility of morning storms today that could "scrub" the atmosphere of instability and greatly reduce our chances of severe weather today. If you have looked outside, you see that that didn't happen. Here is the setup as of 7am this morning:

Weather setup for Thursday morning

Forecast models

Two clusters of storms are bypassing the region, with a trough and frontal boundary moving towards the area from the northwest as the day goes on. We'll be watching east AR for thunderstorm development late this morning that would affect the metro. Computer models are in two camps this morning. High-res models generally think that we'll see a round of storms early this afternoon out ahead of the front, with another potential round this evening as the front actually moves through around 9-10pm. The legacy models lean more towards a round of storms later in the afternoon with very little along the front that arrives later, closer to midnight.

Severe Weather Chances

As for our chances of severe weather, a Slight Risk is posted for the entire metro. The graphics below highlight the risk area as well as the probabilities of various severe weather types. Our primary threat will be damaging straight-line wind (a 30% chance of 58+ mph wind within 25 miles of your location over west TN and north MS), with a secondary threat of severe (1") hail. Given the lack of a favorable low level wind profile and barely-sufficient low level moisture, the tornado threat is hardly worth mentioning.

Severe weather graphics for Thursday

Mid-Southerners should be prepared for the possibility of strong to severe thunderstorms from lunchtime through the evening. Behind the front, MUCH cooler weather is expected Friday with highs only in the mid 70s. Lows Saturday morning will be in the 50s with highs again below normal (in the lower 80s) on Saturday.

MWN will provide nowcasting throughout the day on our social channels listed below. It's also a good time to pick up our mobile app for Android or iPhone with StormWatch+, which will alert you if your location is in the path of a severe thunderstorm.

Stay weather aware and have your umbrellas handy today! We could certainly use some rain!

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Slight risk for severe weather again on Thursday (updated)

2012-05-30T13:49:00.000-05:00

Wednesday, 8:15pm update:

It appears computer models are holding off on any early morning precipitation for the Mid-South. Given the information provided in the blog post immediately below, our confidence is increasing we will see some severe thunderstorms in and around the area beginning anytime after late morning. The most likely time will be during the afternoon and early evening hours. Though a tornado threat can't be completely ruled out, the primary threats with tomorrow's storms will be large hail and high wind. Storms should form into clusters or lines, which could heighten the straight-line wind threat.

MWN will provide nowcasting via social media throughout the event tomorrow. Now is a good time to arm yourself for the potential of severe weather with the MemphisWeather.net app with StormWatch+. StormWatch+ is our personalized severe weather notification tool that will warn the locations you input when severe weather threatens. Check it out now on iTunes/App Store or Google Play for Android.

Previous blog entry:

The Mid-South is under a Slight Risk of severe weather for Thursday. How the scenario plays out is the subject of this blog.

Another day has brought little clarification in exactly how tomorrow's weather scenario will unfold as the biggest factor in possible severe weather appears to be how overnight convection (storms) plays out to our west. What appears certain is that at least part of Arkansas will experience one or more mesoscale convective systems (MCS's) overnight that will move generally east and weaken as they approach the metro around dawn. These types of systems can have several effects on the weather downstream, both positive and negative, depending on their ultimate evolution. Some of this was hashed out in last evening's blog on the topic.

Multiple mesoscale convective systems (MCSs) traverse the Plains and Midwest (June 27, 2011)

Upstream MCS activity can bring extensive cloud cover or rain to an area as they fall apart during the early morning hours, thus providing a stabilizing influence and limiting renewed thunderstorms later in the day. The atmospheric disturbances (mesoscale convective vortices - MCV's) that linger following the demise of these systems also can bring a source of lift to a region that can reinvigorate storms when combined with sufficient heating and instability. Generally areas under the "fallout" of one of these MCS's as it weakens ends up with a greatly reduced chance of storms later in the day, while areas downstream of the "fallout zone" get the benefit of daytime heating (providing instability) and lift from the disturbance left behind by the decaying storm system upstream.

Satellite imagery at time of above radar image. Extensive cloud cover accompanies MCSs. After the MCS falls apart, the lingering cloud cover can hinder further convection later in the day.

We've seen both cases play out in the area, as well as the unmentioned case where the overnight convective system never weakens and comes through in a strong to severe state in the early morning hours. Right now, I don't really see that happening.

So, will the overnight storms die off over AR, leaving us with an unaffected "juicy" airmass capable of generating afternoon/evening severe thunderstorms? Or do we get the "fallout zone" - with morning clouds/showers and afternoon storms that fire off to our east? Time will tell... Either way, I think this will be our best chance for meaningful rain in some time.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Parts of the Mid-South in line for severe weather this afternoon

2012-05-30T12:59:00.002-05:00

At 11:30am, the Storm Prediction Center added parts of the Memphis metro to their Slight Risk zone for the possibility of severe weather, mainly for damaging wind and hail chances this afternoon. An hour later, a Severe Thunderstorm Watch was issued for north and central Mississippi and southeast Arkansas.

Convective Outlook - Wednesday, May 30. Slight Risk for MEM and points southwest

Severe Thunderstorm Watch until 7pm for much of north/central MS and southeast AR

Regional radar shows an area of thunderstorms, a few of which are severe warned in southeast AR, moving east into the watch box. Some of these thunderstorms could affect the immediate metro area by mid-afternoon, though the strongest storms will affect north MS, potentially including the metro counties.

Stay with MemphisWeather.net via social media for the latest developments as we nowcast throughout the afternoon. In addition, be sure to download the MWN mobile apps for Android and iPhone and then upgrade within the app to add StormWatch+ for personalized push notification weather alerts for your specific location. All links can be found below.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Arrival of a strong cold front will end heat (briefly)

2012-05-29T18:59:00.003-05:00

Memorial Day weekend was just as advertised, and as we have come to expect in the Mid-South - dominated by heat! With temperatures in the lower to mid 90s for the holiday weekend, the only minor relief was that the humidity was not off the charts, so heat index readings didn't quite reach 100. The heat continued today as we got within 1 degree of the record high for the date, topping out at 95.

The strong persistent high pressure responsible for the heat and lack of storms is weakening and moving east though, as a trough of low pressure replaces it. The trough will push a strong cold front through the region on Thursday. Ahead of the front, the Storm Prediction Center has initially placed the entire region under a Slight Risk for severe weather on Thursday (see graphic below).

For Wednesday, a few more storms may pop up than we have seen the past day or two as a weak cold front straddles the region. Dry conditions will persist one more day for most areas, even though increased cloud cover should hold high temperatures down into the lower 90s. On Wednesday night, strong to severe thunderstorms across the central and southern Plains will move east-southeast towards the Ozarks and eventually the Mid-South. These storms will be the fly in the ointment for Thursday as far as our severe weather chances are concerned.

Though the storms could be severe as they move across Arkansas Wednesday night, it is not unusual at all in this pattern for storms to be in a weakening state as they arrive in the metro, especially if it is near dawn, when the atmosphere is generally least conducive for severe weather. So, while they may bring some heavy rain and a few claps of thunder, many times this scenario produces showers and extensive cloud cover. The cloud cover then sticks around a good part of the day, outflow boundaries from the morning storms move by to the east of the area and, when afternoon and evening storms form along the cold front, they do so east of the immediate area and rob the region of not only a threat of severe weather, but some much-needed rainfall (the region stands more than a foot below normal rainfall amounts by this time of year).

Above is a graphic showing the GFS model's interpretation of the weather scenario at mid-day on Thursday. The positioning of the frontal systems and low pressure are good for possible severe weather, but if the precipitation the GFS shows well out ahead of the cold front materializes, our slight risk may be overstated. We'll see how later model runs handle the scenario. The best scenario for severe weather would be to have limited cloud cover in the morning with no rain and a primed atmosphere when the front comes through late in the day.

Behind the front, much cooler air will settle in for a couple of days. Friday's high will be only in the 70s with widespread 50s on Saturday morning. The cool-down will be brief, however, as strong summertime high pressure re-builds late in the weekend, bringing the mercury back up to the 90s by the start of next week!

However the severe weather scenario works out, you can count on MWN to be monitoring the situation and bringing you the latest via social media and the MWN Forecast. If you haven't yet downloaded the MWN app for iPhone or Android devices, now is a good time to do so. Be sure to activate StormWatch+ in the app so that you can be alerted when and if severe weather threatens your location!

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Drought worsens in the Mid-South

2012-05-24T10:25:00.000-05:00

In addition to early season heat and air quality issues, the Mid-South is also now beginning to see the effects of a lack of rainfall so far in 2012. For instance, the annual rainfall at Memphis International Airport so far for 2012 is 11.53", which is 11.51" (50%) below normal.

