Community Collaborative Rain, Hail & Snow Network

Baked Alaska

2013-06-19T21:32:00.001-06:00

While most of the lower 48 states were generally enjoying typical summer weather this week, Alaska residents suffered through a record-setting heat wave. It was just one month ago Tuesday that Anchorage had its last measurable snow.

The record heat was the result of a very strong ridge of high pressure in the upper atmosphere. The center of this "closed" high was located right over Alaska. Within the high air descends and warms, keeping skies clear allowing full sunshine. The high also moved very little during the last several days keeping any weather systems that might have brought relief at bay.

Upper level map (500 millibars, about 20,000 feet) showing the strong ridge over Alaska.

June 17 satellite image of Alaska showing cloud-free skies. Since Alaska is surrounded
by water, cloud-free days, especially over most of the state, are rare. Credit: NASA

Here are the records set as of Tuesday.


All-time records set on Monday, June 17

Records for Tuesday, June 18.

One of our Alaskan CoCoRaHS observers included comments about the heat in his observations this week. The station is AK-MS-11, Palmer 1.7 WNW, located about 40 miles northeast of Anchorage.

June 17
Hot, dry weather has produced the warmest high temperature I have recorded in nearly nine years of record keeping in Alaska. Yesterday I reached 81.4° F and cooled only to 59.6° F, my warmest overnight low in nearly nine years. Winds reached 20.6 m.p.h. early in the evening which provided some relief. Today may be even hotter as winds are presently light and skies are clear.

June 18
Sunny, hot weather drove my high temperature in Palmer to a phenomenal 83.9° F and increased winds overnight prevented it from dropping below 65.7° F for the overnight low. My maximum gust earlier this morning was 41.2 m.p.h. A high cloud layer has developed this morning giving partly cloudy skies and the wind is continuing.

Residents headed out to beaches and parks seeking releif from the heat and/or just taking advantage of the unusual summer weather. Stores sold out of fans. Those who didn't have fans had to endure, as air conditioning is not common in most homes in Alaska.While for most of us here in the lower 48 an 81°F day is pleasant in the summer, it's a record in Anchorage. The heat also brought out the mosquitoes in large numbers, with some residents calling it the worst they have ever seen.

Fortunately for Alaskan residents the weather will be moderating this week. High temperatures in Anchorage, for example, will be in the 60s to low 70s into the weekend.

ET - Moving Water Back into the Atmosphere

2013-06-18T23:18:00.001-06:00

If you Google "ET" or "E-T" the first several results returned are for the 1982 movie E.T. - The Extra-Terrestrial, about a boy who befriends an extra-terrestrial stranded on Earth. The "ET" that is the subject of this article isn't about visitors from outer space, but it is a concept that may be a little "alien" to many people.

ET stands for evapotranspiration, the process in which water vapor moves back into the atmosphere. Evapotranspiration is the sum of evaporation from ground surfaces and the transpiration of water to the atmosphere from plant leaves. ET is a function of temperature, wind speed, relative humidity, and solar radiation. Transpiration occurs when the roots of a plant draw moisture from the soil where it moves up through the plant to be released as water vapor from the leaves. On average more than half the precipitation that falls is returned to the atmosphere through ET. Studies show that transpiration by vegetation accounts for about 10 percent of the moisture in the atmosphere. An acre of corn can transpire about 3,000 to 4,000 gallons of water per day. The transpiration from agricultural crops is often significant enough contribute to the higher dew point temperatures that create muggy conditions during the summer and may enhance the formation of showers and thunderstorms. Conversely, the reduction in transpiration, such during drought, reduces the return of moisture to the atmosphere which in turn inhibits the development of showers and thunderstorms.

The E-T Gauge

CoCoRaHS observers measure what falls out of the atmosphere, precipitation. Beginning last year, however, a number of CoCoRaHS observers have been measuring evapotranspiration, or what is going back into the atmosphere, the "return" side of the water cycle. Evapotranspiration measurements actually began in mid-2011 with a few volunteers as a pilot project. Last spring the opportunity to make ET measurements was opened up to the observers at large. At present there are about 90 observers in 38 states making ET measurements across the country along with their rainfall (or in many cases, lack of rainfall) measurements. ET does not vary to the same extent as precipitation (it's more similar to temperature), so multiple measurements in the same general area are usually not needed, unlike precipitation. ET measurements are only made during the warm season, since freezing temperatures can damage the gauge.

The measurements are made using a special ET gauge developed for this purpose. The gauge consists of a water reservoir, with a cap consisting of a ceramic evaporator surface with a green fabric cover. In our case the fabric simulates evaporation over turf, so the gauge needs to be sited in a sunny, exposed area and preferably over grass. We are measuring "reference ET" which is defined as "the ET from an extensive surface of clipped grass… that is well-watered, and fully shades the ground." This reference ET is referred to as ETo . Another cover is available which simulatesevaporation over alfalfa (ET1). The cap is connected to a supply tube which extends the length of the reservoir. There is a sight tube on the exterior of the gauge which measures the water level in the gauge. The difference in water level from one observation to the next represents the evapotranspiration.

The measurement of both precipitation and evapotranspiration allows us to calculate an atmospheric water balance. Water balance charts are available on the CoCoRaHS web site (I also had one in my last blog post about New Mexico). This plots precipitation, ET, and the accumulated difference over time.

Water balance chart for ME-CM-3, located about 20 miles north of Portland, Maine.

Water balance chart for TX-ER-4, about 60 miles WSW of Fort Worth, Texas

Water balance chart for UT-ML-1, about 80 miles SSW of Salt Lake City

These charts provide a good sampling of the relationship between ET and precipitation and the water balance. When viewing ET charts, keep in mind that the charts do show multi-day ET values (total E-T over a period of more than a day), but the charts don't plot multi-day precipitation accumulations. Only daily reports are reflected on the charts.

The measuring of ET is relatively easy but there is a commitment of time and money. The ET gauges cost about $220, and there is a little more to setting up and maintaining them. However, the ET measurements are very useful and more importantly fill a big data need. Most estimates of ET are calculated, and the deployment of these gauges to CoCoRaHS observers represents the first organized effort to measure ET other than in automated, specialized networks.

For more information on evapotranspiration and the CoCoRaHS measurement program, visit the CoCoRaHS web site and select Evapotranspiration in the Resources menu of the left side of the page.

New Mexico in 2013 - Land of Dessication

2013-06-13T19:22:00.000-06:00

New Mexico's official "nickname" is the Land of Enchantment. It really is a beautiful state, rich in natural beauty and cultural heritage. One of my lasting memories of a vacation out west years ago was while driving through New Mexico during the late afternoon and entering a flat desert plain surrounding by towering mesas. The late afternoon sun combined with the colors of the landscape was an amazing sight.

