After nearly a week of quiet following an outbreak of severe weather that tore through the Interstate 35 corridor in Texas and dropped a deadly EF3 tornado in downtown New Orleans, the atmosphere is set to cook up a renewed severe weather threat.

Dangerous thunderstorms with large hail, damaging winds and a few tornadoes are likely between Tuesday and Thursday as a potent upper-air disturbance swings from the Plains to the Mid-Atlantic. This same weather system is bringing heavy rain and flooding to parts of Southern California on Monday

If that’s not enough, dry, windy air ahead of the storm may result in a flare-up of fast-moving fires from western Texas to southwest Kansas on Tuesday.

As the storm system sweeps across the country, Wednesday is predicted to be the nastiest day for thunderstorms and could feature a squall line with damaging winds and embedded tornadoes that blows through Mississippi and Alabama. An isolated strong tornado is possible if additional rotating thunderstorms develop ahead of the mainline, though there is high uncertainty.

The severe thunderstorm risk commences on Tuesday in the Plains, and should end Thursday evening in the Mid-Atlantic.

March often kicks off a three-month stretch punctuated by seemingly ceaseless barrages of severe thunderstorms and tornadoes across the Lower 48. April marks the start of peak tornado season, when a seasonal clash — characterized by warm air from the Gulf of Mexico waging war with chilly lingering wintertime air — brews violent storms.

There are already signs that April and May could be more active than average, meaning severe thunderstorm and tornado chances aren’t likely to flatline any time soon.
Setting the stage for storms

On Monday morning, a counterclockwise swirl could be seen on water vapor satellite imagery moving ashore in Southern California. It was bringing heavy rain and mountain snow.

That marks a shortwave — a lobe of high altitude cold air, low pressure and spin. It will shift east with time and help energize a surface low dropping from the Intermountain West into the central Plains.

On Tuesday, southerly and south-southeasterly winds will be on the increase. That’ll bring in warm air loaded with Gulf of Mexico moisture into the eastern Plains. As temperatures at high-altitudes cool, parcels of air at ground level will begin to rise and form strong to severe thunderstorms.

Meanwhile, the shortwave is nestled within a dip in the jet stream, a river of swiftly-moving air in the upper atmosphere. That wind at upper levels will help amplify wind shear, or a change in wind speed and/or direction with height. That means any thunderstorms that tower through multiple levels of atmosphere will derive a twisting force that will foster rotation.