SPC 2000Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0254 PM CDT Mon Sep 28 2020

Valid 282000Z - 291200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
OF THE GULF COAST STATES INTO THE OHIO VALLEY...

...SUMMARY...
Isolated strong wind gusts remain possible this afternoon into the
early evening from a portion of the Gulf coastal states into Ohio.

...Gulf coastal states through eastern Ohio...

Recent radar trends show an increase in thunderstorm intensity along
a portion of the front primarily from the Gulf coastal states into
middle Tennessee where instability is a bit stronger than farther
north across the OH Valley. Destabilization of the surface layer has
occurred in pre-frontal warm sector, and vertical wind profiles in
vicinity of the cold front are marginally sufficient for storm
organization over the Gulf Coast states. Farther north into the OH
Valley, wind profiles are more favorable for organized storms, but
the thermodynamic environment is very marginal and will remain a
limiting factor. Will maintain MRGL risk category for this update
with primary threat being isolated strong wind gusts. See SWOMCD
1722 for more information.

..Dial.. 09/28/2020

.PREV DISCUSSION... /ISSUED 1127 AM CDT Mon Sep 28 2020/

...OH to the central Gulf coast...
Within a large-scale trough over the Great Plains/MS Valley, an
initial mid-upper speed max will rotate north-northeast from IL/IN
into southern Ontario. Pronounced cyclogenesis is expected through
tonight from the Lake Huron vicinity north towards James Bay. The
trailing cold front will continue to move east across the OH Valley
to central Gulf Coast regions. Poor mid-level lapse rates are
expected within the majority of the warm sector, and the richer
low-level moisture (boundary-layer dewpoints in the low-mid 70s)
will be confined to the Gulf Coast. Thus, buoyancy will be rather
shallow and limited in magnitude to the north in the OH Valley
(MLCAPE 
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