Below is the NWS-Memphis drought information statement, issued on Wednesday. The U.S. Drought Monitor now officially lists the metro area as being in a "Moderate Drought," a far cry from May 2010 and May 2011 when precipitation was well above normal.

...DROUGHT WORSENS IN THE MID-SOUTH...

SYNOPSIS...

RAINFALL HAS BEEN SPARCE THE LAST 60 DAYS OVER THE MID-SOUTH. MOST
COUNTIES RECEIVED 50 PERCENT OR LESS OF NORMAL PRECIPITATION.
OUTSIDE OF AREAS THAT RECEIVED AN INCH OR MORE OF RAIN THIS LAST
WEEKEND, MANY OTHER PLACES ARE IN DIRE NEED OF RAIN.

TEMPERATURES WILL RISE INTO THE 90`S THIS WEEK. THIS WILL MAKE THE
DROUGHT WORSE ALSO.

THE OUTLOOK IS LITTLE OR NO RAIN NEXT 5 DAYS AND BELOW NORMAL RAIN
THE REST OF THE MONTH.

OUTLOOK AND SUMMARY OF IMPACTS...

URBAN IMPACTS...EXPECT HIGH DRYING RATES, WITH YARDS EASILY USING
UP OVER 1/4 INCH OF TOPSOIL MOISTURE DAILY. MOST ALL YARDS ARE OR
WILL BE RUNNING SHORT OF WATER THE NEXT 5 DAYS. EXTENSION SERVICES
RECOMMEND PUTTING AN INCH OR MORE ON YARDS EVERY WEEK IN THIS
SITUATION.

AGRICULTURE IMPACTS...CORN, SOYBEANS, COTTON AND SORGHUM THAT WERE
RECENTLY PLANTED ARE STRUGGLING TO GERMINATE AND EMERGE DUE TO DRY
WEATHER. MANY WHO CAN IRRIGATE ARE WELL INTO THE ROUTINE TO TAKE
CARE OF CROP NEEDS. SOME WELL ESTABLISHED CROPS ARE ALREADY SHOWING
SIGNS OF MOISTURE SHORTAGES. DRY WEATHER THE REST OF THE MONTH WILL
DAMAGE SOME ROW CROPS. PASTURE CONDITION WILL DECLINE. HOWEVER,
CONDITIONS FOR HAY AND WHEAT HARVEST SHOULD BE NEARLY ALL EXCELLENT.

FOREST IMPACTS...FIRE DANGER IS NOW MODERATE OVER PARTS OF THE
MID-SOUTH. RIGHT NOW, THE DANGER IS GRASS FIRES WHICH SPREAD INTO
FORESTS. GRASS FIRES WILL BECOME EASIER TO IGNITE.

RIVER AND STREAM IMPACTS...CURRENTLY, FLOW OF RIVERS AND CREEKS
ARE MOSTLY WELL BELOW NORMAL WITH THE FLOW CLASSIFIED AS MODERATE TO
SEVERE HYDROLOGIC DROUGHT.

NEXT ISSUANCE DATE...ANOTHER DROUGHT INFORMATION STATEMENT WILL BE
ISSUED MAY 31 UNLESS UNEXPECTED WEATHER CHANGES WARRANT AN EARLIER
DROUGHT UPDATE.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Summer arrives just in time for Memorial Day weekend

2012-05-23T17:13:00.001-05:00

Mid-Southerners have gotten a treat over the last couple days when it comes to the weather, thanks to some cooler temperatures and lower humidity, making for some very enjoyable afternoons and evenings. However, as you might expect as we head towards Memorial Day weekend, this pleasant weather will soon be over. Get the sunscreen and swimming pool gear out because the heat takes over in the coming days with record temperatures looking increasingly likely by this weekend.

The heat begins to build on Thursday as highs return to the 90 degree mark, though humidity values will remain somewhat low keeping outdoor conditions from becoming too uncomfortable. That begins to change on Friday and especially over the weekend as highs reach the middle 90s and increasing humidity sends heat index values near the century mark for the first time in 2012. These temperatures will put high temperature records in jeopardy for at least Saturday and Sunday, and possibly Monday (Memorial Day) as well. Low temperatures will also be near record warm levels, as numbers only bottom out in the mid-70s, especially in the Memphis “heat island.”

So what will cause this stretch of heat? A building high pressure ridge at the mid and upper levels of the atmosphere will set up directly over the region, creating a “dome” of heat that will cover much of the Southeast U.S., but especially the Mid-South. This high pressure ridge will block any rainfall or significant cloud cover from developing, allowing the heat to continually build through the weekend. A high pressure ridge of this strength normally isn’t a factor in our weather until the middle of summer, thus the near-record temperatures we are expecting.

As depicted by the GFS model - the high pressure "heat dome" will park itself over the Mid-South for the weekend.
Active weather will be hundreds of miles away.

In addition to the heat, the stagnant pattern the high pressure ridge will produce may also create poor air quality issues. As winds remain light this weekend, the atmosphere will not be able to “mix out” various pollutants that build up through the day. As a result, more “Code Orange” days will be possible, particularly on Saturday, Sunday, and Memorial Day. That may make prolonged outdoor activities in the afternoons and early evenings unhealthy, especially for those with respiratory diseases like asthma.

Fortunately, there is some hope for relief in the foreseeable future. It appears the high pressure ridge will begin to break down late on Memorial Day but especially Tuesday into Wednesday as a new storm system and associated cold front begin to approach from the west (see graphic below). This should allow for increasing clouds, some rain chances, and slightly cooler temperatures to filter back into the area for the middle of next week.

NWS surface weather forecast for next Tuesday

With hot weather arriving just in time for Memorial Day weekend, and many of you likely planning outdoor events, be sure to plan appropriately for this early bout of summer heat. You can find a few heat-related safety tips in this MWN Blog post.This is particularly true given the possibility of poor air quality. You can learn more about poor air quality and it's effects on sensitive groups, as well as find additional links in this previous MWN Blog post. MemphisWeather.Net will keep you updated over the next several days, including passing along any air quality alerts that are issued.

--Kevin Terry, MemphisWeather.Net

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Views of the annular solar eclipse - May 20, 2012

2012-05-21T21:27:00.001-05:00

Last night (Sunday, May 20), many parts of the U.S. were treated to an annular solar eclipse, or part of it (known as a partial eclipse). We pulled a few images of the eclipse from a variety of sources and placed them below.

Slooh (events.slooh.com) maintained a live video feed throughout the event from a couple of western U.S. locations where the annular eclipse would be best viewed. A couple of screenshots of their feeds are shown below.

The above was taken as Slooh's site in California experienced the "ring of fire," in which a ring of the sun is apparent around the moon.

The second shot was taken in New Mexico. Note the orange ring of the sun surrounding the black disk that is the moon.

Locally, a partial eclipse was photographed from the Mississippi River bluffs. Photo credit: Austen Onek

The TX panhandle was the prime viewing spot for the eclipse as the sun set during the annular phase. Photo credit: Greg Jackson (NWS Midland, TX).

The next major solar eclipse event is a total eclipse which will occur across a wide swath of the U.S. in 2017. Expect a lot of press and hoopla leading up to this event as a total eclipse visible in the U.S. is rare! For more on this particular event, check out our recent blog post leading up to the eclipse.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Solar eclipse to be viewable by Mid-Southerners on Sunday

2012-05-18T18:23:00.003-05:00

On Sunday, May 20, an annular eclipse of the Sun will be visible within a narrow corridor along Earth's northern Hemisphere, beginning in eastern Asia, crossing the North Pacific Ocean, and ending in the western United States. However, much of North America, including the Memphis metro, will be able to view a partial solar eclipse just before, and as, the sun sets for the evening. This eclipse marks the first annular eclipse visible in North America since May 1994. The last total solar eclipse visible in the contiguous 48 states was in 1979. The next is a highly anticipated event in 2017.

Red area indicates where the annular eclipse can be viewed. Credit: NASA GSFC

The specific for Memphis:
- Partial eclipse begins: 7:28pm
- Partial eclipse ends: 8:00pm (sunset)
- Degree of obscuration: 33% (1/3 of the sun will be eclipsed)

A picture of an annular solar eclipse taken from space by the joint Japanese-American Hinode satellite on Jan. 4, 2011.
Photo credit: Hinode/XRT.

