SPC 0700Z Day 2 Outlook

Day 2 Outlook Image

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1230 AM CST Sun Nov 22 2020

Valid 231200Z - 241200Z


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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