Relentless rounds of strong to severe thunderstorms have been plaguing the United States for almost three weeks straight, and more are on the way to start the workweek. A broad risk of damaging winds, destructive hail and a few tornadoes spans the Gulf Coast from Texas to Florida, and could be accompanied by flooding as well.
Severe thunderstorm watches were in effect Monday afternoon for parts of southern Texas, including Austin and San Antonio, while a tornado watch covered part of the Florida Panhandle. Large hail, possibly the size of baseballs, is the main concern in Texas, while areas farther east will see scattered wind gusts topping 60 mph.
And that’s just the start. Tuesday and Wednesday look comparatively quiet from a severe weather standpoint, but more storms are probable Thursday. A general pattern change, meanwhile, could support more widespread severe storms into the final 10 days of May, though confidence remains low in the timing and placement of specific hazards.
Most recently, an outbreak of severe storms between Monday and Friday of last week brought widespread severe weather from Texas to southern New England. At least 23 states recorded tornadoes, 15 of which reached EF2 strength or greater on the 0-to-5 Enhanced Fujita scale for intensity. Hail the size of melons pummeled areas just west of Austin on Thursday, and two tornadoes in Tallahassee even merged early Friday.
May is historically the most active month for severe weather, and this year is proving no exception. So far this year, despite an above-normal number of tornadoes, storm-related fatalities have been below-normal because of accurate forecasts and warnings and when and where twisters have hit.
Monday’s storms
Risk area
A broad Level 3 out of 5 risk for severe weather stretches from San Antonio to Panama City, Fla. It includes Houston and Austin, the Interstate 10 corridor though southern Louisiana and Mississippi, and Mobile, Ala.
A Level 2 risk, meanwhile, encompasses a surrounding area that includes Corpus Christi and Waco in Texas, Shreveport and New Orleans in Louisiana, and Tallahassee.
Hazards
In western portions of the risk area, mainly in Texas along and east of Interstate 35 from Waco to San Antonio, storms pose mainly a large hail threat. Severe storms began to blossom Monday morning, and a few contained hail the size of golf balls or larger. Some hail may grow to as big as baseballs during the afternoon, when heating bolsters instability, or storm fuel, even more.
The environment won’t support widespread tornadoes because winds won’t be changing direction that much with altitude, but a few are possible. Hail will be the bigger threat.
Farther east across the rest of the risk area, storms will form beneath a jet stream, or river of strong winds aloft, that’s moving swiftly from west to east. Any storms that grow tall enough will tap into those strong winds and mix momentum to the surface in the form of damaging gusts. An isolated tornado is also possible, especially near a warm front draped along the coast. Warm fronts impart extra spin.
Flooding
Flood watches also expand from Waco through Beaumont and Port Arthur in Texas all the way east to southwest Georgia and the Florida Panhandle.
Storms surfing the jet stream will move repeatedly like rail cars along a track along the west-to-east warm front. That means continuous downpours and the potential for flooding.
A few storm totals of 3 to 5 inches of rain are possible, mainly within 50 to 100 miles of the Gulf Coast.
Looking ahead
Severe weather risks diminish somewhat after Monday. On Tuesday, a few severe storms are possible across the Southeast with the threat of gusty winds and small hail; that threat will shift into the coastal Mid-Atlantic on Wednesday, with a few additional storms over the Texas and Oklahoma panhandles.
By Thursday, a new disturbance will approach and could induce severe weather across the southern Plains.
Otherwise, more storms are probable next week as the pattern becomes increasingly favorable for severe weather. A large trough, or jet stream dip, in the West will allow insurgences of cold air to slide over the Plains. Each one will clash with warm, moist air from the south, brewing storminess.
