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SPC Oct 25, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0300 PM CDT Mon Oct 25 2021

Valid 252000Z - 261200Z


Threat for mainly a few strong to damaging wind gusts and possibly a
tornado or two exists this afternoon and evening from central North
Carolina into Virginia.


Only modest adjustments have been made to previous outlook,
primarily to trim on western end of SLGT to reflect current trends.
See swomcd 1899 for more information.

..Dial.. 10/25/2021

.PREV DISCUSSION... /ISSUED 1127 AM CDT Mon Oct 25 2021/

...Eastern KY/OH to NC/VA this afternoon/evening...
A midlevel shortwave trough over IN/KY/TN this morning will progress
eastward to the Appalachians this evening and VA/NC overnight.  An
associated surface cyclone will move eastward from northeast IN
across northern OH today while slowly weakening, and a trailing cold
front will likewise move eastward across TN/KY/WV/OH through this
evening.  A band of convection will be possible along the cold front
this afternoon in conjunction with a narrow zone of cloud
breaks/surface heating and modest low-level moisture (surface
dewpoints of 56-60 F) across OH/KY.  Buoyancy will remain weak
(MLCAPE < 500 J/kg) and wind profiles will be only modestly
favorable for organized severe storms (effective bulk shear near 30
kt) suggest that any severe threat with to storms along the cold
front should remain marginal.

Farther east, low-level moisture is increasing from eastern NC into
VA, on the west side of a separate shortwave trough ejecting
northeastward near the southeast Atlantic coast.  The moisture
should be able to spread far enough west and north to support
thunderstorm development later this afternoon near the Blue Ridge,
as the primary cloud/ascent band (now across eastern KY into WV)
reaches the west edge of the richer low-level moisture.  Wind
profiles will be sufficient for supercells with effective bulk shear
of 40-50 kt, given MLCAPE up to 1000 J/kg.  Occasional damaging
gusts will be the main concern, though a tornado or two may also
occur near the NC/VA border where effective SRH of 100-150 m2/s2 is
expected by late afternoon.  Otherwise, convection is expected to
grow upscale into clusters/line segments, with an attendant threat
for damaging winds through late evening.

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