Unfortunately, New Mexico has become ground zero of the drought that has been in progress over the western U.S. the past two years. A little over 82 percent of the state is in Extreme to Exceptional Drought according to the latest U.S. Drought Monitor. That's the highest percentage of any state currently affected. Conditions have significantly worsened over the last three months. At the start of the calendar year about 32 percent of the state was in Extreme to Exceptional Drought, and by March it was up to 50 percent.

CoCoRaHS observers have been documenting the drought impacts, and some of the descriptions sound like they could have come from the Dust Bowl. Here are two excerpts.

Santa Fe County
We are noticing that wild animals, birds and mammals, are increasingly desperate for water and therefore losing some of their instinctive fear of humans and other predators. The combination of severe drought and smoke from two wildfires nearby is making some mammals panic at times and come toward us rather than flee us when we are outside.

Rangeland in Lincoln County in April,
normally green at this time. Image credit: Twitter

Luna County
Because we've had so little moisture fall from the sky and we've had daily winds from 20 to 65/70 mph at least 80% of the population is suffering from "allergies" we didn't know we ever had! No one around here has a "lawn" of grass...instead we all measure just how deep the sand is now...the folks with the least amount of sand are considered lucky because they have less dusting/sand clean up to do on the inside of their homes. We've been told by a local farmer that he is now having to pay $20.00 for a bale of hay so he is going to have to sell all of his live stock next week - he can't afford to feed them any longer. And, we've heard that the local rancher spent over $100,000.00 in the last nine months trying to keep his cattle heavy enough to get them to market. We know that we haven't seen any of his cattle in our immediate area in the last 4 or 5 months...which means his heard head count is way down. Would you like us to start measuring the sand in our rain gauge rather than waiting for some moisture to land in it?

You can see the worsening of the drought in the water balance summary for a CoCoRaHS station in Bernalillo County in the north central part of the state. The station is NM-BR-56, Tijeras 3.7 N, located a few miles east of Albuquerque off of Interstate 40. This observer is not just measuring precipitation (or lack thereof), but also evapotranspiration (E-T). It is the only location in New Mexico with this measurement at the time. The average annual precipitation for this station is 18.54 inches. The annual total for NM-BR-56 in 2012 was 9.80 inches, just 53 percent of normal. So far in 2013 this station has only measured 1.85 inches of rain! The observer started E-T- measurements on May 15, and since that time has had more than 8 inches of water loss, and no precipitation. E-T rates have been running from 0.25 to 0.45 inches per day, and without rainfall you can see how quickly the deficit accumulates.

Water balance summary for NM-BR-56. Water balance is precipitation minus E-T.

The precipitation shortfall since the beginning of the calendar year is remarkable. All of the areas in red have 20 percent or less of normal precipitation.

Percent of normal precipitation for January 1-June 13, 2013.
The gray area indicates the data is missing for far western New Mexico on this map.
Map from the National Advanced Hydrologic Prediction Service

The large precipitation deficits have had obvious effects on the streamflow in New Mexico. The Pecos River basin is located on the east side of the state.

Hot, dry weather and tinder dry vegetation also translates into a high risk for wildfires. Several wildfires are already burning encompassing about 50,000 acres in total. A new fire was started by lightning in northern New Mexico this afternoon.

Satellite image of two of the wildfires in northern New Mexico.
Santa Fe is located just west of the Tres Lagunas fire.

Speaking of thunderstorms, there has been storms that have actually produced rain, but they have been few and far between. On June 5 thunderstorms covered Interstate 25 near La Bajada in Santa Fe County with 6 inches of hail. The southbound lanes of the Intersate were closed for over an hour until hghway crews could clear away the ice. As you might expect, the hail piling up on the highway caused several accidents.

New Mexico residents are looking forward to the onset of the summer monsoon season to provide some rainfall, but it certainly won't be enough to make much of a dent in the current drought. The outlook for the summer in the Southwest is for a higher than normal probability of warm and dry conditions persisting.

A CoCoRaHS History of Andrea

2013-06-10T18:56:00.000-06:00

Tropical Storm Andrea developed in the Gulf of Mexico last week and moved up along the east coast finally moving well out to sea Saturday. Andrea began losing tropical characteristics on Friday and by late afternoon Friday was extratropical. The low picked up speed and raced northeast along the coast Friday and Saturday. It finally turned out to sea and was absorbed by another low near Newfoundland Sunday.

Here is an animation of the CoCoRaHS precipitation map from Wednesday, June 5 through Sunday, June 9.

7-day precipitation accumulation ending Sunday, June 9. Not all precipitation
along the eastern seaboard during this period was due to Andrea, but
her footprint is certainly evident.

Andrea Poised to Soak Eastern Seaboard

2013-06-06T21:25:00.002-06:00

Infrared satellite image at 10:31 p.m. EDT. The center of Andrea is
approximately 30 miles west of Jacksonville, FL.
Image credit: College of DuPage

Tropical Storm Andrea, which became the first named tropical system of the season in the Atlantic Basin yesterday, is currently crossing northern Florida after dumping 2 to 4 inches of rain on the southern half of the state yesterday and last night. A tornado watch was in effect for much of Florida during the day. There were eight reports of tornadoes, most of which caused some damage.

The rain shield associated with Andrea has now spread north in to Georgia and South Carolina.

Radar image at 10:26 p.m. EDT. The red "L" indicates the center of Andrea.

The rain will continue spreading north as Andrea moves off the Florida coast and then takes a path hugging the east coast over the next several days.

Forecast track for Tropical Storm Andrea

Rainfall amounts from 2 to four inches, with locally higher amounts, are expected along the eastern seaboard from Georgia to Maine.

Rainfall forecast through 8:00 p.m. EDT Saturday, June 8.

CoCoRaHS observers - remember to submit Significant Weather Reports to report heavy rain, flooding, or other storm-related weather. These reports are immediately routed to your local National Weather Service Office. If you are going to be gone for part of the weekend and not able to make an observation be sure to review how to submit a multi-day accumulation if you aren't already familiar with this. There should be some interesting rainfall maps to look at the next three days.

Hurricane Season 2013 - What's Ahead

2013-06-01T05:00:00.000-06:00

Hurricane Andrew, 1992

June 1st marks the start of meteorological summer, and probably more significant for those on the east and Gulf coasts, it's the start of the 2013 hurricane season.The National Oceanic and Atmospheric Administration issued it's hurricane season outlook for 2013 about a week ago. The bottom line is that this is expected to be the fourth consecutive very active hurricane season in the Atlantic.

The outlook is based on current conditions in the Atlantic basin, expected atmospheric conditions over the course of the season, and model forecasts. The three key atmospheric factors that point to a very active hurricane season are:

A continuation of the atmospheric climate pattern, which includes a strong west African monsoon, that is responsible for the ongoing era of high activity for Atlantic hurricanes that began in 1995
Warmer-than-average water temperatures in the tropical Atlantic Ocean and Caribbean Sea
El Niño is not expected to develop and suppress hurricane formation.

