Severe weather risk for the Upper Midwest

Severe weather is currently active over the Northern Plains with a tornado watch and multiple severe thunderstorm watches active this evening.

Summary

A potent shortwave trough is moving across the Northern Plains this afternoon and is expected to move towards the Upper Mississippi Valley by Friday.  Currently, the greatest threat for severe weather exists from the  Black Hill region of the Dakotas East and Southeast across the Mid-Missouri Valley.  Strong and damaging wind gusts, very large hail and a few tornadoes are expected.   Multiple Mesoscale Convective systems from these severe storms will continue to progress further East from the Midwest down to the Carolinas  and Georgia.

severe outlook

Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MODERATE 35,708 282,582 Mitchell, SD…Pierre, SD…Yankton, SD…Vermillion, SD…
ENHANCED 90,604 4,130,773 Nashville, TN…Des Moines, IA…Sioux Falls, SD…Clarksville, TN…Sioux City, IA…
SLIGHT 214,768 10,921,413 Omaha, NE…Lexington-Fayette, KY…Lincoln, NE…Savannah, GA…Cedar Rapids, IA…
MARGINAL 372,120 43,514,822 Columbus, OH…Memphis, TN…Charlotte, NC…Kansas City, MO…Cleveland, OH…

Tornado Watch Active

tornado outlook

THE NWS STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR

Northern Nebraska, Western South Dakota and Far Northeast Wyoming until 10 PM CDT.

 

A few more tornadoes are likely with a couple of intense tornadoes possible.  Currently, there is an active Tornado Warning for a tornado on the ground in cherry County Nebraska.  Widespread Large hail and isolated very large hail to 3.5 inches in diameter likely and widespread damaging winds likely with isolated gusts to 80 MPH possible.

Intense thunderstorms, including Supercells and Supercell clusters have formed over the watch area and are moving towards the Eastern portion of the watch area.  South of this watch area, the Tornado risk is much smaller and a Severe Thunderstorm Watch is in effect until 10 PM CDT.  Squall line development is expected from the storms further north in the Tornado watch area.  This squall line will move into Central and Southern Nebraska and move toward the Southeastern and Eastern portions of this watch area.

tornado outlook

Further North,   a line of storms from Montana has moved into the Dakotas.  The severe thunderstorm watch for this area is slowly being cancelled from west to East but remains in effect for the Western Dakotas until 9 PM CDT.

 

Severe Thunderstorm Watches are in effect for a small portion of Central Tennessee, this watch should be cancelled shortly.

 

Thursday Severe Risk

severe outlook

Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 120,618 9,748,278 Minneapolis, MN…Des Moines, IA…Cedar Rapids, IA…Springfield, IL…Peoria, IL…
SLIGHT 206,214 34,063,611 Chicago, IL…Indianapolis, IN…Milwaukee, WI…Omaha, NE…St. Louis, MO…
MARGINAL 347,083 42,004,487 Detroit, MI…Columbus, OH…Charlotte, NC…Nashville, TN…Kansas City, MO…

A complex setup is set for Thursday with multiple rounds of convection expected across a large region.  Clusters of severe thunderstorms will be likely within a Mesoscale Convective System over Iowa and  Southern Minnesota.  Downstream of this area, dew points  in the 70s will combine with daytime heating to form a moderately to strongly unstable air mass through the day. This set up should yield multiple clusters of intensifying storms from the late morning into the afternoon across parts of the Midwest.

In the wake of the morning activity, low level moisture should return on the Southwesterly flow underneath the elevated mixed layer.  Moderate to extreme mid-level cape could help generate another mesoscale convective system Thursday evening in the Iowa, Missouri, Illinois border area.

Farther north, strong mid-level winds associated with the trough will overspread Minnesota where strong instability already exists.  While instability does decrease the further north you go, scattered to widespread storms should form mid-afternoon to early evening.  Deep shear will be sufficient for organized strong clusters and embedded supercells.  Large hail and strong winds will be the primary risks.

Robert Millette

Staff Meteorologist

Firsthand Weather