Mesoscale Precipitation Discussion 1338
NWS Weather Prediction Center College Park MD
1147 PM EDT Sat Sep 19 2026

Areas affected...Southern OH...Western WV

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

Valid 200347Z - 200930Z

SUMMARY...Isolated areas of flash flooding will be possible as
some uptick in shower and thunderstorm activity occurs over the
next several hours.

DISCUSSION...The latest GOES-E IR satellite imagery along with
radar data shows some development and expansion of shower and
thunderstorm activity taking place across portions of southern OH.
This activity is occurring as warm air advection increases out
ahead of a couple of weak waves of low pressure advancing east
along frontal zone.

Modest low-amplitude shortwave energy transiting the OH Valley is
also playing a role with some of the convective development as it
interacts with moderate instability characterized by MUCAPE values
of 1500 to 2000+ J/kg. The airmass is quite moist with PWs of 1.75
to 2.0 inches, and this will be supporting convective cells
capable of producing rainfall rates of 1 to 2 inches/hour.

The 00Z HREF guidance and recent HRRR runs suggest some additional
expansion of showers and thunderstorms over the next few hours
across southern OH, and the activity will likely advance
downstream into western WV later in the night. Some cell-training
is possible given the alignment of the convection with the deeper
layer steering flow.

Localized rainfall totals of 2 to 4 inches will be possible, and
this may support some isolated areas of flash flooding.

Orrison

ATTN...WFO...ILN...PBZ...RLX...

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

LAT...LON 40258350 40118231 39828104 39348017 38678020
38398098 38468205 38748331 39208435 39738466
40128428