A solar eclipse occurs when the new moon passes between Earth and the sun, blocking out a portion of the sun from viewing. A total eclipse is when the sun is completely blocked by the moon. An annular eclipse, like this one, is when the moon passes directly in front of the Sun, but does not completely obscure it, creating a "ring of fire." The annular eclipse will only be viewable along a relatively narrow path described above. Those around that path will be treated to a partial eclipse, in which a "bite" appears to be taken out of the sun.

Partial solar eclipse

We remind you that you should NEVER look directly at the sun, even during an eclipse, as you risk serious and permanent eye damage or blindness. There are several suggestions for viewing an eclipse on the Exploratorium website. These include putting a pinhole in one piece of cardboard, then projecting the light through the pinhole onto another sheet of white cardboard. Or, you can also try looking at the ground underneath a leafy tree. The gaps between the leaves will shine on the ground in the shape of the sun!

Remember that the event will occur just before sunset, so viewing may be difficult. Just remember NOT to look directly at the sun! There will be plenty of cool pictures on the internet late Sunday evening and Monday for you to check out! In the meantime, we'll cross our fingers that sky conditions will permit optimal viewing. Overcast conditions are currently not expected, though a partly cloudy sky is.

A video by NASA explains this impressive event in more detail.
Complete detail on this eclipse, also by NASA, can be found here.
Here is a map of the western USA showing where the annular eclipse will be seen completely.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Mother's Day weekend forecast - not exactly what momma deserves!

2012-05-11T17:08:00.001-05:00

Lots of activities going on this weekend, even though Memphis in May has no major outdoor festivities planned. There still is Greek Fest and, of course, Mother's Day. We all know our mothers deserve the very best because without them, we wouldn't be here! Unfortunately, the weather is not going to be all that cooperative, so pick a restaurant that doesn't make it's "wait list" stand outside! The only potential good news out of the weather pattern is that it won't be hot and it won't be severe!

Telltale clouds moved overhead today, indicating an approaching weather system. These clouds are ahead of a weak surface low that will move from the western Gulf Coast to the southeastern U.S. by Sunday. It is accompanied by an upper level low that will also affect the area. Precipitation amounts this weekend won't be off-the-charts, but everyone should get a beneficial rain in the 24 hours between mid-day Saturday and mid-day Sunday. Average amounts should be somewhere in the 1" range during that time frame.

Low pressure over TX is sending clouds across the Mid-South today. The low will be responsible for rain chances this weekend.

As for exact timing, a few of the computer models finally started coming into agreement today and it appears that, while a few showers are possible as early as Saturday morning, the bulk of the rain will hold off until late morning, though it will remain showery and intermittent through afternoon. By evening, the main "slug" of moisture will move over and steady rain is likely Saturday night. By Mother's Day morning, steady moderate rain should be tapering off, though we expect to see light showers stick around much of the day as the upper low moves near. All rain should be done by Sunday evening, leading into a dry work week with moderating temperatures. Very little thunder is expected with this system as it moves by to our south, keeping the instability and deeper moisture suppressed towards the Gulf Coast. Flooding is also not expected to be an issue with only 1" or so of rain spread over a 24-hour period.

GFS model precip amounts through Sunday evening. Memphis is the black dot near center. MWN forecasts ~1" of rain this weekend for the metro.

Highs this weekend will be mainly in the mid 70s owing to the showers and cloud cover. Overnight lows will be mild - near 60 or slightly higher. Next week, we'll see highs rise from near 80 early in the week to perhaps the upper 80s by week's end. For the complete forecast, visit the MWN Forecast page on MemphisWeather.net.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Monday front brings t’storm chances, then a pattern change!

2012-05-06T15:07:00.000-05:00

Summer has seemingly arrived early to the Mid-South this past week, as temperatures reach the 90 degree mark and that classic Memphis humidity makes its first of many appearances in the months to come. Fortunately, summer’s early arrival looks to be short-lived, as a potent May cold front will make its way to the Mid-South on Monday. The front will be accompanied by showers and possibly strong thunderstorms, but then a significant pattern change is in the offing for much of the upcoming week.

A few showers may approach the metro area toward dawn Monday, but rain chances will increase significantly as daytime heating increases and the front pushes east through Arkansas, approaching the Mississippi River during the evening hours. Scattered to numerous showers and thunderstorms are expected, possibly in a couple of separate rounds between Monday morning and evening.

NAM forecast model for late Monday afternoon.

With strong instability and some modest wind energy along the front, the potential does exist for a few thunderstorms on Monday to be strong to severe. The Storm Prediction Center has placed the entire region in a “Slight Risk” for this threat (see graphic below). The main hazard is strong, possibly damaging straight-line winds, with a secondary threat of hail. The tornado threat is very low. Thunderstorms may also produce torrential downpours, which will hopefully bring some much needed rainfall to the area, without significant severe weather.

Storm Prediction Center severe weather outlook for Monday.

The cold front will be slow to clear the region, but should do so Tuesday morning, taking any lingering showers with it. Behind the front, get ready for a stretch of outstanding weather that may last right through next weekend! High temperatures will hold near or below 80 for several days, with numbers falling into the 50s overnight. Additionally, humidity levels will fall back into a very comfortable range!

Stay with MemphisWeather.Net for the latest on Monday's thunderstorm chances. As needed, we'll be nowcasting during the day via our social media feeds (see links at the bottom of this post). Also, don't forget our StormWatch+ service that will immediately notify you on your smartphone to any severe weather alerts issued. For more, visit StormWatchPlus.com.

--Kevin Terry, MemphisWeather.Net

April 2012 Climate Data and MWN Forecast Accuracy

2012-05-03T16:57:00.001-05:00

Following the 7th warmest meteorological winter (December-February) on record and the warmest March on record, April continued the well-above-normal temperature trend, though it was not warm enough to reach the "Top 10" Aprils temperature-wise. However, a "bottom 10" was recorded as rainfall was hard to come by in one of the typically wetter months of the year. With just over an inch of rain at Memphis International for the month, this month became the second driest in recorded history. The lack of rain is a far cry from the past two years when record flooding was found regionally heading into early May!

Memphis International Airport, Memphis, TN
The average temperature for the month of April was 66.0 degrees, 3.1 degrees above normal. The average high temperature was 76.5 degrees and the average low was 55.5. The coolest temperature of the month was 43 degrees on the 12th and 22nd, while the highest temperature was 86 degrees reached on the 28th and 30th. There were 11 days in which the high reached 80 degrees or higher and 8 days in which the average daily temperature was 10 degrees or more above normal.

Precipitation for the month totaled 1.04", which was 4.46" below average. There were only 6 calendar days with measurable rainfall, none of which had more than 0.35". The maximum 24-hour amount was 0.40" on the 15-16th. The peak wind gust was 41 mph (from the south) on the 15th with an average wind speed for the month of 8.5 mph. Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions, Bartlett, TN
The average April temperature at Cirrus Weather Solutions in north Bartlett was 65.4 degrees with a maximum of 88.8 degrees on the 1st and a minimum of 34.9 degrees on the 12th. April precipitation totaled 1.44" in the automated gauge. A co-located manual gauge used for the CoCoRaHS program measured 1.47". The peak wind gust was 26 mph on the 15th. Average relative humidity was 63%. Click here for a daily recap on MemphisWeather.net.

MWN Forecast Accuracy
For the month of April, the average temperature error in all MWN temperature forecasts was 2.11 degrees. Over 57% of the MWN temperature forecasts for the month were within 2 degrees of the actual temperature. MWN's forecasts extend out five periods (or 2.5 days). For dewpoint accuracy, the MWN forecast averaged 2.49 degrees of error and fell within 2 degrees of the actual dewpoint nearly 62% of the time. Historical accuracy statistics can be found here.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

One-year anniversary of the Super Outbreak of 2011

2012-04-27T19:13:00.001-05:00

Today marks the one year anniversary of the 2011 "Super Outbreak" - the largest outbreak of tornadoes since April 3-4, 1974. While the Memphis area wasn't directly affected by any of the tornadoes that day, April 27 was the last in a 3-day onslaught of severe weather that affected the southeastern U.S. (Actually, severe weather continued to a much lesser extent into the Mid-Atlantic on the 28th as well.) During that string of days, the metro received severe weather in the form of flooding, large hail, wind damage, and a couple of rotating supercells that prompted tornado warnings but no touchdowns.

We'll take the opportunity to recap exactly what happened those three days, focusing especially on April 27 and the Smithville, MS tornado - the only tornado to affect the NWS-Memphis warning area. We'll include lots of links that have exceptional information on the outbreak as well. The first graphic below is the Storm Prediction Center's long-range outlook issued on April 23. Even that early, there was a sense that this period could bring a severe weather outbreak with long-track and violent tornadoes.

