Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0313 AM CST Wed Feb 10 2021 Valid 131200Z - 181200Z ...DISCUSSION... An arctic airmass will envelop much of the CONUS through at least Day 6/Mon. A series of upper troughs will allow reinforcing shots of cold air to spread southeast across the Plains and Midwest. While a cold and dry airmass will settle across the Southeast U.S., southwesterly deep-layer flow will prevail, maintaining weak warm advection across the region with a surface boundary extending across the northern Gulf of Mexico and northern FL for much of the period. This will allow for periods of showers and thunderstorms across parts of the Southeast, but severe potential appears low. The exception may be around Day 6/Mon or Day 7/Tue when a shortwave trough is forecast by some guidance to develop eastward across northern/central Mexico and into the Gulf, before lifting northeast toward the Mid-Atlantic by the end of the period. If this occurs, surface cyclogenesis across the lower MS/TN Valley vicinity could result in a favorable warm sector overlapping with strong shear and upper forcing across parts of the Southeast ahead of another strong cold front. Medium-range guidance currently differs in timing and intensity of these features, resulting in low predictability, but severe probabilities could be needed in future outlooks if confidence in this scenario increases.
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