Community Collaborative Rain, Hail & Snow Network

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.

Three Weeks Into Spring

2013-03-20T11:05:00.000-06:00

Illumination of the Earth by the Sun
at the March equinox, as seen from the Sun.

The vernal equinox was at 6:02 AM CDT this morning, marking the start of astronomical spring. The minutes of sunlight will be increasing each day until the summer solstice on June 21st. As we all know, spring is the transition between the coldest period of the year (winter) and the warmest (summer). For those of us in the weather and climate field, spring actually started on March 1st and will continue through May 31st. Why do we use the calendar seasons instead of the the astronomical seasons? Generally it is much easier to compute averages and other statistics for a fixed number of days. The occurrences of the solstices and equinoxes can vary by a day or so each year making the seasons different lengths. And, it turns out that the meteorological seasons are closer to reality in general.. A study done in 1983 by a researcher at the University of Illinois (now with the National Center for Atmospheric Research) found that, for the mid-latitudes of North America, the seasons (in terms of temperature) more closely follow the calendar than the astronomical events. In fact, the astronomical seasons are only appropriate over the oceanic areas of the Southern Hemisphere. The response of the atmosphere to solar radiation lags by about 27 1/2 days at mid-latitudes. This means that during summer, for example, the peak heating would tend to occur during mid-July, 27 1/2 days after the summer solstice. Defining summer as June 1 to August 31 makes sense since mid-July is the midpoint of the meteorological summer (June, July, August). However, the calendar alignment isn't perfect for a number of reasons. For example, if we were to base the seasons in the Northern Hemisphere strictly on mean temperature, spring would be the period from March 9 to June 8.

March 1st or March 20th - this year some will argue, with good reason, that spring still isn't here!

If you have an interest in the astronomical you will find the U.S. Naval Observatory (USNO) web site a wealth of information. The USNO serves as the official standard of time for the entire United States. You can determine sunrise or sunset for any location in the country or find out when the phases of the moon will occur at any point in the future, or get the dates and times of the equinoxes and solstices. The Sky This Week describes what planets can be viewed and what other astronomical phenomena can be observed.

Trenberth, Kevin E., 1983: What Are the Seasons? Bulletin of the American Meteorological Society, Vol. 64, No. 11, pp. 1276-1282.

Ol' Man Winter Just Won't Let Go

2013-03-19T11:48:00.001-06:00

Here we are, almost three weeks into meteorological spring and much of the country is dealing with below normal temperatures and winter precipitation. Winter Storm Warnings are in effect from eastern New York through much of New England, and warnings and advisories are also in effect in the lee of the Great Lakes.

Warnings, watches, and advisories as of 1:00 p.m. EDT March 19.

The reason for this is a double-barreled low pressure system. The main center was located near the eastern end of Lake Superior while a secondary low was located just south of Long Island, NY.

Surface weather map as of 11:00 a.m. EDT March 19

CoCoRaHS new snowfall map for March 19

Snowfall amounts from 6 inches to more than a foot are possible in the warned areas of New England. As of this morning 6 to 10 inches of new snow had accumulated from southern Vermont and New Hampshire into eastern Massachusetts. The snow will continue to progress northward today and some of the highest storm totals are likely over Maine. With temperatures hovering near freezing this is one of those pain-in-the-back storms with heavy, wet snow.

Snow also blanketed northern Minnesota, much of Wisconsin, and the Michigan Upper Peninsula yesterday and last night. Snow continues today on the downwind side of the lakes.

24 hour snowfall ending the morning of March 19 in the upper Midwest

It's likely that winter will hang on for most of March. The latest 6 to 10 day outlook from the Climate Prediction Center which takes us through March 28 depicts a very high probability of colder than normal weather for the eastern one-half to two-thirds U.S. This is quite a contrast with the record warm March of 2012, and it is the type of thing that makes meteorology such a fascinating field.

CoCoRaHS observers will need to keep those snowboards out just a little longer.

SnowNews is Good News

2013-03-14T10:22:00.000-06:00

Snow Water Equivalent map for the central Rockies

Despite what your own feelings about snow may be, there is no question that winter snow in the western United States does more than provide scenic landscapes or downhill runs for skiers. The snow that piles up in the mountains of the western U.S. during the winter provides 50 to 80 percent of the annual water supply used for drinking, irrigation for agriculture, and water needed to maintain flows in rivers and streams for power generation.

The snow that falls each autumn through early spring eventually melts as the weather warms, and the runoff from the snow melt is captured in lakes and reservoirs or flows through streams and tributaries into major rivers such as the Colorado and Columbia. In order to be able to successfully manage this resource water managers need to have information on how much snow has accumulated, where it has accumulated, and most importantly the water content of the snow. Since the 1930s the Natural Resource Conservation Service (NRCS) of the U.S. Department of Agriculture has coordinated the Federal, state, and private efforts to measure and evaluate the snowpack in the western U.S.

If you think measuring the water content of 15 inches of snow with a CoCoRaHS gauge is difficult, measuring mountain snow tens of feet deep and its water content is a whole other ballgame. It takes specialized equipment, skills, and training to conduct these snow surveys. The monitoring of the mountain snow made strides in the late 1970s when the first SNOTEL (for snow telemetry) stations were put into operation. There are currently more than 730 SNOTEL sites in 11 states, including Alaska, that collect and transmit data in near real-time to a central computer in Portland, Oregon. Most are located in areas that are difficult to access.

