Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CST Tue Dec 08 2020 Valid 111200Z - 161200Z ...DISCUSSION... A large-scale upper trough with several embedded shortwave troughs will slowly migrate across the Plains and central U.S. Days 4-5/Fri-Sat. Strong southwesterly flow amid height falls will result in a strengthening surface low developing northeast from the southern Plains early on Friday to the lower Great Lakes vicinity by Day 6/Sun morning. Low level Gulf return flow will spread moisture northward ahead of a cold front attendant to the low. Better-quality moisture will be confined to the TX Gulf Coast eastward to the lower MS Valley and thunderstorms are likely to increase by Friday afternoon along the front. Some low-end severe threat could develop from east TX into the lower MS Valley through Saturday, but uncertainty remains regarding how much destabilization will be able to occur whether moisture return will be ill-timed with the frontal passage/strongest forcing. Beyond Day 5/Sat, medium range guidance varies greatly in the evolution of the larger-scale trough over the central U.S. and predictability is low.
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