NOAA estimates that there is a 70 percent probability that there will be

    13-20 Named Storms
    7-11 Hurricanes
    3-6 Major Hurricanes (Category 3 to Category 5) [link]

In other words, in all seasons with similar climate conditions to those expected this year, 70 percent of those seasons had activity that fell within the ranges above.

This compares to the official 1981-2010 seasonal averages of 12 named storms, 6 hurricanes, and 3 major hurricanes

How did the outlook verify in 2012? In May 2012 the NOAA outlook was for 9-15 named storms, 4-8 hurricanes, and 1-3 major hurricanes. The outlook was updated in August to 12-17 named storms, 5-8 hurricanes, and 2-3 major hurricanes. The actual count for 2012 was 19 named storms, 8 hurricanes, and 2 major hurricanes. The two major hurricanes were Michael, which did not make landfall, and Sandy, which did.

Tracks of the named tropical storms in the Atlantic basin in 2012

For a full-size, high resolution version of this map and track maps for previous years, visit the NHC Data Archive.

The 2010, 2011, and 2012 seasons each had 19 named storms in the Atlantic.

This Atlantic hurricane season outlook will be updated in early August, which coincides with the onset of the peak months of the hurricane season. The greatest frequency of tropical storms occurs in mid-September.

Number of tropical cyclones per 100 years

During the month of June tropical storm formation is favored in the Gulf of Mexico and the western Caribbean.

Here are the names of 2013 storms:

Andrea

Barry
Chanta
Dorian
Erin
Fernand
Gabrielle
Humberto
Ingrid
Jerry
Karen
Lorenzo
Melissa
Nestor
Olga
Pablo
Rebekah
Sebastien
Tanya
Van
Wendy

Hurricane preparedness week was May 23-June 1. For more information on tropical storms and how to prepare for them, visit the National Hurricane Center's Hurricane Preparedness web site. The site has video and audio presentations in both English and Spanish.

Sloshing Into June

2013-05-29T22:49:00.001-06:00

The last seven days have been a wet period from the Pacific Northwest to New England and for parts of Texas. CoCoRaHS observers have been busy measuring inches of rain in many areas. The first map below shows the accumulated precipitation for the past seven days. The second map shows the percent of normal precipitation.

Map compiled by the NWS Advanced Hydrologic Prediction Service

The greens to blue and violet colors depict normal to much above normal precipitation.
Map compiled by the NWS Advanced Hydrologic Prediction Service

The heavy rainfall, particularly in the Midwest, has been due to a frontal boundary that has extended from the western U.S. to the east coast. Since the weekend this boundary has been oscillating north and south as upper level waves have moved across the country. South of this boundary the air is warm and humid with dewpoints in the 60s. The warm humid air has fueled showers and thunderstorms along and north of the boundary.

Surface map for 7:00 a.m. CDT Tuesday, May 28, 2013

Over the next few days a much stronger upper level low will slowly move across the northern U.S.

500 millibar forecast map for 7:00 a.m. CDT Friday, May 31, 2013.

Heavy showers and thunderstorms are likely along this boundary once again, with from 2 to 4 inches of rain possible across the northern Plains and the Midwest.

Quantitative precipitation forecast for the 3-day period from 7:00 p.m. CDT May 29 to 7:00 p.m. CDT June 1, 2013.

This will prolong and worsen flooding along rivers in the Midwest. The Mississippi River from Burlington, Iowa south to St. Louis is mostly in moderate flooding at the present time, but with the expected rainfall the river is forecast to be in major flood during the first week of June at most river gauges along that reach.

This map shows the Maximum Forecast Flood Category through June 7, 2013. 0

More Unusual May Weather

2013-05-26T23:22:00.001-06:00

The road to Whiteface Mountain
on Saturday, May 25th.

This weekend saw another round of unusual weather at opposite sides of the country. In NewEngland, a remarkable spring storm dropped 24 to 34 inches of snow in upstate New York on Whiteface Mountain at an elevation of 4867 feet. A strong low pressure system moving through the northeast brought several days of heavy precipitation to northern New York and western Vermont. Precipitation totals for the past six days range from 5 to 9 inches, with the heavier amounts in Vermont. On Saturday the rain mixed with and changed to snow in northern New York and Vermont, with snow accumulating at elevations above 900 feet. Snowfall in Vermont ranged from 1.0 inch at Richford, VT to 18.0 inches at Jay Peak, VT (elevation 3862 feet). Some ski areas were reportedly open for the weekend thanks to the snow.

There was deluge amidst drought this weekend in Texas. Thunderstorms dropped more than a foot of rain on the San Antonio, TX metropolitan area. Some thunderstorms occurred during the afternoon Saturday, but heaviest rain fell in training nocturnal thunderstorms late Saturday night to early Sunday morning. Here is the CoCoRaHS map for Saturday, May 25 for Bexar County. San Antonio is located near the center.

The heavy rain caused flash flooding in the San Antonio area, with some streams approach record high flood levels. A new record flood stage was set on the San Antonio River Saturday morning.

River stage observations for the San Antonio River

The rain is sorely need in Texas, where lake and reservoir levels are very low from two years of drought. However, this was definitely too much too fast. Unfortunately the flash flooding caused three fatalities, caused a roof of an apartment complex to collapse, and inundated many roads.

Moore, Oklahoma Tornado

2013-05-20T20:33:00.000-06:00

The 12-month period from May 2012 through April 2013 tallied the fewest number of tornadoes for a 12-month period since 1954. There were only seven people killed in that 12 month period, the fewest since 1899. The unusually cool spring weather has been responsible for suppressing the severe weather this year. The switch seemed to be flipped about the middle of this month, however. On May 15 an EF-4 tornado struck Granbury, Texas north of Dallas and an EF-3 hit Cleburne in Johnson County. There have been tornadoes reported on every day since, with 30 tornado reports yesterday, and so far 15 today.

This afternoon one of those tornadoes swept through Moore, Oklahoma, a southern suburb of Oklahoma City. This was a massive, devastating tornado. I watched it on radar and on a live television feed out of Oklahoma City. It was scary to see even though I was hundreds of miles away. The tornado was at least a mile wide and was on the ground for about 20 miles (all of these numbers are preliminary until a survey can be completed). However, the most stunning realization that came to mind is that this is Moore's second encounter with a catastrophic tornado. On May 3, 1999 a massive tornado, rated F5 with winds in excess of 300 mph, struck Moore, killing 44 people, causing 581 injuries, and $1 billion in damages. Since May 1999 the residents of Moore have had other encounters with tornadoes, but none the magnitude of today's tornado.

Tracks of the May 3, 1999 and May 20, 2013 Moore tornadoes.
Compiled by the National Weather Service Oklahoma City.

Here is a video of today's tornado as it moved through Moore.

As I write this there are already 51 confirmed fatalities from today's tornado. Rescuers continue to search for survivors in one of three schools that were hit by the tornado. Whole neighborhoods are unrecognizable. The National Weather Service has preliminarily rated this tornado as an EF-4, but numbers don't convey the anguish of the families of those who lost their lives or the devastation to property that this community has experienced. There are a number of active CoCoRaHS observers in Moore and we hope they and their families are safe.

