Severe Weather has moved into the Great Lakes region and will move into the Central and Southern Plains Tuesday.
Currently, a Severe Thunderstorm Watch exists for the Chicago area extending towards Milwaukee up into Wisconsin and down throughout Northern Illinois. Multiple reports of hail have occurred in this region as this system is slowly combining with the new system moving out of the Rockies. Additional Severe Thunderstorms are possible with activity expected to lessen after nightfall.
Tuesday Severe Weather Update:
Significant Severe Thunderstorms are forecast to occur across parts of the Southern and Central Plains Tuesday afternoon into the night time hours. Tornadoes, some strong and long lived, will be possible in addition to Very Large to Giant Hail and Strong Damaging Winds.
A deep upper level trough currently extends from the Pacific Northwest into the Western Great Basin. This trough will continue eastward today and move from the Four Corners region into the Central Plains on Tuesday. A shortwave trough moving along this trough, will move through the region overnight and lead to surface cyclogenesis, the development or strengthening of cyclonic circulation in the atmosphere, this afternoon and overnight. Low-level flow associated with this cyclogenesis will persist overnight and bring ample amounts of low-level moisture into the Plains overnight and Tuesday. Another shortwave moving through and into the Southern Plains on Tuesday will help enhance this moisture flow, leading to dewpoints in the mid to upper 60s
The second shortwave is expected to form into a surface low across the Central Plains Tuesday afternoon with a dryline forming over the Central Plains. The Thermodynamic environment ahead of this dryline will see temperatures in the upper 70s to low 80s with the aforementioned mid to upper 60s dewpoints. Very strong instability and CAPE (Convective Available Potential Energy) will be more than supportive for Severe Thunderstorms. While the overall wind shear profiles are good, low-level flow is expected to be weaker than what is generally associated with numerous long lived tornadoes, so the Storm Prediction Center has not issued a High Risk for the Plains at this time. With that said, numerous and wide spread severe thunderstorms are still anticipated with all severe threat possible from the Red River up through South Central and Southeastern Nebraska.
Further south of there, convective coverage will not be as widespread, as southerly mid-level flow favors a linear squall line type of development vs discrete supercellular development north of the Red River. This is not to say that supercells are not expected in this region, just that they will not be as numerous and that squall line and cellular cluster development will be more widespread. While some sections of the Southern Plains may see Isolated to Scattered coverage, all severe hazards are still possible.
As you can see from the maps, the moderate risk has been slightly extended from the earlier maps posted with the forecast today. This area may be slightly expanded as more information on thermodynamic profiles increases throughout Tuesday morning. Based on the second map, significant severe weather can be expected all the way to Southern Texas. This should serve as a reminder that even though you are only in the enhanced or slight regions, significant severe weather can occur, it just won’t be as widespread. Anywhere in the shaded region on the second map should be prepared for significant severe storms.
The Tuesday morning forecast for Firsthand Weather will have a delayed release to attempt to bring the latest Severe Weather information we can bring you and we will continue to monitor this situation and model guidance overnight tonight. I hope to have 2 updates out Tuesday, one with the regular but delayed forecast, and another early Tuesday afternoon as things get started.