Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0348 AM CST Fri Nov 20 2020 Valid 231200Z - 281200Z ...DISCUSSION... Organized severe thunderstorm potential appears low across the CONUS on Day 4/Monday as a large-scale upper trough shifts eastward from the western states to the Plains. Lee cyclogenesis should occur over the central Plains ahead of the amplifying upper trough, with some low-level moisture return occurring over the southern Plains. As the southern portion of the upper trough consolidates and ejects eastward across the southern Plains into the lower MS Valley and Southeast from Day 5/Tuesday into Day 6/Wednesday, some severe thunderstorm potential could materialize across parts of these regions. At this point, instability appears fairly limited, which should keep any severe threat isolated/marginal. The upper trough may outpace the limited low-level moisture by Day 7/Thursday across parts of the eastern states, which suggests that the severe risk will probably be lower compared to prior days. By the end of next week, large differences emerge in medium-range guidance regarding the evolution of another upper trough over the western/central CONUS. Depending on this trough's amplification and the degree of low-level moisture return, it appears possible that a severe threat could develop across parts of the southern Plains around Day 8/Friday. Regardless, predictability remains very low at this extended time frame.
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