Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0345 AM CDT Sat Jun 19 2021 Valid 221200Z - 271200Z ...DISCUSSION... A highly amplified upper trough should continue moving east-northeastward across the eastern CONUS on Day 4/Tuesday. A moist low-level airmass will likely remain in place ahead of a surface cold front, and some severe threat may continue across parts of the East Coast with any storms that develop Tuesday afternoon before moving offshore. At this point, too much uncertainty remains regarding the evolution of the upper trough and timing/placement of the front to include a 15% severe area. Regardless, a threat for at least isolated damaging winds will probably continue on Tuesday, and low severe probabilities will likely need to be included in a later outlook. Upper-level ridging centered over the Rockies on Day 5/Wednesday may be suppressed as multiple shortwave troughs move east-southeastward through the end of next week across Canada and perhaps into parts of the northern Plains and Upper Midwest. Some medium-range guidance suggests that mid-level northwesterly flow may strengthen by late next week from portions of the northern/central Plains into the Midwest and mid MS Valley in association with these upper troughs. Low-level moisture is also forecast to gradually return northward across these regions in the latter half of next week. This synoptic setup is typically favorable for severe MCS development, and the forecast thermodynamic and kinematic environment does appear supportive, mainly from Day 6/Thursday onward. Still, there is far too much uncertainty regarding the progression of the possible shortwave troughs and possible MCS development each day to include 15% severe probabilities at this extended time frame. Read more LIVE: spc.noaa.gov
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