April 12-13, 2018: Plains Severe Weather Threat

After weeks of winter weather and heavy snowfall; the first threat for widespread thunderstorms and severe weather, across the Plains, looks to occur this week. A powerful low pressure system will push out of the Colorado Rockies on Thursday and intensify as it pushes into the Upper Midwest. Strong southeast winds ahead of this low pressure system will transport warm/moist air northward across Texas, Oklahoma, into Kansas.

This will set the stage for moderate instability to develop east of a dry line across Central/Eastern Kansas into Oklahoma during the day on Thursday. This coupled with strong wind shear in the low and mid levels, will produce an environment conducive to severe weather including supercell thunderstorms.

However one major fly in the ointment is that temperatures in the mid levels will be increasing throughout the afternoon/evening hours producing what we call a “capping inversion”. This could prevent thunderstorms from developing at all during the day on Thursday, this is something that will have to be watched as we go throughout the week. Storms will form sometime during the evening/overnight Thursday though in the presence of strong forcing associated with the system coming out of the Rockies. If storms are able to form during the day in presence of a strong capping inversion, then tornadoes, large hail, and damaging winds will all be possibilities….however if storms form during the evening/overnight hours then the threat may be more confined to large hail as the storms would be more elevated in nature.

On Friday, the storm system pushes eastward into Iowa/Minnesota with strong southerly flow ahead of it into Illinois/Indiana which brings a similar environment that was across Kansas/Oklahoma, to these areas.

The system will be less organized on Friday however and at this juncture its too soon to say exactly what could or will happen in these locations, just know that severe weather will be possible Friday afternoon/evening somewhere from Illinois down to Arkansas.


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