Tornado, Hail Threat For Southern Plains

Severe weather, including a threat of tornadoes, hail and damaging winds, is returning to the Plains and could become more widespread beginning this weekend, lasting into next week from parts of Texas to the Midwest.

Through Friday

We do expect at least some isolated severe thunderstorms each day through Friday in parts of the U.S. But the threat is generally quite low to average for this time of year, with threats of mainly strong wind gusts and/or hail.

Here's where a few of those storms could flare up each day. The map below shows where rain and thunderstorms are currently happening along with any watches or warnings.

Wednesday: Parts of the Appalachians and interior Northeast from western Virginia and West Virginia to western Pennsylvania and central New York, parts of the Rockies from Utah to western Montana, the Texas Panhandle into northeast New Mexico and southeast Colorado.

Thursday: Parts of the Plains from western Illinois and Missouri to Kansas, northwest Oklahoma and the Texas Panhandle.

Friday: Many of the same areas as Thursday, except the Texas Panhandle.

Saturday

The risk for scattered supercell thunderstorms steps up a notch on Saturday afternoon and evening in the Central Plains, especially in the area shaded in the map below.

Large hail and severe thunderstorm wind gusts are possible as the storms fire up both along a dryline — a boundary between hot, dry air and warm, moist air — and a warm front. These thunderstorms may form into clusters that last overnight on the eastern edge of the area shown below (Iowa, Missouri).

(MORE: What Is A Dryline?)

Kansas City, Omaha and Wichita are among the cities in this threat zone Saturday.

Sunday

Sunday could see scattered severe thunderstorms from southern Minnesota to at least parts of Oklahoma, if not parts of northwest Texas.

The most widespread threat of thunderstorms appears to be in the northern areas shaded below. But all areas could see hail, damaging winds and a few tornadoes Sunday afternoon and evening.

One or more clusters of strong to severe thunderstorms with strong winds and heavy rain could persist Sunday night from the upper Midwest to the Southern Plains.

Cities like Minneapolis, Des Moines and Omaha need to watch out for Sunday’s weather.

Monday And Beyond 

Monday could be the most widespread threat of severe thunderstorms, possibly extending from Texas to Upper Michigan. Damaging winds, hail, tornadoes and flooding rain are all threats Monday and Monday evening.

Tuesday could also feature at least some severe storms from Texas and Louisiana to the Ohio Valley and possibly parts of the Northeast.

Wednesday, that severe threat could arrive in areas from New England to Virginia and parts of the Carolinas.

(MAPS: 7-Day US Forecast Rain)

Setup

We are in what is typically the peak tornado month across the Lower 48. No other month comes close on average, but we have seen some outbreaks this March and April.

Severe weather needs four main ingredients, which are all in plenty of supply in May.

You need shear, which is changes in wind speed and direction in the atmosphere. In May, the jet stream is still strong, providing plenty of shear.

You also need plenty of lift, which is provided by the series of cold fronts that often move across the county. Cold fronts bring cooler, dense air into contact with warm, less dense air. When that happens, that warm air cools and condenses into clouds that can form storms.

Then you also need instability. With spring well underway, daily heating provides plenty of instability, seen on the graphic below.

You also have to consider moisture, which the East has plenty of. Surges of moisture from the Gulf provide the fourth piece of the severe weather puzzle.

Stay weather aware as these areas are subject to expansion in the coming days.

Rob Shackelford is a meteorologist and climate scientist at weather.com. He received his undergraduate and master’s degrees from the University of Georgia studying meteorology and experimenting with alternative hurricane forecasting tools.