This tornado was well-warned. The tornado was on the ground for about 40 minutes, and a tornado warning was issued 16 minutes before the tornado developed. I was astounded to hear people being interviewed state that they didn't know a tornado was approaching. It drives home the fact that no matter how soon warnings are issued, all of us have some personal responsibility to make sure we are aware of what is going on. Do you have a weather radio? Every home and business should have one! There are smart phone apps that will alert you to severe weather wherever you are. The pendulum may be swinging back on this severe weather season. Make sure you are prepared.

April Recap - Cold, Snowy, Wet, and Dry

2013-05-16T23:02:00.002-06:00

The weather during April 2013 was, in so many words, all over the place. Record cold and snow dominated the north-central U.S. Record rainfall and colder than normal weather plagued the central U.S., delaying spring planting and causing major flooding. Dry weather in the southwestern U.S got drier and drought conditions worsened there. April was also drier than normal in the northeastern U.S.

Here are some April statistics from the National Climatic Data Center. Some of these are preliminary and may change as new data arrives and is tabulated.

North Dakota had its coldest April on record, 9.9°F below average.
South Dakota, Nebraska, Kansas, Oklahoma, Minnesota, and Wisconsin each had a top ten cold April.
It was the 7th coldest April on record for Alaska.
Approximately 3,430 record low temperatures and about 4,050 record cold daily high temperatures were tied or broken. In comparison, approximately 690 record warm daily high temperature records and 1,570 record warm daily low temperatures were tied or broken. (These numbers are preliminary and are expected to change as more data arrive.)
Duluth, MN had its snowiest month on record with 50.8 inches of snow, breaking the old record of 50.1 set in November1991. The previous record for the snowiest April was 30.6 inches in 1950.
The April snow cover extent in the U.S. was the 5th largest on record.
The April average precipitation for the contiguous U.S. tied with 1953 as the 19th wettest April on record.
Iowa and Michigan both had their wettest April on record.
Tennessee, Illinois, Indiana, and Wisconsin each had one of the ten wettest Aprils on record.
While drought conditions improved in the central U.S., they worsened in the southwestern U.S. California experienced its driest January-April on record with only 27% of average precipitation. Snowpack in the Sierra Nevada was only 18% of normal.

Here is how the states ranked for temperature and precipitation.

You can read more about the April weather on the National Climatic Data Center's State of the Climate National Overview page, including narratives of regional highlights provided by the Regional Climate Centers.

Lumbering Low Lingers

2013-05-08T22:57:00.000-06:00

The major upper level trough that brought snow to the Rockies, Midwest and as far south as Arkansas the first two days of the month is still producing rainfall in the eastern U.S. a week later.

The trough developed a closed circulation on May 3 and the closed low has been slowly, very slowly, making its way east through the southern half of the country.

Animation of the 7:00 a.m. CDT 500 millibar map for May 2-7, 2013

This morning the upper low was centered over northern Virginia and was responsible for more than two inches of rain in the mid-Atlantic region in the past 24 hours.

The path of this system can be seen in both the precipitation and temperature patterns for the past 7 days. Precipitation from the Plains through the southeastern U.S. has been much above above normal as you might expect. The persistent cloudy, rainy, and cool weather has significantly delayed spring planting.

Total 7-day precipitation ending the morning of May 8, 2013.
Map from the NWS Advanced Hydrologic Prediction Service.

The low's progress across the country can also be discerned from the temperature departures over the last week. Temperatures were much below normal along the storm's path. The ridge of high pressure over the northeastern U.S. kept temperatures much above normal from the Great Lakes through New England. Temperatures were also warmer than average along the west coast and in the Pacific Northwest where a high pressure ridge was also situated.

The closed low will continue moving northeast the next two days, and will finally dissipate as it moves off of the New England coast on Friday.

Heavy Snow, Heavy Rain, and Wildfire

2013-05-02T22:45:00.002-06:00

It was another eventful weather day across the country, and not in the way you would normally picture the second day of May. The storm that brought snow to an area from the Rockies to northwestern Wisconsin continued to crawl eastward today, leaving a lot of records in its wake. A trough along the central Gulf brought 5 to more than 10 inches of rain to southwestern Alabama and southeastern Mississippi. Dry, warm, and windy weather prompted red flag warnings for southern California and other portions of the southwest U.S.

As of this morning a surprising 10 to 15 inches of snow was on the ground from southeastern Minnesota through northwestern Wisconsin, and accumulating snow continued in Wisconsin during the day.

Map prepared by the NWS Duluth office

As you might imagine, May snowfall records toppled with this storm. The NWS Cooperative Observer in Dodge Center MN (Dodge County) reported 15.4 inches of snow in the 24-hour period ending at 7:00 a.m. CDT this morning. If verified, this would be a new daily snowfall state record for May in Minnesota breaking the old record of 12 inches set on three previous dates, the most recent on May 3, 1954 near Leonard, MN. Daily snowfall records were set at many locations in the storm-affected area in Iowa, Minnesota, and Wisconsin.

You can read more about the record snow in Minnesota and Wisconsin at the following NWS office web pages:

National Weather Service, Duluth MN
National Weather Service, LaCrosse, WI

In Omaha, NE the snow on May 1 and May 2 set daily records on both dates. The combined total of 3.1 inches for May 1-2, 2013, is a record snowfall event in May as well as a record highest monthly snowfall total ever recorded in May. In Lincoln, NE May 1 snowfall was 2.4 inches on May 1 and 0.2 for today (May 2), both daily records. Kansas City, MO set new daily snowfall records on both May 1 and May 2. The combined total of 3.1 inches for May 1-2, 2013, is a record snowfall event in May as well as a record highest monthly snowfall total ever recorded in May.

This storm was clearly evident in the temperature pattern across the U.S. today, reflecting the strong upper level trough.

500 millibar (about 20,000 ft) upper level map for 7:00 p.m. CDT May 2

Surface temperatures at 7:00 p/m/ CDT May 2

The upper level ridge over the western U.S. was providing sunny and very dry weather. In California these conditions along with the Santa Anna winds combined to produce critical fire wildfire conditions in southern California, southern Nevada, and central Arizona. Red flag warnings were in effect for most of these areas today.

Fire weather outlook for May 2 issued by the NWS Storm Prediction Center

A wildfire in the Los Angeles area that initially was confined to about 10 acres this afternoon grew rapidly to 6,500 acres by late afternoon and as of this post is about 8,000 acres. A second wildfire was burning east of Los Angeles in Riverside County.

A slow-moving low pressure system along the central Gulf coast was brought up to a foot of rain to extreme southwest Alabama near Mobile and southeastern Louisiana.

CoCoRaHS rainfall map for May 2

Thunderstorms continued today, and more heavy rain is possible overnight.

