Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0354 AM CDT Mon Oct 19 2020 Valid 221200Z - 271200Z ...DISCUSSION... ...Thursday/Day 4 to Saturday/Day 6... On Thursday, an upper-level trough is forecast to move across the Intermountain West as southwest flow remains over the central U.S. A cold front is forecast to advance southeastward into the Upper Midwest as a low-level jet moves into the region from the southwest. Thunderstorms will be possible along the western edge of the low-level jet from the central Plains northeastward into the upper Mississippi Valley from late afternoon into the evening. Instability is forecast to be weak suggesting any severe threat would remain marginal. On Friday and Saturday, the medium-range models move a cold front southeastward across the mid Mississippi Valley and into the southeastern U.S. Thunderstorms are expected to develop along parts of the front both Friday and Saturday afternoon. However, instability is expected to be weak which will again keep any severe threat marginal. ...Sunday/Day 7 to Monday/Day 8... Model solutions sharply diverge late in the Day 4 to 8 period. Some solutions show an upper-level trough in the western U.S. with others having the trough further to the east into the Great Plains. If the model solutions with the trough further east verify, then thunderstorms would be possible ahead of the trough on Sunday and Sunday night from the mid Mississippi Valley and Ohio Valley southwestward to the southern Plains. Under this scenario, the front would move southeastward across the Ohio and Tennessee Valleys on Monday. Isolated severe thunderstorms would be possible along parts of the front on Monday. However, the models are forecasting weak instability in most areas suggesting any severe threat would be marginal.
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