Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sun Sep 24 2023 Valid 271200Z - 021200Z ...DISCUSSION... ...Wednesday/Day 4 to Friday/Day 6... From Wednesday to Friday, an upper-level low is forecast to move northeastward across the Great Lakes region, as an upper-level ridge moves through the north-central U.S. At the surface, high pressure will likely remain in place across the eastern third of the nation. Weak instability is forecast to develop along and near an upper-level trough in the Ohio and Tennessee Valleys on Wednesday and Thursday, where scattered thunderstorm development will be possible. Further west, across the northern Plains, southwest mid-level flow is forecast to develop on Thursday and Friday. In response, low-level moisture will likely return northward into the northern Plains, where a pocket of moderate instability could potentially develop by Friday afternoon. Isolated to scattered thunderstorms, along with a marginal severe threat, would be possible Friday or Friday night as destabilization occurs and low-level flow increases. ...Saturday/Day 7 and Sunday/Day 8... From Saturday into Sunday, an upper-level trough is forecast to move into the western U.S. as mid-level flow becomes more south-southwesterly across the north-central U.S. Model forecasts suggest that a pocket of moderate instability will be in place across the Dakotas on Saturday, and to a lesser extent on Sunday as well. Although large-scale ascent will probably be weak across the region over the weekend, isolated to scattered thunderstorms could still develop, especially if a boundary moves through the region, as is suggested by some solutions. A severe threat would be possible, especially on Saturday afternoon and evening when instability is forecast to be maximized. At this time, predictability is low concerning any potential scenario.