SPC's long-range outlook issued on April 23 indicated potential severe weather on April 26-27

A summary of all severe weather reports from April 25-27 received at the NWS-Memphis office

April 25, 2011

The day started with a moderate risk of severe weather over southwest TN, northwest MS, and southern AR. Multiple waves of storms, one at mid-day that prompted Tornado Warnings in the metro and another late in the evening that formed into a squall line, brought many reports of severe weather. There were no confirmed tornado touchdowns in the metro, however a couple of funnel clouds were reported with the mid-day storms. The evening squall line hit between 10-11pm and caused some straight-line wind damage. Much of the day's severe weather occurred in the ArkLaTex near where low pressure was moving along a stationary front that was draped across the southern Plains into the Mid-Mississippi Valley, while wind reports also lined up from NE Arkansas into central KY.

April 25 morning SPC outlook overlaid by preliminary storm reports

Storm reports received by NWS-Memphis on April 25 - not all were confirmed

April 26, 2011

The day started with another moderate risk of severe weather over the entire Mid-South area, but by mid-morning the metro area was upgraded to a rare “high” risk signaling the potential for a major severe weather and tornado outbreak. By mid-afternoon, supercell storms exploded over central Arkansas and moved northeast toward the metro, prompting numerous Tornado Warnings through the evening hours. Though no tornadoes were confirmed locally, there were many areas of straight-line wind damage and hail, along with funnel clouds. As the storms began to congeal into several storm clusters and squall lines that continued into the overnight hours, widespread flash flooding began to develop. The majority of the tornadoes on this day occurred in northern Louisiana near a secondary area of low pressure.

April 26 morning SPC outlook overlaid by preliminary storm reports

Storm reports received by NWS-Memphis on April 26 - not all were confirmed

April 27, 2011

The most prolific day of the outbreak began with an initial round of tornadoes that caused damage and fatalities in Mississippi and Alabama during the early morning. Meanwhile, in the metro, the repeated showers and thunderstorms continued to exacerbate flooding conditions for the next several hours. Another rare high risk area had been issued, this time centered on northern Alabama, while the metro was within the slight to moderate category. Clearing skies during the late morning to early afternoon allowed an already volatile airmass over the entire Southeast to become even more dangerous and soon new supercell storms were exploding, first in MS and then AL. Many of these cells would grow into monsters, producing some of the most violent tornadoes of recent memory, and tornadoes would continue well into the night across Georgia, east Tennessee, and even up the Appalachian chain as far north as New York, leaving many towns devastated and many lives lost. By great fortune, the Memphis metro escaped this most violent round of weather almost entirely, with only a few storms with isolated hail, though tornadoes did touch down as close as Jonesboro, AR and Oxford, MS. A loop of regional radar for the entire day (caution: large file) assembled by UA-Huntsville grad student Cody Kirkpatrick can be viewed here.

April 27 morning SPC outlook overlaid by preliminary storm reports

"Rotation tracks" for April 27, 2011 - tracks of storms that were rotating (not necessarily producing tornadoes)

Storm reports received by NWS-Memphis on April 27 - not all were confirmed

The most devastating damage closest to Memphis on the 27th was in Smithville, MS, about 130 miles southeast of the Bluff City. At 3:45 in the afternoon, and for the first time since 1966, an EF-5 tornado struck the state of Mississippi and literally leveled this small town. According to the National Weather Service, peak wind reached 205 mph and the tornado width in the Smithville area was 1/2 mile. The tornado's path started just southwest of Smithville and continued for over 35 miles into northwest Alabama. A total of 17 persons lost their lives in Smithville with an estimated 40 injured. The post office, police station, and water and sewage systems were destroyed and several other businesses, mostly on Highway 25, or Main Street, were severely damaged.

The following pictures were taken by MWN meteorologist Erik Proseus 3 months after the Smithville tornado, following the debris clean-up effort but before much re-building began.

In all, the following sobering statistics were collected (all stats from NOAA):

April 2011 tornado count: 758 (most active month ever, beating May 2004 [542])
More than 200 tornadoes in 5 states from April 25-28
Fifteen violent (EF-4 or EF-5) tornadoes
Eight tornadoes with path lengths of 50 miles or longer
Two tornadoes that each killed 60 or more
321 people killed from April 25-28, 316 on April 27 (4th most in one day), and 360 for the month
Of the 316 deaths on April 27: 31 were in MS, 234 in AL, 32 in TN, 15 in GA, and 4 in VA
More than 2,400 injuries
Total damage: over $4.2 billion
All fatalities occurred in areas where tornado warnings were in effect
Mean tornado warning lead time (from when tornado warning was issued until tornado touched down) was 22.1 minutes

Links from NOAA and the National Weather Service:

Links from other sources:

Wikipedia article on the April 25-28 tornado outbreak
"A look back: Aftermath of the Smithville, MS EF-5 Tornado" - MWN Blog (July 29, 2011)
"Smithville: One Year Later" - WTVA, Tupelo MS
"10 Seconds of Terror" - Commercial Appeal special article (Oct 2011)
"James Spann, TV weatherman, fears his effort during April 27 tornadoes wasn't good enough" - Birmingham News (AL.com)
"A Defining Day" - James Spann retrospective on April 27
"Memories of April 27, 2011 – My Storm Chase Account" - Mike Wilhelm, Huntsville, AL
An hour-by-hour account of the events of April 27 in AL - Poignant recount from AL.com

There are many other accounts, stories, pictures, video and reflections on the web. These are just a few of the highlights. As we remember those that perished, their loved ones, and the countless others whose lives were affected in many ways, MWN encourages you to use this time to re-focus on preparedness. While this particular event may have been a once-in-a-lifetime or generational outbreak, it doesn't take 10 or 100 or more tornadoes to affect you. It only takes one, in the wrong place at the wrong time.

Memphis is a part of what is called "Dixie Alley" - the area of the country that is the deadliest during severe weather. Know your plan, practice it, and share it with family. Have a plan for home, work, school, or wherever else you frequent, including on the road. Include in your plans multiple ways of receiving severe weather information, especially at night or away from home. The MWN Storm Center has more information and safety tips that you should review with your family. Our prayer is that everyone is properly prepared for severe weather and that nothing remotely close to April 27th occurs again in our lifetimes.

--Erik Proseus/Kevin Terry

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Warm temperatures are back, but what about rain chances?

2012-04-25T15:36:00.001-05:00

Welcome to MWN Blog post #950!

After a stretch of below normal temperatures for the last few days in the Mid-South, the warmth came back in a hurry over the last 24 hours as strong and gusty southwest winds sent the numbers back above the 80 degree mark, with much higher humidity levels returning as well. It looks as if the warmer weather will be sticking around a while, but is there any significant rainfall chances in the offing as the Memphis area now approaches an 8-inch rainfall deficit for the year?

While a few weak systems have brought isolated to scattered rainfall to the area over the last several weeks, the last significant and widespread rainfall (greater than an inch) was way back on March 16! This pattern is in sharp contrast to one year ago this week, as a multi-day historic severe weather outbreak and flooding event began to unfold across the Mississippi Valley and Southeast U.S.

Looking ahead, a cold front will be approaching from the north on Thursday. Unfortunately, the cold front looks to stall just north of the area, meaning the best rain chances may again avoid the metro area. Nevertheless, as the front makes it closest approach late Thursday afternoon through Thursday night, a few thunderstorms may develop and drift into parts of the area, with those north of I-40 having the best risk of seeing rain. Still, significant and widespread rainfall is not expected during this period.

WRF Model for Thursday evening. Scattered t'storms will likely be ongoing near front, with best chances north of Memphis metro.

This front will meander north of the area through Friday and Saturday, likely keeping conditions dry here though an isolated risk for a shower or storm remains. The front will make another push into the area on Sunday, and models are showing a bit more progress on this attempt, meaning our best rain chances arrive then with scattered showers and thunderstorms possible. However, it again doesn’t appear to be shaping up to be an event that will put a major dent in the growing rainfall deficit.

NWS weather forecast map for Sunday morning, with near-stationary front close to metro, bringing our best rain chances.

Finally, in a reversal from thinking a few days ago, this front then looks to lift back north of the region at the start of next week. This means a cooldown earlier thought possible appears off the table, with temperatures for the next seven days reaching the 80s and mild overnights expected as well. More scattered rain chances may enter the picture around next Tuesday and Wednesday, but we may be waiting for next widespread one-inch or greater rainfall event for a while longer.

