883
ACUS11 KWNS 211838
SWOMCD
SPC MCD 211837
PAZ000-NYZ000-MDZ000-VAZ000-WVZ000-OHZ000-212100-

Mesoscale Discussion 2095
NWS Storm Prediction Center Norman OK
0137 PM CDT Sat Sep 21 2024

Areas affected...western New York...western
Pennsylvania...southeastern Ohio...much of West Virginia...western
Virginia...and the western Maryland Panhandle

Concerning...Severe potential...Watch unlikely

Valid 211837Z - 212100Z

Probability of Watch Issuance...20 percent

SUMMARY...A few strong thunderstorms briefly reaching marginal
severe levels can be expected through this afternoon.  Marginal hail
and tree damage can be expected locally.  However, the very
isolated/marginal nature of the risk currently expected should
preclude the need for WW consideration.

DISCUSSION...A weak cool front will continue moving southeastward
across the Mid and Upper Ohio Valley area and into the central
Appalachians today, as a vort max near Lake Huron shifts across the
Lower Great Lakes toward the Chesapeake Bay area this afternoon and
tonight.

Ahead of the front, a modestly moist boundary layer (low 60s
dewpoints) combined with warm-sector heating is resulting in around
1000 J/kg mixed-layer CAPE across much of the area, though into the
1500 to 2000 J/kg range over the middle Ohio Valley portion of the
region.  This destabilization is fueling a gradual increase in
convective coverage and intensity near and ahead of the front --
from southeastern Ohio to southwestern New York.

Though low-level flow remains weak, moderate mid-level
northwesterlies are contributing to an environment amply sheared to
support organized updrafts.  As such, locally strong/briefly
vigorous updrafts will likely be associated with marginal severe
potential into early evening -- with risk spreading gradually
eastward/southeastward with time.

..Goss/Guyer.. 09/21/2024

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...BGM...BUF...CTP...LWX...RNK...PBZ...RLX...

LAT...LON   39598204 39888105 40368027 40797954 41487892 42507897
            42717843 42207672 41327693 38777771 37647890 37308026
            38618177 39598204