Mesoscale Precipitation Discussion 0528
NWS Weather Prediction Center College Park MD
130 PM EDT Fri Jun 27 2025

Areas affected...Northeast OH...Northwest PA...Western Upstate
NY...

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

Valid 271730Z - 272230Z

SUMMARY...Narrow corridor of unstable air.  Multiple rounds of
efficient/intense thunderstorms may result in spots of 2-4" and
possible localized flash flooding through the evening.

DISCUSSION...GOES-E shows developing thunderstorms within a narrow
unstable axis between the colder Lower Great Lakes and a strong
differential heating boundary due to low level stratus across
central NY and PA.  Insolation has lead to temperatures reaching
the mid-80s, but return southerly flow both along the western edge
of the stratus and southwesterly upslope flow out of the Ohio
Valley continues to transport fairly moist low level moisture into
the mid-70s.  Short-wave ridge aloft is starting to shift out of
the region, though oblique right entrance ascent pattern remains
across the area to help to aid updrafts starting to develop
upstream of the mean height-falls across northern OH.  As such a
narrow axis of 1500-2000 J/kg of MLCAPEs exists along the Lakes
and will act to corral upstream development helping increase the
potential for cells to repeat/train as the main forcing presses
through this evening.

The downstream cells are likely to remain fairly stationary given
upstream propagation vectors with south/southwesterly inflow and
strong stability gradient to the east.  Total deep layer moisture
nearing 2", will support efficient rainfall and rates of
1.75-2"/hr.  Given the development environment/potential for
repeating, there is potential for some localized totals of 2-4",
which may result in possible incidents of flash flooding through
the afternoon into evening hours especially in proximity to larger
urban centers.

Gallina

ATTN...WFO...BGM...BUF...CLE...CTP...PBZ...

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

LAT...LON   43387739 42967668 42107748 41297919 40588163
            41368223 42048066 42677922 43327901