Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0352 AM CDT Sun Sep 05 2021 Valid 081200Z - 131200Z ...DISCUSSION... An upper trough will persist over the eastern U.S. through Day 6/Fri. At the surface, a cold front will shift east/southeast across the Ohio Valley on Wed/Day 4 and into the Mid-Atlantic/Northeast vicinity by Wednesday night. Increasing southerly low-level flow ahead of the front will transport moisture northward into parts of the Northeast. Forecast guidance currently indicates quite a bit of precipitation ongoing both along the front in the Ohio Valley vicinity and in the warm advection regime across New England. Some severe potential is possible given areas of favorable boundary-layer moisture amid moderate vertical shear. However, degree of destabilization remains a concern, as well as timing of the surface cold front. These uncertainties will preclude severe probabilities across portions of the Northeast at this time, though an area may become necessary in subsequent outlooks. The surface cold front should shift offshore from the Atlantic coast on Thu/Day 5. Severe potential appears low for much of the rest of the period. A lower-amplitude upper pattern will emerge, with richer Gulf moisture becoming cut off, as surface high pressure builds over the central U.S. through Fri-Sat/Day 6-7. Read more LIVE: spc.noaa.gov
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