SPC AC 200042
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 PM CDT Tue Oct 19 2021
Valid 200100Z - 201200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
NE...SOUTHEAST SD...SOUTHWEST MN...NORTHWEST IA...
Thunderstorms posing a risk for isolated severe hail may occur later
this evening and overnight across parts of northern Nebraska,
southeast South Dakota, northwest Iowa, and southwest Minnesota.
...Northern NE...Southeast SD...Northwest IA...Southwest MN...
A closed mid/upper level low near the CO/WY border this evening is
forecast to move northeastward towards the Sand Hills region of NE
overnight, as an attendant surface low moves into eastern NE.
Steepening midlevel lapse rates and increasing moisture in the
850-700 mb layer will support MUCAPE of 500-1000 J/kg (locally
higher) late this evening into the overnight hours. Increasing
large-scale ascent will support scattered elevated thunderstorm
development through late tonight, generally near and north of a
surface boundary draped from northeast NE into northwest
MN/southwest MN. Effective shear of greater than 30 kt may favor
some storm organization, and isolated large hail will be possible
with the strongest cells.
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