Stay with MemphisWeather.Net for the very latest on rain chances in the days ahead. You can find the full and updated forecast details on MWN's forecast page.

--Kevin Terry, MemphisWeather.Net

Outdoor warning sirens - part 3: the warning process and future of severe weather warning systems

2012-04-19T20:53:00.001-05:00

This part of the series is a long time coming, but here it is!

In the first two posts of this series on outdoor warning sirens, we examined the role of the Emergency Management Agency during severe weather (including the activation of warning sirens) and the role of outdoor warning sirens themselves, which was to warn people who were outdoors of adverse weather. In this post, the final in our 3-part series, we take a look at the future with regards to dissemination of severe weather warnings.

Background on the current warning process

In 2007, the NWS changed policy with regards to issuance of Tornado, Severe Thunderstorm, and Flash Flood Warnings to one based on the actual area threatened versus alerting entire counties. The NWS draws storm-based warnings, or "polygons," to highlight the expected path of the storm, with little regard for political boundaries (see the example from March 15, 2012 below). This policy change had several intentions, one of which was to limit the area being warned, thereby hopefully reducing the perceived false alarm rate created by warning an area that the NWS is fairly certain will not be affected.

A Severe Thunderstorm Warning polygon ("storm-based warning") that identifies a small section of eastern Fayette Co. and a larger portion of Hardeman Co. as having a threat of large hail and damaging wind. There is no threat of severe weather in Moscow or Middleton, even though there is in other parts of their counties.

Unfortunately, some 5 years after changing to storm-based warnings, NOAA Weather Radios, many outdoor warning siren systems, and even some local broadcaster's warning plotting software - the top 3 ways that citizens get severe weather information - still alert based on the COUNTIES affected, rather than the actual AREA affected. In the example above, the storms are moving northeast and, based on the yellow polygon, there is no threat to Moscow, Macon, or Middleton. However, for those with Weather Radios in those locations, the alert tone would sound for all three towns.

Another example is below - this one even closer to home for many of you. A Tornado Warning was issued shortly after 10pm on January 22, 2012 for southern Shelby County and northern DeSoto County. A squall line (not depicted) was approaching the river and a possible tornado was detected in the portion of the line that would affect the areas inside the red box. Sirens sounded and weather radios alerted across Shelby County (excluding DeSoto County for this example). Except for the southern part of the city and the eastern suburbs, there was no imminent threat from a tornado. It could be said that although the NWS intended to only warn 242 sq. mi. of Shelby County, the sirens and weather radios ended up warning 754.5 sq. mi. or more than three times the area. (In this example, there was sporadic wind damage reported, including a 105 mph gust that lifted a large roof from a commercial structure, all within the confines of the warned area.)

Outdoor warning sirens and the polygon warning

Now that the warning process is better defined, what is the future of weather warning dissemination? Perhaps from these examples you can already start to see it: storm-based warning dissemination, rather than county-based. While NOAA Weather Radio and some progressive county governments are beginning to make strides in this area, it will be some time before these systems are fully taking advantage of the benefits of the current storm-based warning program.

In Shelby County, TN, EMA Director Bob Nations indicates that they are "taking a serious look at new technology" and "exploring all the options" as they work towards system upgrades mandated by the Federal Communications Commission (FCC). The FCC program, called "narrowbanding," opens up additional radio frequencies by essentially squeezing all of the current frequencies closer together in the radio spectrum. Narrowbanding will require a significant purchase of new hardware or upgrades to current infrastructure to meet a federally mandated January 1, 2013 deadline. How does this affect the siren program? The sirens are activated by radio frequencies that will change under the narrowbanding program.

Part of the infrastructure upgrade will include new siren controllers on 111 warning sirens under the purview of the City of Memphis, which will be replaced with equipment that allows individual sirens to be sounded should a change in siren policy be made. In addition to hardware, new storm-based warning software would also be required to activate individual, or banks, of sirens. Nations is quick to point out that, while a change to siren policy might be possible with the new infrastructure, there would have to be agreement from policymakers who may not be willing to take the risk of storms remaining within the warned area. Any changes to public policy will require the approval of those who write the policy. Due to potential liability issues, any change to the current methodology of warning the entire county "would have to work every time," according to Nations.

So while (and until) the infrastructure upgrade and public policy process plays out (should there be a decision to move in that direction), citizens are strongly encouraged to consider all means of protecting themselves in the event of severe weather. As discussed in part 2 of this blog series, outdoor warning sirens are not the "end all, be all" and are simply not designed to alert you if you are anywhere but outdoors, no matter what strategy is employed to sound them.

The future of weather warning systems

The best solution is that we move to faster-pace, more technological solutions that are available today. With the preponderance of smartphones and the capability of these devices to use GPS to determine your precise location, it's no wonder their worth in targeted warning information is being utilized more and more. There are several mobile apps that are available to warn you, in your specific location, to the threat of impending weather. Of course, we highly recommend ours, but any will likely fit the bill depending on the features you are looking for.

The MemphisWeather.net app for Android and iPhone includes StormWatch+, a push notification system that will warn the user of severe weather watches and warnings that are issued for 2 pinpoint locations of their choosing. It includes an audio alert that is loud enough to wake you up at night provided the phone is nearby and not silenced. There are other services available as well, including some phone services that will call your registered numbers should severe weather threaten.

It is vitally important that you have multiple ways of receiving severe weather information, for your location if possible (or for your county if not), that will alert you at any time of day or night. Outdoor sirens are one way, but they CANNOT be the only way. NOAA Weather Radio is highly recommended as the baseline, but for even more pinpoint warnings that take advantage of the storm-based warnings issued by the NWS, you should add another service like StormWatch+ to your severe weather toolkit. Severe weather can strike in any month and at any time of the day in the Mid-South. "An ounce of prevention is worth a pound of cure."

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or follow us on Facebook or Twitter.

Mid-South storm chasers injured while providing aid

2012-04-15T17:21:00.001-05:00

Storm chasers Brandon Bridges (standing) and Vincent Webb after a scary interstate accident.
Photo courtesy Vincent Webb.

On their way back from a day of chasing in the Plains, in which they videoed at least one tornadic storm, Mid-South storm chasers Vincent Webb and Brandon Bridges were struck by a vehicle on I-40 near Fort Smith, AR on Sunday afternoon, April 15.

Webb (@msstormchasing on Twitter) and Bridges (@bbridges18) were traveling in Webb's storm chase vehicle on I-40 with Jeremy Johnson (@memphisjdj) and Nick Hellums (@midsouthchasers) on their way back to the Memphis area and reached a stretch of I-40 that had experienced showers. They encountered a rollover accident on the opposite site of the interstate and pulled over to offer assistance. After crossing the interstate by foot, Bridges and Webb were helping the motorist in the rollover vehicle when another vehicle hydroplaned and careened towards the scene. Both Bridges and Webb tried to get out of the way, but were struck by the approaching vehicle and thrown several feet into the grass along the interstate. Johnson and Hellums were bystanders and not injured. Both Webb and Bridges were transported to the hospital for precautionary purposes with minor injuries. Their chase vehicle, owned by Webb, was on the opposite side of the interstate and not involved.

I spoke with Bridges by phone Sunday afternoon and he indicated that their injuries were minor and he hoped that they would be back in the Memphis area very late tonight.

Following the recent death of storm chaser Andy Gabrielson, we are again reminded that the storms themselves are only one threat chasers face as they attempt to provide a service to the community and the National Weather Service by providing reports of severe weather that aid in the protection of life and property. Frequently, as in this case, they are "first responders" on the scene after disaster strikes and are always ready to call off the chase to provide assistance wherever required. Please keep all of these chasers in your prayers.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

UPDATED: Details on potential severe weather threat overnight

2012-04-15T17:01:00.001-05:00

UPDATES AS OF 9:15PM ARE POSTED BELOW IN RED.

Following yesterday's Central Plains severe weather outbreak, Mid-Southerners are a little uneasy about the threat here as the same storm system makes it's way through the region tonight. Fortunately for us, the impressive dynamics that spawned nearly 100 tornado reports (at last count, that number will likely fall a little as reports are verified) on Saturday are much weaker and will be well-removed from this portion of the country as the system moves east. However, a potent cold front will still push a line of storms through the region during the overnight hours.

