Tornado Digest: Major outbreak to close April, and the first May threat mid-week

EF-4 Vilonia, AR tornado. (Virginia Millwood via Twitter)

Looking back at the week of April 27-May 3, and a brief look ahead.

After a very quiet April, tornadoes — including the first two violent EF4s of the year — ravaged parts of the southern United States to close the month.

Two days in a row featured “high risks” from the Storm Prediction Center, something that only happens every other year or so.

When all was done, roughly 75 or more tornadoes touched down in one of the more active events over the past few years. Among those numbers, at least five killer tornadoes touched down in Arkansas, Mississippi, Alabama and Tennessee.

Tornado activity across the U.S. April 27-May3. Note: A tornado briefly touched down in Washington state and is not shown.

April 27 – Eastern Plains and the Mid South

The week begin with the start of several days of tornado activity across the southern United States as a strong upper-level trough cutoff from the steering flow and continued to send waves of severe weather episodes across the region. On Sunday the 27th, tornado activity was not terribly widespread, with only about a dozen observed. What lacked in numbers was made up in intensity. One EF4 plowed through Mayflower and Vilonia, Arkansas among other spots to the northwest of Little Rock. 15 were left dead in the event.

HIGH risk up for part of Arkansas. 30% hatched tornado probability area. pic.twitter.com/Ajd7ppiDh6

— U.S. Tornadoes (@USTornadoes) April 27, 2014

Strong tornado today in southeast Kansas, the debris in the air was a destroyed church #KSwx #MOwx pic.twitter.com/Ct84WFR0R9

— Chad Cowan (@stormtimelapse) April 28, 2014

Tornado in Vilonia pic.twitter.com/j0zhrxZqv5

— virginia millwood (@mlwdgrl1975) April 28, 2014

April 28 – Mid South

The second high risk day in a row, this time shifted a bit to the southeast. When it comes to a traditional tornado outbreak featuring a handful or more supercells almost all dropping tornadoes, this was it. Though much smaller in scale than the April 27, 2011 outbreak, some of the same areas were hit. Over 40 tornadoes have been confirmed in Mississippi and Alabama alone, including an EF4 in Winston County, MS. Four more killer tornadoes occurred on this day, with another 15 people lost.

HIGH RISK area features 30% tornado probabilities. #mswx #alwx http://t.co/IdRk4i80j9 pic.twitter.com/rrfy1jF3GZ

— U.S. Tornadoes (@USTornadoes) April 28, 2014

Tornado Outbreak on going in MS & AL pic.twitter.com/fYADAD8DSD

— Brad Panovich (@wxbrad) April 28, 2014

Insane #tornado today in #Mississippi! Near Louisville, MS. #TornadoOutbreak pic.twitter.com/nBFzHfRInB

— Weatherstorm.net (@wxstorm) April 29, 2014

April 29 – Southeast

Tornadic storms were mainly confined to North Carolina on this day, and overall the threat materialized on the low end of potential which was a good thing given what already happened with this system. Several brief and weak tornadoes touched down in NC, and also down in the Florida panhandle. A cold-core tornado was confirmed in Illinois.

Another shot of that funnel cloud in Stedman that a viewer just sent me #ncwx pic.twitter.com/4GGeOiNTOD

— Nicole Carr (@NicoleCarrABC11) April 29, 2014

3d view of storm now producing a tornado in Sampson County NC. pic.twitter.com/thUdgYNozG

— U.S. Tornadoes (@USTornadoes) April 29, 2014

April 30 – Mid-Atlantic

Some tornado risk was expected to continue into the mid-Atlantic to close the month, and there was a tornado watch issued for parts of North Carolina and Virginia. The story of the day was mainly flooding and continual rain, which partly helped keep things from bubbling too much with atmospheric stability over a good chunk of the region.

Tornado-warned cell in VA just West of I-95. #vawx pic.twitter.com/yYm4VFAJs4

— Christina Anthony (@Christina_WWAY) April 30, 2014

Non-rotating wall cloud from tornado-warned storm earlier today. Northeast of Jarratt, VA. pic.twitter.com/VllzvF2Stn

— Mark Ellinwood (@markellinwood) May 1, 2014

Another trough mid-week

The last storm system mostly wiped the country clean of moisture, and storms have been few and far between since.

But, it’s May, and that means we’re into the average peak of the tornado year. No gigantic systems are in the offing, though an energetic mid-level trough should push out into the central U.S. during the week. Once it does, at least some severe weather is likely. And it’s hard to get a system with no tornadoes in May…

May 5 0z GFS 500mb height and vorticity shows a trough about to eject into the Plains late Wednesday. (Weatherbell.com)

As of now, there are some timing issues for both days with the best look on this system. It’s a little slow to move into the Plains for a big day on Wednesday and a little fast for Thursday. It does not appear this will be a major tornado outbreak, but perhaps the zone most at risk lies from the eastern Plains into the Midwest.