SPC 1200Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1115 PM CST Sun Nov 22 2020

Valid 231200Z - 241200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Scattered thunderstorms are possible across portions of New England
and over areas of the Rockies/Plains.

...New England...

Strong mid-level speed max is digging southeast across WI late this
evening. This feature will encourage height falls across New England
as a strong short-wave trough advances into the upper OH Valley by
the start of the day1 period. In response, sustained southerly
low-level flow will allow modified boundary-layer moisture to
advance inland across coastal southern New England such that weak
surface-based buoyancy should materialize during the first few hours
of the convective period. Forecast soundings from southeast
CT/RI/southeast MA exhibit upwards of 300 J/kg SBCAPE within a poor
lapse rate environment that is strongly sheared. Very strong flow
should be noted just off the surface but poor lapse rates and weak
buoyancy do not favor efficient mixing of stronger flow aloft to the
surface; however, gusty winds could accompany convection very early
in the period.

...Rockies/Plains...

Heights will lower considerably across the Four Corners region
during the latter half of the period as a 90kt+ 500mb speed max digs
into southeast AZ. This evolving trough should induce/maintain a
notable LLJ across the High Plains which will result in a warm front
advancing north to a position along the KS/NE border by 24/12z.
Cooling profiles and steepening lapse rates suggest some lightning
potential with the strongest convection.

..Darrow/Jirak.. 11/23/2020

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