Reports of severe weather in the Plains on Saturday, April 14, 2012

The Storm Prediction Center has placed western sections of the Mid-South under a Slight Risk for severe weather this evening and tonight (updated graphic below). This is due to strong to severe thunderstorms, some with damaging wind and hail threats, that have fired ahead of the cold front over western MO, eastern OK, western AR, and far northeast TX. As this system moves east, this evening, storms are likely to coalesce into a squall line as they move through central and eastern AR. As they do, however, the atmosphere they are moving into is not quite as unstable. Part of this lessening in instability is due to timing - the storms will be moving into the area after peak heating when instability typically wanes. However, because they will build up a head of steam moving across AR, some of the storms will still have the potential to bring strong to severe straight line wind (50-60 mph) and small hail. And, as we typically warn in these scenarios, spin-ups within the squall line have the potential to drop brief tornadoes, though the threat of tornadic damage is not high.

Updated 8pm severe weather outlook from SPC showing a slight risk for the metro tonight

As for timing, models indicate storms could initially arrive in the metro anytime between 9pm and 1am and would last on the order of 2-4 hours. MWN is forecasting the storms to arrive during that window (or 11pm to midnight) and last for 3-4 hours projected from the current location and movement of the line in Arkansas. The line is generally following the lead of the high resolution model data from early this afternoon.

Hi-res computer model (HRRR) output showing "forecast radar" as of midnight CDT

In summary, Memphis metro residents should be prepared for the possibility of a narrow line of storms moving through the metro around 11pm to midnight bringing the possibility of strong straight-line wind and an isolated threat of hail or an isolated tornado. The line will be followed by general thunderstorm activity that will last into the wee hours Monday morning. All of this activity will be out of the area prior to the Monday morning rush hour. Only a few lingering showers are possible early Monday morning.

Follow us on Facebook and Twitter (links below) for the latest on the severe weather threat, as well as complete nowcasting coverage as the line moves through.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Central Plains tornado outbreak today, then storms march east towards the Mid-South

2012-04-14T14:03:00.001-05:00

Tornado Alley will be given a chance to live up to it's name today as the Storm Prediction Center has placed a very large area from Nebraska to Oklahoma under a High Risk for severe thunderstorms, predicting a "significant outbreak of strong to violent, long-track tornadoes" for the region (see first graphic below).

Several notable actions were taken in preparation for this event, including a very rare Day 3 Moderate Risk issued Thursday, a Day 2 High Risk issued yesterday (only once has this ever been done before), a Public Severe Weather Outlook from SPC (issued only when an outbreak is expected), and a 45% tornado risk area for parts of NE and KS (see second graphic below), meaning there is nearly a 1-in-2 chance of a tornado within 25 miles of any point within that area. The greatest tornado risk is this afternoon and evening, followed by the formation of a squall line over eastern KS and into OK this evening into the overnight hours.

A very large high risk area has been issued for the Plains in advance of an expected outbreak of violent tornadoes

Tornado risk for today - percent chance of a tornado within 25 miles of a point

On Sunday, a slow-moving squall line is expected to move east from the Plains as a Pacific cold front begins pushing east. Low pressure moving out of the Central Rockies that is providing the necessary low-level wind shear across the Plains for tornadoes today will move northeast into the western Great Lakes Sunday, so a significant tornado threat is not expected further south, thus wind and possibly some hail will be the primary threats during the day from the Mid-Mississippi Valley into northeast Texas (see Day 2 severe risk graphic below).

You'll notice that Sunday's slight risk area extends to just west of the metro. This is because the line of storms is expected to move east of the slight risk after midnight, when atmospheric conditions are least conducive for severe weather. I expect the line to weaken as it approaches the river after dark Sunday night and move through the metro before dawn Monday morning as a "general" line of thunderstorms. A remnant wind threat is still possible with the line, but the chance of severe weather is relatively low.

The bottom line: while tornadic storms are likely in the Plains today, the storms become more of a wind producer as they approach the Mid-South Sunday and will weaken further as they enter the metro area early Sunday. Until then, we'll experience warm, humid, and windy springtime conditions, followed by more typical springlike weather in the wake of the front and for the first half of next week.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Cool temps make a brief visit, then focus shifts to next rain chances

2012-04-10T20:40:00.000-05:00

With the passage of a cold front this morning, parts of the metro area saw a few quick-hitting showers to start the day. As the system moved to our south this afternoon, mostly sunny skies returned to the area, but the biggest impact of this front’s passage will be felt beginning tonight and continuing through Thursday as below-normal temperatures make an unusual stop in the Mid-South, at least considering the past few months!

With Canadian high pressure settling in from the north, the cooler temperatures will begin filtering in to the area under northeast winds this evening. Expect numbers in the mid 40s across most of the metro when you wake up Wednesday morning, with temperatures only rising into the mid 60s during the afternoon even under sunny skies.

However, as the high pressure area makes it closest approach to the region late Wednesday, and winds lighten, the setup will be in place for the coolest night in the Mid-South in about a month, as readings in the city of Memphis drop into the lower 40s by Thursday morning. Outlying areas of the metro will likely dip into the upper 30s. At this time, the threat for any frost looks to remain mostly north and east of the metro area with freezing conditions possible closer to the Tennessee River.

NWS forecast for Thursday morning, as high pressure makes closest approach to the Mid-South, in southern Indiana

As the high slides to the east of the Mid-South during the day Thursday, southerly wind flow will begin to return to the area, marking the start of a warming trend that will have temperatures back into the 80s by the weekend. Meanwhile, a series of storm systems developing over the Plains states will likely bring multiple rounds of severe weather to that area. Here in the Mid-South, though slight chances for rain and thunder may begin as early as Friday, it appears most of this activity will stay west of our area until at least Monday afternoon.

By that time, a slow moving cold front will finally begin to gain some momentum and head east toward the Mid-South, increasing our rain and thunderstorm chances for Monday night into Tuesday. It’s unclear at this point whether this system will bring any threat of severe weather to our area, but confidence is starting to increase in this period being the most active over the next week. More details will emerge as the week progresses on this system’s impacts to the Mid-South.

GFS model forecast for Tuesday morning, April 17th, depicting cold front just west of the region

Stay with MemphisWeather.Net for the very latest on the upcoming cool temperatures as well as our next significant rain chances. For the latest complete forecast, be sure to visit the MWN forecast page.

--Kevin Terry, MemphisWeather.Net

Recap of today's thunderstorms and a pleasant pattern ahead!

2012-04-05T19:48:00.001-05:00

We began the day in a Slight Risk area for the possibility of some severe weather thanks to a potent upper-level low pressure system that was traverse the metro this afternoon. During this time of year, with some heating ahead of one of these lows, it is possible to get large hail in any thunderstorms that form thanks to the cold air aloft and lower freezing levels. Instead of large hail, some areas saw buckets of small hail! Below are a couple of pictures from Summer Avenue near White Station around 10:10am where so much hail fell it covered the ground!

Small hail covered the ground on Summer and White Station around 10am. Photo courtesy @bengalkatlady (Twitter)

A couple of hours later, this was the scene as the hail was washed into a low lying area in the parking lot:

Remnants of the hail 30 minutes later. Photo courtesy @bengalkatlady (Twitter)

This storm developed very quickly over the city and moved slowly east. Below is a sequence of cross-sections of the storm put together by Weather Channel meteorologist Stu Ostro. Note the cell on the right size of the storm, which went from a small green dot in the top frame to a large red core held aloft by a developing updraft in the middle frame, and finally collapsed to the ground as pinks and reds (hail) in the bottom frame.

Time sequence cross-sections of the Memphis hail storm. Courtesy Stu Ostro.

From the south (backside) of these storms, mammatus clouds were present on the underside of the thunderstorm anvil clouds. The picture below was taken from Memphis International Airport looking north. Mammatus clouds are typically indicative of severe weather and extreme turbulence.

Mammatus clouds on the storm producing hail to the north of this location. Photo credit MWN.

After a brief respite, a line of storms moved into the metro from the west after the lunch hour. As the storms approached, they pushed out an outflow boundary, or gust front, that produced a photogenic shelf cloud. The pictures below show the shelf as it approached southeast Memphis and Collierville, respectively. Though no severe weather was associated with this storm, there were reports of near-severe size hail in north Mississippi in association with the line of storms.

Shelf cloud as it approaches Mendenhall south of Mt. Moriah. Photo courtesy @nas38117 (Twitter)

Shelf cloud from a distance, taken in Collierville by Michael Hardeman.

Precipitation rapidly diminished in the metro by 2pm as the upper-level low responsible for the day's weather moved nearly overhead and conditions stabilized behind the previous storms.

Looking ahead, a seasonal and very welcome pattern change is expected. Thanks to the rain today, for only the second time since March 11, temperatures remained below 70 degrees! As we head into the Easter weekend, high pressure will dominate, bringing very pleasant conditions with abundant sunshine, reduced humidity, and high temperatures in the upper 60s Friday and lower to mid 70s this weekend. A weak cold front will pass through early Sunday morning but only an increase in cloud cover is expected.

