Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0320 AM CST Sat Feb 27 2021 Valid 021200Z - 071200Z ...DISCUSSION... A series of upper shortwave troughs will migrate across the southern tier of the U.S. during the Day 4-8 period. The first in this series, located over the southern/central Plains on Day 4/Tue will shift eastward to the Carolinas/Mid-Atlantic vicinity through Day 5/Wed. At the surface, a weak low will develop near coastal LA on Tuesday, shifting east/northeast across the southern states and offshore the Carolinas by Wednesday evening. This will bring a cold front across the southeastern U.S. and widespread showers and thunderstorms are expected. Much of this activity is expected to remain elevated, with instability limited and shear relatively modest. High pressure will settle across the eastern half of the U.S. Day 6/Thu, with the surface cold front continuing southward into the northern Gulf and FL Straits vicinity. Late in the period, a second upper shortwave trough/closed low is expected to develop eastward across the southern Plains and Gulf coast vicinity around Day 7/Fri-Day 8/Sat. Guidance varies quite a bit in the evolution of this system, with some medium range guidance digging the trough fairly far south into the Gulf. This could limit northward moisture return, keeping any severe potential offshore from the central Gulf coast. However, this could bring an increase in severe potential to the FL Peninsula over the weekend. Given large spread, uncertainty is too great to include severe probabilities at this time.
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