A Crazy Start to May

2013-05-01T22:43:00.000-06:00

Here it is, the last month of spring, when most are anxiously await the unofficial start of summer in four weeks. However, winter is hanging on by its fingernails in the central and western U.S. and the cool spring continues over much of the country.

Snow today in Fort Collins, CO.
Photo by Zach Schwalbe

Winter weather in May is not unusual in the Rockies, but it is in the central Plains and Midwest. Cold air remains entrenched over the northern U.S. The lowest temperature in the nation this morning was 9°F at Denton Montana. Even late this afternoon, temperatures were in the 30s from Wyoming and Colorado, across Nebraska and northeast through Minnesota. Heavy, wet snow began last night and continued falling in the Front Range much of the day, and this afternoon began spreading across Nebraska. By late afternoon several inches of snow were on the ground in Grand Island in central Nebraska. By this evening snow was falling from eastern Nebraska through northwestern Iowa northeast to Minneapolis. Two days ago temperatures were in the mid 80s in the southeastern half of Nebraska and in the low 80s as far north as Minneapolis!

Surface map at 4:00 p.m. CDT May 1

South and east of the low pressure center and ahead of the very strong cold front, severe storms developed in Oklahoma and Texas with a number of reports of quarter to golf ball size hail. Note the huge temperature gradient across new Mexico and the panhandle of Texas. At the time of this map (6:00 p.m. CDT) temperatures ranged from 39°F at Clayton, NM in the northeast corner of the state to 91°F at Carlsbad in the southeast corner of New Mexico. Winds behind the cold front were north at 20-30 mph gusting to 45 mph.

Surface temperatures at 6:00 p.m. CDT May 1

The high temperature in the nation today was 101°F at Dryden, Texas (just inside the 95 degree contour on the map). Most of the southeastern half of the country enjoyed warm spring temperatures this first day of May. Much of this same area enjoyed sunny weather as well, with the exception of portions of the Gulf coast and Florida where showers and thunderstorms occurred.

The weather will be turning cooler and wetter in the Midwest and east over the next several days, but that's another story.

Soaking Rain in Tennessee and Texas

2013-04-28T22:49:00.000-06:00

Surface map at 1:00 a.m. CDT April 28

Heavy thunderstorms brought inches of rain to several counties in southeast Texas and a large portion of northern Tennessee and adjacent portions of Kentucky, and both were the result of the same general weather system. The clusters of thunderstorms in Texas developed ahead of a front draped across southeast Texas. The thunderstorms in Tennessee were associated with a low pressure wave
moving northeast along that front. Precipitation from these storms topped five inches in both states, with heavier amounts more widespread in Tennessee.

The clusters of thunderstorm developed over Texas during the afternoon. Rainfall amounts exceed 6 inches on the northeast side of Fort Bend County. CoCoRaHS observers in Sugar Land reported 6.55 and 6.12 inches of rain. Numerous rainfall reports of 4 to 5 inches was also observed in Lavaca, Harris, and Goliad counties


Southeast Texas rainfall for the morning of April 28

Here is the regional radar for that area from late afternoon on Saturday/

Regional radar at 5:57 p.m. CDT April 27, 2013

Thunderstorms rolled across Tennessee both Friday and Saturday, and two-day totals exceed 7.50 inches in Montgomery County, with 7.52 inches reported by the CoCoRaHS observer at Clarksville 10.2 WSW. The heaviest rain, generally in excess of 5 inches, fell during the day Saturday, but rain continued through Saturday night.

Flood advisories remained in effect Sunday night for a number of rivers in the Nashville area. Flood warnings are in effect for rivers in Montgomery County tonight, with area rivers expected to fall during the day on Monday.

A Tough Spring for Farmers

2013-04-24T14:09:00.002-06:00

Warm weather in March last year helped farmers get an early start to planting, but expanding drought impacted crops throughout the summer. This year, unusual cold and wet weather is delaying planting and likely damaging some crops. It's already a tough year for farmers (and gardeners, too) and we're just getting started.

As of Monday, April 21 only 4 percent of the corn crop was planted, with most of it in Texas and North Carolina. That's compared to a five-year average of 16 percent - last year it was 26 percent. In the Corn Belt states of Iowa, Illinois, and Indiana, little corn has been planted (1 percent in Illinois and Indiana, nothing in Iowa), compared to about 50 percent planted last year. With the tremendous amount of rain in the past week soils are saturated and it will be at least another week to 10 days before fields dry out enough to work, providing there isn't any more heavy rain. For those areas near flooding rivers it will be even longer.

The cold weather is taking its toll as well. It has been unseasonable cold all week, and today was another record cold morning across the central U.S. Amarillo, Texas dropped to 20°F this morning, shattering the old record of 32°F set in 1913 and again in 1958. Temperatures were in the upper teens to mid 20s across most of the Plains this morning. This is the major growing area for hard red winter wheat, and there was likely some damage to the crop especially in the southernmost states of Kansas, Oklahoma, and Texas where crop development is further along. After coping with drought last year and over the winter, wheat farmers may have taken another hit from the cold weather.


Minimum temperatures as of 7:00 a.m. CDT April 24

Of course, the drought still persists through much of that same area, and even with some improvement in the next few months there will still be lingering effects from the long term dryness.

Water, Water, Everywhere...

2013-04-22T11:19:00.002-06:00

It's hard to believe that only five months ago the flow on the Mississippi River was so low that authorities were planning to shut down the river to barge traffic. This morning major flooding is occurring along the Mississippi River and many other rivers in the Midwest from the torrential rain over a three-day period last week.

U.S. river observations as of April 22, 2013
From the NWS Advanced Hydrologic Prediction Service

The slow-moving weather system that moved across the country last week left more than 8.0 inches of rain in its wake. This rain fell on ground already saturated from precipitation earlier in the month, and much of the rain ran off into rivers and streams.

7-day precipitation accumulation for the period ending April 21
From the Midwestern Regional Climate Center

The highest precipitation totals reported by CoCoRaHS observers in each state for the period April 17-19 include

8.20    IA-MA-4 Pella 0.7 SE, Marion County
8.10      MI-AN-4     Fennville 0.8 W, Allegan County
7.43      IL-DP-27     Naperville 2.1 SE, DuPage County
7.20      IN-BN-2      New Ross 2.0 E, Boone County
6.15      MO-RN-2    Clifton Hill 1.2 SE, Randolph County

Hydrograph for the Illinois River at Peoria.
From the NWS Advanced Hydrologic Prediction Service

Flood stages approached or exceeded record levels at a number of locations. The Rock River at Moline, IL crested at 16.53 feet, breaking the record of 16.38 feet set on March 6, 2008. The Illinois River at Peoria reached a record level of 29.18 feet this morning breaking the old record of 28.8 feet set in May 1943, and is expected to crest at or above 30 ft. on April 23. The Grand River at Comstock Park in Michigan reached a record level of 17.8 feet on Sunday, April 21, breaking the old record of 17.75 feet set in March 1948.

