Mesoscale Precipitation Discussion 0399
NWS Weather Prediction Center College Park MD
454 AM EDT Sun Jun 08 2025

Areas affected...Southern OH...West Virginia...Northwest
VA...Western MD...Adj Southwest PA...

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

Valid 080900Z - 081500Z

SUMMARY...Slow moving, warm cloud heavy showers capable of
1-1.5"/hr and locally 2"+ across complex terrain (or stationary
near old upper low).  Isolated flash flooding remains possible
through daybreak.

DISCUSSION...GOES-E WV suite depicts shortwave continuing to pivot
and slowly shift eastward into west-central Ohio, while westerly
flow continues to under-cut the shearing trough axis toward a new
cyclonic rotor across southwest VA.  As such, remaining slug of
enhanced moisture continues to be advected upslope across E OH/WV
wringing out the remaining 1.5-1.7" total PWats remaining in the
western branch of the warm conveyor belt back to the old shearing
out shortwave.  Remaining pockets of 500-750 J/kg of CAPE will
help to maintain a few localized stronger updrafts within the
larger shield precipitation.  Cores will continue to be relatively
narrow but even shallow in nature will still have the capability
of efficient warm cloud processes with rates/totals of 1-1.5"
possible.  Given the narrow gullies/terrain channels, this may
result in localized flash flooding incidents across WV slowly
shifting into W PA/W MD after 13-15z. 

Further west (Western and Central Ohio), near the inner core of
the shortwave, strong directional convergence near the center may
result in similar 1-1.5"/hr rates and spotty totals of 2"+ in a
SHaRS (Subtle Heavy Rain Signature) type event due to near
stationary cell motions.  This is more likely over the next 1-3
hours before the warm conveyor belt is severed by active
convection downstream toward the new developing shortwave in the
Mid-Atlantic. 

Shenandoah/Blue Ridge...
WV suite shows solid anticyclonic shield with transverse banding
features typical of right entrance ascent in proximity of central
VA as the developing shortwave starts to stretch east of the
Appalachians in the next few hours.  Still with upstream shortwave
energy and surface front banked up west of the ridge, surface to
boundary layer winds will respond by backing and increasing toward
20kts in the next few hours.  Convection is already starting to
develop across the Piedmont in response to the deep layer WAA, but
winds banking in easterly upslope will take a few more hours to
respond.  However, as they do, they will be generally orthogonal
with solid 1.5-1.75" TPW moisture flux into developing cells along
the ridges tapping into weak unstable environment.  Rates of
1-1.5"/hr will be common here as well, but may see
upstream/back-building cells for a few short-term repeating
elements.  Localized totals nearing 2" may result in focused
incident or two of flash flooding especially given FFG values
remain reduced across the area ranging from .75-1.5" over NW VA/E
WV Panhandle and parts of W MD. 

In all three locations, flash flooding is not likely to be
wide-spread nor with extreme totals over 2.5", however, given
complexity of the terrain and a wet spring in most locations flash
flooding is considered possible and scattered in nature.

Gallina

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

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

LAT...LON   40428421 40348337 40168215 40197979 39647943
            39657824 39167776 38047849 37767884 37587980
            37618091 38268207 39138325 39648460 40168461