Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0352 AM CST Tue Nov 17 2020 Valid 201200Z - 251200Z ...DISCUSSION... Quasi-zonal upper level pattern on Day 4/Fri will give way to a somewhat more amplified and progressive pattern beginning Days 5-6/Sat-Sun. During this time, a series of mid/upper shortwave troughs will migrate eastward from the western U.S. and into the Plains. Strong surface high pressure will persist across much of the U.S. east of the Rockies, resulting in dry, stable conditions. However, a weak lee trough over the southern High Plains will allow southerly low level flow to transport modest Gulf moisture northward across the southern Plains ahead of a stalled front draped across KS and into the lower MS/OH Valley vicinity. Surface dewpoints in the 50s to low 60s F could reside across parts of KS/OK/TX, but cloudiness and heavy rain showers will limit instability. While thunderstorm activity is possible for portions of the southern Plains region during the weekend, severe potential appears limited. Quite a bit of spread exists in forecast guidance beyond Day 6/Sun. There is general agreement that another larger-scale trough will eject eastward across the Rockies and into the Plains/Central U.S. early next week. However, too much uncertainty remains at this time scale given large spread in forecast guidance to ascertain severe potential across parts of the southern U.S. around Days 7-8/Mon-Tue.
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