SPC 0700Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 AM CST Sun Nov 22 2020 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms appear unlikely across the contiguous United States on Monday. ...Synopsis and Discussion... A pair of large-scale upper troughs will move eastward across the CONUS on Monday. Strong low-level warm/moist advection ahead of the upper trough over the eastern states may support just enough elevated instability to generate isolated lightning flashes with convection occurring across parts of Long Island into coastal New England. Even with mid to perhaps upper 50s surface dewpoints advecting into parts of coastal MA Monday morning/early afternoon, it appears that meaningful surface-based instability will struggle to materialize ahead of an eastward-moving cold front. Still, given the strength of the low to mid-level south-southwesterly flow, a strong convective wind gust cannot be completely ruled out. However, owing to limited forecast instability, this potential currently appears too low to include any probabilities for severe wind gusts across RI and eastern MA. Thunderstorm potential should shift quickly east-northeastward and offshore through the day in tandem with the progression of the upper trough. The upper trough over the western CONUS will likewise progress eastward, with the southern portion of this trough closing off near the Four Corners late Monday night. Although moisture is expected to remain quite limited, cooling mid-level temperatures and strong forcing for ascent associated with the upper trough/low should support isolated thunderstorms across parts of the southern/central Rockies through the period. At the surface, lee cyclogenesis will occur across the central High Plains, with modest low-level moisture return occurring across portions of the southern/central Plains ahead of the developing low. Isolated thunderstorms may also occur across this area, mainly Monday night into early Tuesday morning. Instability is forecast to remain fairly weak (MUCAPE generally 500 J/kg or less), with any storms that form likely remaining elevated. ..Gleason.. 11/22/2020
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