Mesoscale Precipitation Discussion 0410
NWS Weather Prediction Center College Park MD
212 PM EDT Mon Jun 09 2025

Areas affected...eastern OH/western PA/western NY

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

Valid 091810Z - 092330Z

Summary...A few areas of flash flooding will be possible from
eastern OH into western/northwestern PA and western NY through
early evening. Hourly rainfall of 1-2 inches are expected with
localized totals of 2 to 3+ inches from short term training.

Discussion...1745Z visible satellite and regional imagery showed
developing showers and thunderstorms extending from central Lake
Ontario into northwestern PA, along a pre-frontal trough axis/wind
shift. Back to the west, additional activity was forming over
central and eastern OH, just ahead of a slow moving cold front.
Area 12Z soundings and GPS PWs indicated precipitable water values
ranged from 1.2 to 1.5 inches within the warm sector from central
OH to western NY and the 17Z SPC mesoanalysis showed MLCAPE of
500-1000 J/kg from near Buffalo, NY to southern/eastern OH.

Continued surface heating through a mixture of cloud coverage 
across the region and southwesterly low level advection of
moisture will allow surface temperatures/dewpoints to come up a
bit more through peak heating supporting RAP forecasts of MLCAPE
by 21Z of 500-1500 J/kg for the MPD threat area. A mixture of
storm types will be possible given sufficient shear/instability
for organized convection but storm motions are expected to be
roughly 30-40 kt for most of the region which should keep
individual cells progressive. However, as the cold front slowly
progresses eastward, pre-frontal convergence axes and
storm-induced outflow boundaries are expected to align with the
unidirectional flow from the SW, supporting periods of training.
Hourly rainfall of 1-2 inches is expected within training and
localized 2 to 3+ inch totals will be possible through about 00Z.
Flash flood guidance is relatively low (1+ inches per 1 to 3
hours) from portions of eastern OH into a good portion of PA and
into areas of NY just north of the PA border. Exceedance of these
lower FFG values will potentially lead to a few areas of flash
flooding as storm coverage increases over the next few hours.

Otto

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

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

LAT...LON   43787671 43417592 42327661 40907872 40088075
            39748201 40238294 41298225 42437986 43407908