In addition to flooding on rivers and streams there was widespread urban flooding and overland flooding of fields and rural roads in the affected states.

Here are some links to some photos of the flooding in the Midwest. You may also find other photos at individual NWS office web sites.

Grand River, Michigan flooding

Flooding on Illinois River near Marseilles, IL

Illinois River Flooding, Chillicothe, IL

The U.S. Geological Survey map of streamflow across the country is a picture of "feast or famine", Streamsflows are at very high levels in the Midwest, while they remain much below normal in much of the west and southwest, a mark of the persistent drought.

An Elusive Spring

2013-04-21T12:32:00.000-06:00

The far western and southeastern third of the U.S. have enjoyed a warmer than average April so far, but warm spring weather has been a hit or miss (mostly miss) proposition for the central U.S.

Temperatures from the Dakotas through central Texas have been below normal this month. Temperatures have been 10 degrees below normal across the Dakotas and Minnesota, with with departures of more than 15 degrees below normal in North Dakota. The cold is one thing, but these areas have also received 5 to 6 times normal April snowfall.

Deep snow cover over Canada has maintained the supply of cold air this spring and there is still 30 cm (12 inches) or more on the ground across the Prairie provinces. A persistent upper level trough pattern over over the central U.S. has deflected the storm track farther south this spring and allowed the cold air to spill farther south than normal.

Snow depth over Canada and the northern U.S. as of April 20.

In the past two days more than 600 record lows and 560 record low maximum temperatures have been recorded from the Dakotas to the southern tip of Texas.

Record low temperature records set or tied on April 19, 2013.
Maps from the National Climatic Data Center

Record low temperature records set or tied on April 20, 2013.
Maps from the National Climatic Data Center

Yesterday morning lows were in the single digits in the Dakotas and Minnesota and in the 30s as far south as the Big Bend area of Texas.

Minimum temperatures for the morning of April 20, 2013

Is there light at the end of the tunnel? There's a light, but it might be another freight train, at least in the short term. An upper level system is moving into the Pacific Northwest today and will drop into the central Rockies by Tuesday. The surface low will organize in the Central Plains and bring another round of snow to an area from Wyoming and Colorado to Minnesota. Another surge of cold air will follow this system.

Probability for 4 or more inches of snow between 7:00 a.m. CDT Monday, April 22 and 7:00 a.m. Tuesday, April 22

Forecast high temperatures on Friday, April 26.

However, a warmup is in the cards by next weekend, and there are indications that spring may finally take hold as we wrap up the month of April.

Wet, White, and Wild Weather

2013-04-18T09:07:00.002-06:00

Surface map at 7:00 CDT April 18

This has been an interesting week for spring weather from the Rockies through the Midwest. In the last 24 hours there have been flooding rains, heavy snow, severe thunderstorms, and tornadoes, all related to the same weather system

Much of Colorado got more snow in the past 24 hours, with as much as 15 inches in south-central Colorado near Pueblo. Snow also accumulated 2 to 3 inches in western South Dakota and 2 to 4 inches in northern Minnesota. Snow also occurred in Nebraska and northwestern Kansas.

24 hour snowfall ending the morning of April 18

On the warm side of this system. severe weather was reported from Oklahoma to Indiana. Two tornadoes touched down in Oklahoma, baseball size hail pummeled locations in Missouri, and thunderstorm winds gusted to 90 mph in western Illinois.

The heavy rain produced by this weather system has caused flooding from the southeastern half of Iowa through northern Missouri and across the northern third of Illinois.

24 hour precipitation ending at 7:00 a.m. CDT April 18

Many rivers and streams are in flood, and record flooding is possible for some rivers in northern Illinois. As of 10:00 a.m. CDT this morning 170 CoCoRaHS observers reported more than 4 inches of rain, and of those, 54 reported more than 5 inches of rain. Below are the highest rain amounts in the last 24 hours from CoCoRaHS observers.

CoCoRaHS reports for April 18, 2013

It's not over, either. More heavy rain is expected today ahead of the cold front as it sweeps through the Midwest, and severe weather is likely from Indiana eastward. Winter weather advisories are in effect from northern Kansas to Lake Superior and a winter storm warning is in effect for portions of Minnesota into northwestern Wisconsin and the Michigan U.P.

24-hour expected precipitation from 7am CDT 4/18 to 7am CDT 4/19

Watches, warnings, and advisories in effect aas of 10:00 a.m. April 18

The NeverEnding Winter

2013-04-16T11:12:00.000-06:00

Snow depth the morning of April 16, 2013

Springtime warmth has made an appearance in parts of the eastern half of the nation, and April showers are rapidly turning the landscape from brown to green. However, winter has kept an icy grip on an area from the Rockies through the Northern Plains to the upper Midwest. Late last week snow and ice fell from Nebraska to Wisconsin, and over the last few days more than a foot of snow has piled up in parts of Colorado and the Dakotas.

48 hour snowfall accumulation ending
the morning of April 16, 2013

The snow in the Dakotas resulted from a storm system that moved from Kansas and Nebraska northeast through Minnesota over the weekend. Ten to 16 inches of snow was reported from northern South Dakota through central North Dakota, with 3 to 6 inches of snow across northern Minnesota. In Bismarck, ND numerous records were shattered by this storm. On Sunday, April 14th Bismarck has 17.3 inches of snow, breaking the old record for that date of 5.0 inches set in 1986. It also set a new daily record for the month of April, breaking the old record of 15.2 inches on April 5, 1997. This was also the record snowfall for any calendar day of the year! The previous record was 15.5 inches on March 6, 1966. The storm total snowfall of 21.5 inches as of the morning of April 15 is a new record for April, topping the old record of 18.7 inches in April 1984. A number of locations in North Dakota reported 20 or more inches of snow from this storm, with 22 inches reported by the CoCoRaHS observer in Center, ND (ND-OL-2)

The snow in Colorado yesterday was produced by another low moving across the Great Basin. This setup is ideal for snow along the Front Range. Easterly flow resulting from the low to the west and strong high pressure to the northeast forces the air to rise as it encounters the Rockies, condensing the moisture and producing precipitation.

Surface map for 2:00 a.m. EDT April 15, 2013

These storms often produce lots and lots of snow, and this system was no exception. A foot of snow and more fell across the Fort Collins, Co area, home to CoCoRaHS headquarters.

CoCoRaHS snowfall in Fort Collins, CO April 16

Snow in the Denver area ranged from around 4 inches east of the city to 12 to 24 inches in the higher terrain west of Denver, with 24.5 inches of snow reported by a CoCoRaHS observer in Golden (CO-JF-267).

CoCoRaHS snowfall for the Denver Metro area, April 16

And it isn't over yet. The system that brought the snow to Colorado will be lifting out to the northeast, and winter storm warnings are in effect for portions of Wyoming, Nebraska, and South Dakota. Winter weather advisories are in effect for parts of Montana, Wyoming, Colorado, Utah, and Nevada.

