805
AWUS01 KWNH 200821
FFGMPD
VAZ000-WVZ000-OHZ000-KYZ000-201300-

Mesoscale Precipitation Discussion 1340
NWS Weather Prediction Center College Park MD
420 AM EDT Sun Sep 20 2026

Areas affected...Southern OH...Western and Central WV

Concerning...Heavy rainfall...Flash flooding likely

Valid 200820Z - 201300Z

SUMMARY...Additional areas of flash flooding will be likely
through mid-morning from locally repeating rounds of heavy showers
and thunderstorms.

DISCUSSION...The latest GOES-E IR satellite imagery along with
radar data shows multiple rounds of heavy showers and
thunderstorms locally repeating over the same area across portions
of southern OH and into western and central WV. Separate
convective activity more recently has developed across portions of
southwest PA as well. All of this activity is being facilitated by
the advance of surface low pressure up across northeast OH and
warm air advection lifting up across the Upper OH Valley and the
central Appalachians.

Modest low-amplitude shortwave energy transiting the region is
also still interacting with modest instability characterized by
MUCAPE values of 500 to 1000 J/kg, with the greatest instability
generally down across northeast KY, far southeast OH and into
central and southern WV. Some stronger updrafts and occasional
overshooting top activity is seen in the IR satellite images
advancing into western WV, and some of these stronger convective
cells are still capable of producing 1 to 2 inch/hour rainfall
rates, and especially with a moist column characterized by PWs
locally near 2 inches.

The latest HRRR guidance suggests additional concerns for
repeating rounds of convection going through the early to
mid-morning hours. Some additional rainfall totals may locally
reach 2 to 3+ inches given the higher rainfall rates with some of
the stronger storms. It should be noted that some hires guidance
does suggest some potential for convection to redevelop by
mid-morning farther back to the northwest across south-central OH
in connection to the advance of the upstream Midwest convective
activity and related downstream warm air advection, so this will
needy to be closely monitored.

Given areas of ongoing flash flooding, the low FFG values more
regionally across the region, and the generally elevated
streamflows, these repeating rounds of heavy rainfall are likely
to result in additional areas of flash flooding this morning. The
greatest potential for this will mainly be across far southern OH
through central WV which is where the overall heaviest axis of
rainfall is expected over the next several hours.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

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

ATTN...RFC...RHA...TIR...NWC...

LAT...LON   40018206 39698041 39087934 38527943 38157991
            37908054 37898135 38078209 38448284 39028435
            39648430 39888375