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A look at weather extremes and the big-picture climate connections.

Deadly Texas Outbreak May Mark End of Tornado Drought

After months with record-low activity, the 2013 tornado season roared back with a vengeance on Wednesday as at least 10 twisters touched down across portions of north-central Texas, killing at least 6 and injuring dozens more. An even broader outbreak of severe weather, including the threat of more tornadoes, is forecast this weekend from North Texas to Missouri, gradually shifting eastward with time.


Eyewitness video of one of the Texas tornadoes on Wednesday.


The hardest-hit community on Wednesday evening was Granbury, about 40 miles southwest of Fort Worth. Hood County Sheriff Roger Deeds told the media that an entire neighborhood, consisting of 100-plus homes, was “heavily damaged to destroyed.”

There were reports that the Granbury tornado was as large as 1-mile wide, and aerial footage on Thursday morning revealed a broad swath of destruction. The town received a tornado warning 20 minutes in advance, according to Reuters. Preliminary reports from the National Weather Service show the tornado was at least an EF-4 on the Enhanced Fujita Scale, with winds of between 166 to 200 mph. Damage surveys have found homes that were completely swiped aside, and reduced to mere concrete slabs.

The Texas tornado fatalities were the second in the Lone Star State since 2007 — an unusually long stretch for a state that typically sees 8 deaths per year, based on statistics from 1961-1990. 

For the U.S., the deadly outbreak shatters the relative calm of t...


Rare May Snowstorm Annihilates Records in Midwest

A late spring snowstorm in the Midwest has shattered longstanding state snowfall records, with all-time state records for the month of May falling in Iowa, Minnesota, and Wisconsin. The snowstorm, which walloped the region with snowfall rates of more than an inch per hour at times on May 1-2, delivered 18 inches of snow in Blooming Prairie, Minn., 17.5 inches in Goodhue, and 15.5 inches in Owatonna.

Snowfall measurement in Eau Claire, Wis. 
Credit: NWS.

According to the Minnesota Climate Working Group, the state daily May snowfall record had stood at 12 inches, which was most recently set on May 3, 1954. The Working Group said that the snowstorm was extremely rare for southern parts of the state. 

“While May snowfalls are not uncommon in northern Minnesota, heavy May snowfall in southern Minnesota is rare. A quick scan of all historical Minnesota May daily snowfall totals greater than or equal to 3 inches indicates that May 1938 may have been the last time any southern Minnesota observer reported snowfall totals of similar magnitude,” the Working Group said on its website.

In Iowa, the 11 inches recorded at the town of Britt, which is in the north central part of the state, is also likely a state record. The 6.7 inches that fell in Des Moines was the city's biggest May snowstorm on record. In Wisconsin, 16.2 inches fell at Ashland, which also set a state record for the heaviest May snowstorm on record.

Also, up to 3 inches of snow fell in Arkansas, where measurable snow had never before been recorded...


Twin Cities Narrowly Escape Record May Snowstorm

Minneapolis-St. Paul narrowly missed a crushing, record-smashing snowstorm on Wednesday night into Thursday, as a band of extremely heavy snow stalled over the eastern suburbs of the Twin Cities. As of Thursday morning, some locations in southeast Minnesota had received more than 15 inches of snow, which is unprecedented this late in the year. Western Wisconsin was also seeing heavy snow, with more than a foot already on the ground and more to come throughout the day.

Records have likely been broken for single-day May snowfall in Iowa, Minnesota, and Wisconsin, and state snowfall records for the month of May have also been threatened in these states. The snow has been causing power outages by weighing down tree branches and power lines.

The snowy scene in Owatonna, Minn., on Thursday.
Credit: Twitter/Christian McKenzie

Had the storm hit only 50 miles or so further northwest, the Twin Cities would have been in the bullseye for at least a foot of snow, which would have shattered the all-time May snowfall record there, which stands at just 3 inches. That record, which was expected to be broken, may not be exceeded after all, since most of the snow has remained to the east of the Minneapolis-St. Paul International Airport, where official weather records are taken.

The freakishly heavy May snow totals in Minnesota, along with a barrage of similar storms during April, have helped to erase the long-term drought in the area, and in fact, have raised flooding concerns. As WeatherNation TV meteorologist Paul Douglas described the situation o...


Winter is Coming: Texas, Midwest Bracing for Cold

Winter is coming . . . back, that is.

A sharp cold front is ushering in some of the coldest temperatures on record for the month of May in the southern Plains and into Texas, with temperatures plummeting from the mid-90s on Tuesday in Amarillo, Texas, to the upper 20s on Wednesday night. Houston may be in line to set a record for the coldest May day on record if the low temperature on Friday or Saturday morning falls to 43°F.

These before and after images showing the profound temperature change as the cold air sags south, toward the Gulf of Mexico. Thee images come from computer-model projections:

Surface temperatures on Wednesday afternoon.

Forecast surface temperatures on Friday morning for the same region.

As an example of the cold front's strength, consider that as of 1 p.m. Central time on Wednesday, it was snowing and in the mid-30s in northwestern Iowa, while in southeast Iowa, on the warm side of the front, it was partly cloudy and near 80°F.

According to Houston Chronicle science reporter Eric Berger, Houston has only had one May day in recorded history with a temperature below 45°F.

The cold front may even be accompanied by light snow and sleet in parts of Oklahoma and the Texas Panhandle. Here's how the National Weather Service forecasters in Tulsa, Okla,. described the cold front in an online discussion (the all-caps format is NWS style): "AN ALMOST UNBELIEVABLY STRONG COLD FRONT FOR EARLY MAY WILL BLAST THROUGH THE AREA WED NIGHT AND VERY EARLY THURSDAY MORNING . . . AS FAR AS I KNOW . . . SNOW HAS NOT FALLEN IN MAY IN OUR FORECAST A...


Winter Is Finally Releasing Its Chilly Grip on the U.S.

After more than a month of colder-than-average weather in the U.S., warmer days are finally on the way. According to the Climate Prediction Center, which is part of the National Oceanic and Atmospheric Administration (NOAA), above-average temperatures are expected across the eastern U.S. from April 8-16, and above-average temperatures are also favored in the East, South, and Southwest for the April-June time period. 

Click image to enlarge. Credit: NASA.

The warmth will be especially welcome after an unusually cold March gripped much of the U.S., and affected Europe and parts of Asia as well. The above graphic from NASA tells the story, showing the colder-than-average temperatures between March 14-20 (compared to average of the same dates from 2005 to 2012). The image is based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite, and shows land surface temperature anomalies .

Areas with above-average temperatures appear in red and orange, and areas with below-average temperatures appear in shades of blue. Much of Europe, Russia, and the U.S. saw unusually cool temperatures, while Greenland was surprisingly warm for the time of year.

As Climate Central has reported, the long-lasting cold was related to a strong blocking High pressure system over Greenland, which was associated with a particular configuration of an atmospheric pressure pattern known as the Arctic Oscillation, or AO. The AO is a measure of the difference in relative air pressure b...