Another cold front that brings a shot of much cooler air arrives around Tuesday, further reducing temperatures to the 60s for the middle of next week. Overnight lows will be in the 40s Friday night and again for the middle of next week! Models are hinting at more rain chances late next week, but it's too early to say for sure now. In the meantime, enjoy some truly SPRINGLIKE conditions. A detailed look at the extended forecast can be found on the MWN Forecast page.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

March 2012 Climate Data and MWN Forecast Accuracy

2012-04-04T14:21:00.002-05:00

Following the 7th warmest meteorological winter (December-February) on record, March upped the ante! The month ended up as the warmest March in recorded history in Memphis and many other locations across the eastern U.S. The average temperature of 64.8 degrees was 10.8 degrees above normal, more than 2 degrees warmer than the second warmest March (2007). With no low temperatures at or below freezing, the growing season officially started on February 21, or a little over a month earlier than normal. Memphis missed the earliest "last freeze" by 9 days (February 12, 1878).

Memphis International Airport, Memphis, TN
As mentioned, the average temperature for the month of March was 64.8 degrees, 10.8 degrees above normal. The average high temperature was 75.2 degrees and the average low was 54.5. The coolest temperature of the month was 34 degrees on the 4th, while the highest temperature was 85 degrees reached on the 20th and 31st. There were only 3 days during the month on which the average daily temperature was below normal and 19 days on which the average daily temperature was 10 degrees or more above normal. There were 11 days in which the high reached 80 degrees or higher.

Precipitation for the month totaled 4.35", which was 0.81" below average. There were only 7 days with measurable rainfall but four of those had 0.50" or more. The maximum 24-hour amount was 1.44" on the 8th. The peak wind gust was 44 mph (from the south) on the 21st with an average wind speed for the month of 9.5 mph. Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions, Bartlett, TN
The average March temperature at Cirrus Weather Solutions in north Bartlett was 64.6 degrees with a maximum of 89.0 degrees on the 31st and a minimum of 31.5 degrees on the 4th. March precipitation totaled 3.85" in the automated gauge. A co-located manual gauge used for the CoCoRaHS program measured 4.07". The peak wind gust was 33 mph on the 2nd. Average relative humidity was 61%. Click here for a daily recap on MemphisWeather.net.

MWN Forecast Accuracy
For the month of March, the average temperature error in all MWN temperature forecasts was 2.59 degrees. 55% of the MWN temperature forecasts for the month were within 2 degrees of the actual temperature. MWN's forecasts extend out five periods (or 2.5 days). For dewpoint accuracy, the MWN forecast averaged 3.26 degrees of error and fell within 2 degrees of the actual dewpoint nearly 49% of the time. Historical accuracy statistics can be found here.

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

March 2012 was the warmest March in Memphis history

2012-04-01T20:50:00.000-05:00

The table below lists the Top 10 warmest March months at Memphis, TN since records began back in the 1880s. As the month ended, the average temperature for March 2012 was 64.8 degrees, which ranks as the warmest month of March in recorded history. Besides Memphis, other regional cities, including Jackson, TN, Tupelo, MS, and Jonesboro, AR, also ended with their warmest March on record!

A few other interesting climate facts for March 2012:

27 days had "above normal" average temperatures
18 days had average temperatures at least 10 degrees above normal
6 daily temperature records were either tied or broken
The previous warmest March was over 2 degrees cooler than 2012 (typically the warmest months are tenths of degrees apart - 2012 wasn't even close!)
As of March 31, our average temperature for 2012 (Jan-Mar) is also 1.3 degrees higher than the previous record warm year (1907) and 6.8 degrees above normal

TOP 10 WARMEST MARCH MONTHS

Rank	Avg Temp	Year	Departure
1	64.8	2012	+10.8
2	62.5	2007	+8.5
3	62.1	1907	+8.1
4	61.9	1910	+7.9
5	61.4	1921	+7.4
6	60.5	1938	+6.5
7	60.1	1945	+6.1
8	59.6	1908	+5.6
9	59.5	1878	+5.5
10	59.4	1946	+5.4

The spring outlook (below) indicates a likelihood of continued above normal temperatures for both the month of April and the 3-month period of April-May-June, according to NOAA/Climate Prediction Center.

April outlook from CPC calls for a 40% chance of above normal temperatures (27% chance of below normal)

April-May-June outlook from CPC calls for a ~50% chance of above normal temperatures (17% chance of below normal)

#mSpotter program allows Mid-South residents to submit storm reports via Twitter

2012-03-31T14:03:00.000-05:00

On Monday night, March 19, at the Agricenter in East Memphis, about 150 people turned out to learn how to be volunteer storm spotters for the National Weather Service. Following the two-hour training session, during which NWS personnel described what to look for in a severe storm and how to report it back to the NWS office, MemphisWeather.net meteorologist Erik Proseus invited those who had Twitter accounts to stay for a "bonus" training session on the brand-new #mSpotter storm reporting program. About 40 individuals listened as Erik described how social media can be used to further the mission of the NWS, that is to "protect life and property." While conventional methods of submitting storm reports to the NWS consist primarily of a phone call to the local office or submitting the report via a web form, #mSpotter allows those with Twitter accounts to send in their reports using their social media accounts.

The new program was designed to mirror a similar program (#tSpotter) in middle TN that has been highly-successful in the few months since it commenced under the oversight of Nashville attorney David Drobny, himself an avid weather enthusiast. The program works by having a "middle man" - in the case of #mSpotter that role is filled by MemphisWeather.net - monitor incoming storm reports from the Twitter-sphere around Memphis that are tagged with the #mSpotter hashtag and then pass them on to NWS-Memphis via a chat function utilized by all NWS offices across the country. #mSpotter encourages reports that are geo-tagged by the submitter's smartphone to allow for exact location information, as well as a picture of the event (i.e., hail, wind damage, flooding). This allows the "tweeted report" to contain exact information on the location and type of severe event that sometimes can be subjective or unclear (for instance an intersection that is not well-known).

#mSpotter reports will use primarily the same severe weather reporting criteria as traditional storm reporting: tornado/funnel clouds, 1/2" of larger hail, 50 mph wind or stronger, very heavy rain or flooding, weather-related structural damage, downed trees or power lines, and winter precipitation. In addition to the type of event, location, and time, as well as a geo-tag and picture if available, tweets should include the #mSpotter hashtag so that they are easily retrieved by MWN and can be relayed quickly to the NWS. The goal of #mSpotter is to provide the National Weather Service with reliable reports of severe weather more quickly than conventional means, thereby allowing meteorologists to more efficiently and quickly warn those ahead of the storm what severe weather threats the storm contains.

Anyone with a Twitter account in the 8-county Memphis metro area is welcome to submit storm reports via #mSpotter. We encourage you to read over the #mSpotter page on MemphisWeather.net prior to submitting any reports so that you are comfortable with how and what to send. Thanks for being a part of this community-based public service!

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

March arrived like a lion - will it go out like a camel?

2012-03-29T19:09:00.001-05:00

The early summer-like weather pattern has continued across the Mid-South much of this week, as temperatures remain well above normal. In fact, as previously blogged, the 80-degree weather that’s persisted much of this month will guarantee March ends as the warmest on record (hence the camel reference...), averaging about 10 degrees above normal for the month! In addition, we’re also watching a couple of weather systems over the next few days that will bring increased rain chances, as well as a subtle cool-down next week.

The first system will approach the region from the southwest Friday, bringing a risk for scattered showers and thunderstorms. The upper level disturbance responsible for the rain chances looks most likely to track just south of the metro area, meaning areas in Mississippi will have the best risk to get wet, though it will be possible anywhere. Organized severe weather is not expected, but a few of the storms could contain gusty winds as well as heavy rainfall and lightning. Temperatures Friday may be a touch cooler due to the increased clouds, probably holding just below 80 degrees.

WRF model for 1 PM Friday shows scattered t'storms, but mostly over MS

Rain chances decrease again Friday night and Saturday, as the upper level system passes to our east, and a weak front remains stalled just to our northwest. A rogue shower or thunderstorm is not out of the question, but most areas will remain dry, and temperatures Saturday will rebound to the lower 80s.

On Sunday, April may be welcomed in on a downright hot note as high pressure strengthens overhead. Temperatures are likely to respond and readings could very well reach into record territory. Mid 80s are a very good bet, and if maximum heating is reached, numbers may even approach 90 degrees in isolated areas! That’s not an April fool’s joke! Meanwhile, a new storm system will begin to organize over the Rocky Mountain States, poised to affect our area sometime between Monday and Tuesday.

