Mesoscale Precipitation Discussion 0221
NWS Weather Prediction Center College Park MD
738 PM EDT Sun May 04 2025

Areas affected...Portions of Northern WV...Western PA...Far
Northeast OH

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

Valid 042337Z - 050437Z

SUMMARY...A couple of bands of slow-moving, but heavy showers and
thunderstorms may result in a few localized areas of flash
flooding through the early to mid-evening hours.

DISCUSSION...The latest radar imagery shows a couple of bands of
heavier showers and thunderstorms materializing across northern WV
and western PA as a pool of late-day instability remains focused
near a very slow-moving frontal occlusion. This is all associated
with the deep layer cyclone pivoting slowly across the OH Valley.

RAP data shows a corridor of favorable low-level moisture
convergence along the frontal occlusion coinciding with as much as
1000 J/kg of MLCAPE. Relatively divergent flow aloft around the
northeast quadrant of the deep layer trough/closed low over the OH
Valley is also yielding at least some modest deep layer ascent.

GOES-E IR satellite data has been showing some additional
convective cloud top cooling over the last 30 to 45 minutes and
this has been coinciding with MRMS data showing some increase in
rainfall rates, with some of the stronger storms yielding rates up
to close to 1 inch/hour.

Over the next few hours, expect a couple of relatively slow-moving
bands of convection to continue to pivot across portions of
northern WV, western PA and possibly getting into far northeast OH
with at least some brief cell-training concerns that could yield
rainfall totals upwards 1.5 to 2.5 inches. This may be enough to
exceed the 1-hour and 3-hour FFG values locally. Therefore, a few
localized areas of runoff problems and flash flooding will be
possible.

Orrison

ATTN...WFO...CLE...CTP...LWX...PBZ...RLX...

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

LAT...LON   41938036 41567967 40667912 39277940 38837986
            38948031 39348035 40188042 40988069 41468110
            41908097