A SNOTEL site in Truckee, California

The NRCS National Water and Climate Center and the Snow Survey and Water Supply Forecasting Program publish a quarterly newsletter called SnowNews. It's not just about snow, but there is plenty of snow-related content. It is a comprehensive newsletter that addresses water and climate related topics that impact all resource managers and stakeholders (e.g. commercial, government, tribal, non-government organizations). It has the latest news on web-related resources, what’s happening within NRCS water supply monitoring networks (SNOTEL covering the western states and SCAN, the Soil Climate Analysis Network, covering the nation). The just-released Spring 2013 issue features an article on the implications of the current drought in much of the U.S. and the seasonal water supply forecast for the western United States.

You can learn more about the importance of snow in the west and how this critical resource is monitored in Snow Surveys and Water Supply Forecasting.

What a Difference a Year Makes

2013-03-12T20:18:00.001-06:00

Last March at this time we were approaching the end of the first half of the warmest March on record in the contiguous U.S. This year, things are quite different through the first 10 days of March.

At this time last March the warmest part of the month, especially in the central U.S., lie just ahead. The highest number of temperature records occurred between March 14 and March 24, 2012. Maximum temperature and high minimum temperature records were not just broken - they were shattered by 10 and 20 degrees or more. By the end of March 2012 were more than 15,000 daily records for warmth broken across the country. So far in March 2013 there have only been 374 warm temperature records set.

A "Weather Active" March Weekend

2013-03-07T20:02:00.002-07:00

CoCoRaHS observers across much of the country will be busy measuring precipitation of one kind or another this weekend.

Western Atlantic surface map, 7:00 EST March 7

Those in southern New England are still dealing with the storm the moved off into the Atlantic late yesterday. This storm has intensified and stalled out over the Atlantic east of Virginia. A sharp ridge of high pressure to the east of this storm, and another intense low to the east of the high are blocking the eastward progression of this system. Strong easterly winds are pumping a steady supply of moisture into southern New England, much of which is falling as snow. Snow amounts from 6 to 12 inches are forecast across southern New England. This is a wet snow, and the weight of the snow combined with the high winds means that power outages will be likely. In addition, the winds are pushing the water toward coastal areas, and coastal flood warnings are in effect from Rhode Island to Maine through tomorrow morning.

In the west an upper level system will come ashore in southern California early Friday heading toward the southern Rockies. Rain and snow will accompany this system as it makes its way across the Southwest, and winter weather advisories, watches, and warnings are in effect for a number of western states. This southern system will merge with another disturbance in the Northern Plains, and by Saturday morning will be bringing snow to a large portion of the central and southern Rockies and the Northern Plains. Ahead of this system, strong southerly winds will feed moisture to fuel showers and thunderstorms eastward through the Midwest.

Quantitative Precipitation Forecast (QPF) from 7:00 p.m. EST March 7 to 7:00 p.m. March 10.

A March Lion

2013-03-06T21:47:00.000-07:00

Surface weather map at 7:00 p.m. EST March 6

The storm currently moving out to sea off the Virginia coast affected a large portion of the country this week. Tonight storm warnings are in effect offshore and gale warnings are in effect for Chesapeake Bay, Delaware Bay, and Long Island Sound. Coastal flood warnings are in effect for southern Virginia, Delaware, and the southern two-thirds of New Jersey as strong easterly winds gusting to 60 mph push water inland.

On Tuesday heavy snow fell in the Midwest, and overnight the snow shifted to the Appalachians. Snowfall reached 18 to 24 inches in the mountains of Virginia today with amounts tapering off toward the coast. The Washington DC metro area dodged a bullet, with only an inch or two of snow.

We're not done with this storm yet. The precipitation with this system will be spreading into southern New England tonight and Thursday, with some snow and rain hanging around through Friday. Heavy snow is possible at times Thursday from the Adirondacks to the southern New England coast.

Forecast map for Friday, March 8

Don't Put Away Those Snowboards Yet

2013-03-04T22:23:00.002-07:00

24 hour snow fall

A storm that moved from the Pacific into British Columbia on Saturday will be affecting the eastern half of the U.S. the next two days. It has already brought widespread snow to the Canadian Rockies, Montana, and the Dakotas with amounts from 12 to 18 inches. This evening the low pressure center was just south of Fargo, North Dakota, and by Tuesday evening the low is expected to be in the Ohio Valley. At rush hour on Wednesday the morning the storm should be located near Norfolk, Virginia. Winter storm warnings and winter weather advisories are in effect from the Dakotas to the mid-Atlantic coast.

Watches, warnings, and advisories in effect at 10:00 p.m. CST

Heavy snow will be the main feature of this storm, but freezing rain and sleet will be causing problems along the southern periphery of the storm track,

Probability of 4 or more inches of snow for the period from 6:00 p.m. CST March 4 to 6:00 p.m. March 5 (left), and from 6:00 p.m. CST March 5 to 6:00 p.m. CST March 6 (right).

A Late Winter in the Heartland

2013-02-28T12:17:00.000-07:00

Things were looking pretty dismal for snow lovers in the central U.S. through the end of January. With the exception of North Dakota and the Ohio Valley most of the region had received than 75 percent of normal snowfall by the end of January.

Two major storms rolled through the central U.S. in the past ten days producing copious amounts of snow. This last storm closely followed the path of the previous storm, laying down snow from Texas to New England.

72-hour snowfall ending the morning of February 28, 2013.

As of this morning, snow covers close to 50 percent of the lower 48 states.

Compared to the snowfall percent of mean map through January 31, the seasonal snowfall map as of this morning shows that much of the region has from 75 to 100 percent of normal snowfall or higher. However, there are some notable "holes" in the pattern east of the Rockies, in north central Iowa, and eastern Illinois through northern Indiana.

However, the snow season is not yet over. March can often bring significant snowstorms. The outlook for the first half of March is for a high probability for colder than normal weather across the central U.S. according to NOAA's Climate Prediction Center. It appears winter will hang on for a while longer.