GFS model temperatures for Sunday afternoon, showing widespread 80s, with upper 80s possible

Confidence decreases a good bit on the outcome of this next system, as computer models are in very different places on how and where this system tracks in relation to our area. One model “camp” takes the system well north of the Mid-South, with a trailing cold front passing through quickly Monday night. Meanwhile, another “camp” takes the core of the system right over the Mid-South, and is also much slower in clearing our region, taking until late Tuesday.

European model - with low pressure in Canada and cold front passing through the Mid-South Monday night

GFS model - with low pressure in northeast Arkansas and cold front still west of the region Tuesday afternoon

Both potential outcomes appear as if they will bring decent if not high chances for rain and thunderstorms to the Memphis metro, but the exact range of impacts is still to be determined until better agreement is reached. For now, MemphisWeather.Net is learning toward the former solution above, with a round of thunderstorms likely with a cold front’s passage Monday night, but this is subject to change. We will also be watching this system for the possibility of severe weather, as sufficient instability and wind dynamics may come into place near our area for the first time in several weeks. With the possibility of severe weather, now is a good time to check out StormWatch+, our newest addition to the MemphisWeather.net mobile app for iPhone and Android. StormWatch+ bring personalized severe weather alerts to the palm of your hand!

Following this system, it appears a slight cool-down may be in store for the area, with temperatures returning to the 70s, closer to normal levels. As of now, any more significant cool snap looks unlikely for the foreseeable future.

--Kevin Terry, MemphisWeather.Net

How to navigate the new MWN Facebook page

2012-03-27T19:45:00.000-05:00

www.facebook.com/memphisweather1

Well, Facebook has done it again! As you've no doubt seen, many individuals have begun using the new "Timeline" format that Facebook has developed. Now the Timeline has come to all Fan and Business pages. All fan pages will transition by this Friday, so you'll see many more in the days ahead (we held off as long as we could!). We hope to provide you with the information needed in this post to successfully navigate the new MWN Facebook fan page, including some of the pros and cons. We'll start with screen shots of the old and new versions of the page. To access our live Facebook page, in the new format, click the link above.

Figure A. MWN's "old" Facebook page

Figure B. MWN's "new" Facebook Timeline

The big changes are highlighted in red, while new items are in purple on the Timeline (Figure B). First of all, if you are looking for any of the information, or "landing tabs" as they were called, that were in the left column, you will now find those below the brand-new Cover Photo. These are now referred to as "apps." On our Timeline, you'll see "Photos" (which we cannot move), "Videos," "StormWatch+," and "Likes." Click on the drop down arrow/number next to the Likes button for additional apps that we may provide. Except for Photos, we can change the order of any of these or add new apps. The About section, which in the old format was very limited, has been expanded to show additional verbiage and appears next to the apps section below the cover photo.

Most importantly, posts by MWN to our Wall, which previously appeared in one main column down the body of the page, will start off in the left-hand column of the new Timeline format. At the top of the right-hand column will be things like what others are saying about MWN, our page's likes, etc. Then, below these items, our posts will take on a 2-column format, as in the screenshot below after scrolling down the page.

Figure C. After scrolling down MWN's new Facebook "Timeline"

We have the ability to "highlight" certain posts (which means they cross both columns) or even pin them to the top of the Timeline, as shown by the yellow bookmark icon (circled in purple) in Figure B above. You can navigate through our apps or go back in our timeline by month using the drop-down menu bar that appears at the top of the page after scrolling down past these features that are at the top of our new page (see purple circled area in Figure C).

While it will take some adjustment, there are a couple of new features that we think you will like (and I know we will). One is the ability to pin a post to the top of the Timeline. We can see using that for an important story, a bit of information that you need to know, or perhaps to let you know we are in nowcasting mode during severe weather. We have complete control over what appears at the top of the Timeline, which keeps you from having to dig back through multiple posts to find it.

Secondly, you'll see a "Message" button below the cover photo. This is a brand new feature to Facebook Fan Pages. Previously, in order to contact us, you had to write on our Wall and hope we saw it. Now, with "Message," you can use the Facebook Message system to wrote directly to us, just like e-mail. We can respond through Messages and the reply will appear in your normal Facebook Message stream, just like with personal Facebook messages you send. We encourage you to use that for questions or comments that may not be appropriate for a wide audience. If you want to write on our wall with a weather question that others may also be interested in, feel free! If you want to ask us a more direct one-on-one question, use Messages.

The last item to address is our severe weather nowcasting service. WE WILL CONTINUE TO NOWCAST DURING SEVERE WEATHER ON FACEBOOK. However... we expect that if you load our Facebook fan page and click refresh periodically, the new "Timeline" format may be harder to follow than the old (even though it should work well given it's name...). We honestly don't know exactly how it will work. If you simply follow your News Feed on Facebook, especially if you order your posts by "Most recent first," you should see no changes at all. The majority of you already do that. To arrange your news feed in this manner, go to Facebook.com, then at the top of the news items, click on "Sort" and select "Most recent." This is the best way to see our posts during severe weather in chronological order (see Figure D below).

Figure D. Setting up your News Feed

Finally, I'll make a plug for Twitter. If you are not on Twitter, consider it. Twitter is absolutely the BEST way to follow our severe weather nowcasting. It's always chronological, it's concise, links are provided in posts (tweets), and it's a rapid way of keeping up to date with what's going on. You can also mobile follow MWN, which means our tweets will go straight to your phone as text messages, which can be very handy if you are taking cover from a storm! You can turn on/off the mobile feature at will. You'll find us on Twitter as 'memphisweather1', or @memphisweather1.

The other option for following our Twitter stream is to click on the "Twitter feed" app under the cover photo, as shown below. You can bring this app up and it will auto-refresh as tweets are sent. It's also a good way to follow our nowcasting service if you don't wish to join Twitter.

Figure E. Click Twitter Feed to see our latest tweets from within Facebook.

Hopefully you'll get used to the new Timeline format quickly. While it was certainly not our idea and it will take some adjusting to, Facebook is free to use, so I guess we are at their mercy!

If you have any other Facebook suggestions for us, feel free to leave a comment below! We'll try and make this as painless as possible for you!

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.

Topography influences the weather - but in the Mid-South?

2012-03-18T20:30:00.002-05:00

It is fairly well known that topography, such as mountain ranges, has significant effect on weather patterns. For example, air flowing up the Front Range of the Rocky Mountains lifts and condenses and can bring feet of snow to places like Denver, CO. It's what is called an "orographic influence" on the weather. Closer to home, it's also widely-known that the Ozark Mountains, though not to the scale of the Rockies, also can have an effect on the local and downwind weather. But did you know that very small topographical features can also have an effect on the weather? I'm not talking about the bluffs protecting Memphis from tornadoes - that is a weather myth that never seems to die. However, there is a topographical feature in the Mid-South that had an effect on the weather just this afternoon!

Crowley's Ridge, an elevated area (like a series of narrow hills really) that runs north-south through eastern Arkansas, is about 300-500' higher than the surrounding Mississippi River Delta, or Embayment (see image to right). It's clearly visible on topographic maps, sticking up like a crooked spine in the middle of east AR. On days with warm, humid air in place and general instability (i.e., rising air) in the atmosphere (like many Mid-South summer days), sometimes all it takes is a little extra "oomph" to create showers and thunderstorms, absent a frontal system or upper-level impulse. Thanks to the early summerlike weather we have been experiencing, today was one such day!

Take a look at the radar image of east AR early this afternoon, shown below. The topography is underlaid on the radar data and Crowley's Ridge is indicated by the dotted orange line. What do you know? Showers formed along Crowley's Ridge! If you were to look at a loop of the radar data, you would see them form over the crest of the ridge, then move north-northeast in the direction of the winds at 10,000 feet, which is why it rained downwind of the ridge! That extra 400' or so of "lift" created by the ridge induced small showers to form! In fact, later this afternoon, cumulus clouds had formed once again right down the spine of the ridge (see second image below).

Showers formed over Crowley's Ridge, then moved NNE - the direction the wind was blowing at about 10,000'

Cumulus clouds, caused by warm temperatures, sufficient moisture, and a little "lift" from Crowley's Ridge, are visible in this satellite image over east AR.

Bottom line: it doesn't take a mountain to have an orographic influence on the weather, and it can happen in our own backyard!

Have you experienced weather phenomena that might have been influenced by the lay of the land below?

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For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.