Watches, warnings, and advisories effective 10:00 a.m. MDT April 16

If there is a silver lining to all of this it is that the moisture from these snows will certainly help provide some relief from the drought conditions that exist across the central and western U.S.
piled up in parts of Colorado and the Dakotas.

First Tornado Hook Echo Observed 60 Years Ago Today

2013-04-09T09:46:00.000-06:00

Note: The day after this story was posted I was contacted by Don Stagg's wife (who is a CoCoRaHS observer) with some additional information on the events that occurred that day. I have revised the story to reflect this information.

Today thunderstorms and tornadoes are routinely tracked using weather radar, and in fact anyone with a computer or smart phone can pull up the latest radar images for their area. As you might surmise, this wasn't always the case. After World War II surplus radars were being used to study thunderstorms and precipitation. The Illinois State Water Survey, a state agency on the University of Illinois campus, was in the beginning years of a weather research program at the time, a program that continues today. It was during a project conducted by the Water Survey that the now classic "hook echo" radar signature radar was first discovered and photographed in detail. As with many scientific discoveries, it was a serendipitous event.

Meteorology building at Willard Airport and the radar used
to detect the hook echo.

In the late afternoon and early evening hours of April 9, 1953 scattered thunderstorms were moving eastward across central Illinois. At the University of Illinois Willard Airport located a few miles south of Champaign, the Illinois State Water Survey was operating a radar collecting rainfall data for a project to determine the utility of radar for the measurement of precipitation amounts. The radar was a modified 3-centimeter wavelength radar that had been used as an airborne surveillance system installed aboard U.S. Naval aircraft in World War II. A rain gauge network had been established in east-central Illinois to provide ground truth for the radar-indicated amounts. That day, radar engineer Donald Staggs and an assistant were working at the radar. The radar was only operated as needed for this project, and the normal procedure was to turn off the radar after precipitation had passed through the rain gauge network. However, on that afternoon Staggs noticed the peculiar radar echo with the thunderstorm and thought “I wonder if that might be a tornado.” Ten minutes later he received a phone call from a woman who lived just north of Champaign. She wanted to know if he was seeing "the twister that just destroyed my barn" on radar. At that point he knew that the hook echo might just indicate a tornado and kept tracking it and photographing the radar display as the storm moved into Indiana. This distinct tornado echo, which was observed near the southwest edge of the associated thunderstorm, contained the tornado funnel.

The first hook echo identified and photographed on radar.

Although Staggs recognized the unusual nature of the radar echo and the possibility of a tornado, positive identification was not made at the time of the radar tracking. Only when the radar film was developed the next day did the scientists realize that the distinctive hook echo was the signature of the tornado reported the afternoon before. Field surveys confirmed the tornado, whichwas eventaully rated an F3.

The tornado moved east and dissipated just over the Indiana state line. It had a path of about 54 miles, and destroyed eight homes and damaged 72 others. There was one fatality in Vermilion County, Illinois from the storm.

A view of the tornado on April 9, 1953 taken from near Royal, Illinois.
Tornado photograph taken by Ernie Kienietz, provided by Scott C. Truett

The original report on this historic event is available online, and contains a description of the weather conditions that day, information on the weather radar, and the results of the field survey of the tornado damage, including photographs. It's a fascinating piece of weather history. You can read it at the following link.

Study of an Illinois Tornado Using Radar, Synoptic Weather and Field Survey Data, Illinois State Water Survey Report of Investigation 22, Urbana, IL by F.A. Huff, H.W. Hiser, and S.G. Bigler. 1954

In the report's conclusion, the authors of the report speculated that with more collection of tornado radar data, "...it may be possible to establish radar storm warning systems in tornado areas to reduce loss of lives, and to some extent property damage." This discovery did, in fact, launch a national research program aimed at tornado detection by radar. In 1962 the National Severe Storms Laboratory was formed out of the National Severe Storms Project, conducting research on the detection of storms with radar. Today, there are 164 weather radar sites across the U.S. that scan the skies 24/7.

Every Home Should Have a Weather Radio

2013-04-03T09:18:00.000-06:00

Trained meteorologists can forecast the development of severe weather. The latest weather radar technology can detect the signatures and features that signal the formation of severe storms and tornadoes. Warnings are issued as soon as the threat is evident.

How do you and your family receive the warnings that are issued? If there is a tornado warning your community may use sirens to alert those who are outdoors (sirens are NOT meant to warn people indoors). You may hear it if you are near a radio or television. If you are inside with the windows closed and music playing, for example, how will you know? If it is in the middle of the night and you are sound asleep, how will you know about the warning?

The answer is a weather alert radio. Just like every home should have smoke detector, every home and business should have a weather alert radio.

In the aftermath of storms we often see people interviewed who say "It struck without warning". What that statement usually means is "I wasn't aware of a warning", because in most cases a warning was not only issued, but issued with enough time to take shelter. Everything from the forecast to the warning can be perfect, but if people aren't receiving the information then that information can't help them.

There are over 1,000 weather radio transmitters in all 50 states. Most of the time the programming is routine forecasts and information. When the weather turns severe, however, the weather radio is your direct line to the latest storm information. About ten years ago the NWS Weather Radio network became part of the Emergency Alert System (EAS) managed by the Federal Communications System. With this capability the public can be alerted to information about natural disasters (such as earthquakes), civil emergencies, toxic and chemical spills, and child abduction Amber alerts in addition to the weather watches, warnings, and advisories.

Weather radios come in portable models that you can take with you to outdoor events or other activities like hiking or camping. Some have crank and/or solar recharging capabilities. Desk models run on AC power with battery backup. The prices of radios range from $25 to $135, with most desk models in the $40 to $75 range. One feature you should seriously consider is a radio with SAME (Specific Area Message Encoding) capability. This allows users to receive messages only for their designated county or counties of interest rather than the entire broadcast area. This is especially nice at night, as your radio alert will not be activated for areas you have not selected. On the basic radios without SAME any alert issued for any area covered by a specific transmitter will be triggered on the radio.

There are only seven VHF frequencies used for NOAA Weather Radio transmissions.

NOAA Weather Radio frequencies in the U.S.

The NWS has a listing of all U.S. stations and overage areas.

NOAA Weather Radio coverage map for Oklahoma

This site also includes a county by county listing of weather radio stations in each state and their current status.

NOAA Weather Radio station status for Illinois counties

NOAA also has a web page with consumer information, including a list of resellers of weather radios.

Weather radio receivers will also work in Canada. Environment Canada, the government agency responsible for producing official forecasts, operates a network of "Weatheradio" transmitters which generally operate on the same frequencies as the U.S. NOAA Weather Radio network. More information on weather radio in Canada can be found here.

It's worth repeating - every home should have a weather alert radio.

