Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Aug 25 2023 08:42:29

AWUS01 KWNH 250842
FFGMPD
VAZ000-WVZ000-OHZ000-251240-

Mesoscale Precipitation Discussion 0974
NWS Weather Prediction Center College Park MD
441 AM EDT Fri Aug 25 2023

Areas affected...Southeast OH...Northern/Central WV

Concerning...Heavy rainfall...Flash flooding possible

Valid 250840Z - 251240Z

SUMMARY...Localized training of heavy showers and thunderstorms
over the next few hours may result in a few instances of flash
flooding.

DISCUSSION...The latest radar imagery shows a broken axis of heavy
showers and thunderstorms dropping southeast across areas of
southeast OH and through northern WV. Over the last hour, some of
this activity has become better aligned with the deeper layer flow
in a northwest to southeast fashion which has begun to favor at
least some training of these cells.

Over the next 2 to 3 hours, this convection will likely tend to be
sustainable given the level of instability still pooled across the
OH Valley and toward the western slopes of the central
Appalachians along with favorable moisture convergence in vicinity
of the convectively driven outflow boundary.

MLCAPE values across areas of southern OH and western WV are on
the order of 1500 to 2500+ J/kg with the convection generally
traversing a well-defined instability gradient just off to the
east and north. There is an axis of fairly strong effective bulk
shear coinciding with this instability gradient and ongoing
convective axis, and so the convection may still tend to hang onto
some loose organization going through the dawn time frame.

PWs are upwards of 1.75 inches, and this moist airmass coupled
with the instability will favor some of the stronger convective
cells producing rainfall rates that may reach upwards of 2
inches/hour.

Given some of the concerns for some cell-training in the
short-term, there may be a few instances of flash flooding that
materialize. FFG values across southeast OH and northern/central
WV are relatively low, and with the HRRR guidance supporting some
spotty 2 to 3 inch amounts over the next few hours, some runoff
problems will be possible.

Orrison

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!9f97QVMILlCEC_3VcIygmsDGBme81OVXtj91XzUDtsdjJQ_WhRapCsbhUOLzp32zjneV=
0_SDFAtzHBx9_3rlelYp3aE$  for graphic product...

ATTN...WFO...ILN...LWX...PBZ...RLX...RNK...

ATTN...RFC...MARFC...OHRFC...NWC...

LAT...LON   40138164 39688101 39067949 38497942 38178048=20
            38878207 39668270 40048254=20

=3D =3D =3D
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