2013 Thunderstorm Season - "Impact Based" Tornado Warnings Experiment

2013-04-01T22:36:00.001-06:00

The NWS Central Region states and offices participating

April 1st marks the start of the thunderstorm season in the central U.S. This year 38 National Weather Service offices in 14 states that comprise the NWS Central Region will be issuing tornado warnings using enhanced messaging to emphasize the particular nature and danger of a storm. These "impact based warnings" (IBW) are an experiment to better communicate the expected impact and damage from a tornado in order to provide additional information to the media and emergency managers and better motivate people to take appropriate action.

This experiment was developed after an assessment of the May 2011 tornado that devastated Joplin, Missouri killing 158 people. There were three key findings from this assessment:

The majority of people identified local outdoor warning systems as their first source of warning.
The majority of people sought confirmation from additional sources before seeking shelter.
Credible, extraordinary risk signals prompt people to take protective actions.

A number of "tornado tags" will be utilized for tornado. Two tags will indicate whether the tornado was detected by radar or observed by spotters or law enforcement. Damage threat tags will be used to convey the level of damage expected from a particular storm. Warnings will include the particular hazard (tornado, hail), the source of the information (spotter confirmation, on-going damage), and the impact and type of damage expected.

The IBW tags allow the forecasters to distinguish between a low-impact event (for example a weak, short-lived tornado) and a high impact event (a large, long-lived tornado) Large, damaging tornadoes are relatively infrequent, so most of us will never hear a warning for a tornado causing considerable or significant damage.

In 2012 NWS offices in Kansas and Missouri utilized the impact based warnings. Below is a warning issued last year using the enhanced wording. The changes from a "standard" warning are highlighted in red.

Tornado warning issued on April 14, 2012 for central Kansas.

At the conclusion of this storm season the IBW experiment will be independently evaluated to determine its effectiveness.

Will changes in wording actually make a difference? This is an experiment to find out. Public response to warnings is a complicated issue and something that the NWS and emergency officials have wrestled with for years. How the information is communicated (sirens, the broadcast media, the Internet) and the content of the message that is being communicated are two sides of the same coin.

You can read more about the Impact Based Warnings experimental product at this NWS Central Region page.

More background on what was learned from the 2011 Joplin tornado can be found at NWS Central Region Service Assessment Joplin, Missouri, Tornado–May 22, 2011

New Look For Storm Prediction Center Web Site

2013-03-28T07:17:00.001-06:00

The NWS Storm Prediction Center (SPC) launched it's new home page today, sporting a sharp new look and quick, easy access to SPC products. SPC is responsible for forecasts and watches for severe thunderstorms and tornadoes over the contiguous United States. The SPC also monitors heavy rain, heavy snow, and fire weather events across the U.S. and issues specific products for those hazards.

The Overview map with the tabs across the top remains the centerpiece of the page but is off on the left side. On the right side a window contains thumbnails and links to all SPC graphical outlook products. Tabs on this window can be used to view the convective outlooks, current watches, mesoscale discussions, and fire weather outlooks. On the bottom half of the page are windows to severe weather climatology, public awareness and education material, case studies, and publications. Gone is the long menu list on the left hand side of the page that still is a feature of most NWS web pages.

The pages behind the home page still utilize the old web page design so you will still have to deal with the old menu structure until these are changed. However, the home page provides users with a clean "at a glance" overview and access to severe weather information.

One Good Thing About Spring Snow

2013-03-25T22:39:00.001-06:00

It's March 25th and the weather headlines look like they should be dated December 25th. Ground zero for Day 3 of this storm was an area from east-central Missouri through central Illinois. There was an initial burst of snow early Sunday morning that left up to 3 inches of snow in some locations, followed by several hours of no precipitation. In many areas the snow that fell overnight melted off as temperatures rose to the mid-30s. By late morning and early afternoon Sunday heavy snow was quickly spreading eastward across Illinois.

The Mesoscale Convective Discussion graphic at
11:52 a.m. CDT March 24 from the Storm Prediction Center

The atmospheric conditions were set up for a sustained heavy snow event. Low pressure was moving slowly eastward though southern Missouri, and warm, moist air aloft was streaming northward. This combined with instability and strong upward motion in the atmosphere to produce the heavy snow. Thundersnow was reported at a number of locations from St. Louis into central Illinois. Snowfall rates of 2 to 2.5 inches per hour occurred over a sustained period, and the result was widespread snowfall of 8 to 12 inches, with a number locations west and northwest of Springfield, IL reporting 15 to 18 inches of snow. The CoCoRaHS Observer at IL-SG-17 (Springfield 4.4 W) reported 16.5 inches of snow. This was a heavy wet snow, with snow-to-water ratios on the order of 9 to 1 (9 inches of snow to one inch of water).

48 hour snowfall accumulation map through 7:00 a.m. March 25 for central Illnois

Snow from this system also piled up from Indiana through southern Ohio and northern Kentucky to West Virginia. The storm still has a little punch left tonight, with Winter Storm Warnings in effect for the central Appalachians.

72 hour snowfall accumulation through 7:00 a.m. March 25

There is one good thing about a late spring snow, especially if you are tired of it. The higher March sun and temperatures above freezing quickly melt the snow on pavement reduce the snowpack. By late afternoon today where I live roads were mostly dry and you could tell that there already was a significant reduction in the depth of snow on the ground from the 10 inches I measured this morning.The hazard the next couple of nights will be refreezing of melting snow on roads as temperatures drop into the 20s overnight.

Major Storm Continues Slow March East

2013-03-24T13:16:00.003-06:00

A spring storm that already has dumped more than 12 inches of snow on eastern Colorado and another 4 to 8 inches in eastern Kansas and western Missouri will continue to affect the central and eastern portions of the country through Monday.

48-hour snow accumulation ending the morning of March 24.

Surface weather map at 10:00 a.m. CDT March 24

As of mid-morning the center of the sprawling low pressure system was located over the lower Ohio and Tennessee Valleys. Snow was falling from Missouri east through Illinois and north into Iowa. The system is being fed by an ample supply of moisture from the Gulf of Mexico, and that combined with the strong upper level system is producing heavy snow from eastern Missouri through central Illinois. CoCoRaHS observers have reported snowfall rates of 2 inches per hour. There is a possibility for thundersnow in the southern portion of the heavy snow band.

Snow accumulations will be heavy with this storm. There is a high probability of 4 inches or more from central Missouri to western Virginia, and a good chance of 8 inches or more within this band.from eastern Missouri into southern Indiana, as well as in the mountains in western Virginia. As of 1:45 pm CDT today 6 to 8 inches has already accumulated in west-central and central Illinois with heavy snow still falling.

24-hour probability of 4 inches or more of snow (left) and 8 inches or more of snow (right)

Winter storm warnings are in effect from Missouri eastward into Pennsylvania and eastern West Virgina.

Watches, warnings, and advisories as of 2:00 p.m. CDT March 24

Cooler, drier air plunging south in the wake of this system has raised the fire danger in southern Texas and red flag warnings are in effect today, Freeze warnings are in effect for northeastern Texas and northwestern Louisiana tonight.