AWUS01 KWNH 281034
FFGMPD
NYZ000-PAZ000-OHZ000-281600-

Mesoscale Precipitation Discussion 0874
NWS Weather Prediction Center College Park MD
633 AM EDT Tue Jul 28 2026

Areas affected...western/northern PA into western/central NY

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

Valid 281032Z - 281600Z

SUMMARY...Scattered areas of flash flooding will remain possible
across portions of western/northern PA into western/central NY
through 16Z (12 PM EDT). Training of heavy rain will support
hourly totals of 1 to 2 inches (locally higher).

DISCUSSION...scattered thunderstorms were ongoing as of 1015Z
across central NY into western and northeastern PA. These storms
have had a history of generating widely scattered instances of
hourly rainfall between 1-2 inches over the past few hours but
coverage has been low so far. The storms were occurring out ahead
of a mid to upper-level shortwave trough and associated cold front
advancing SE across southern Ontario. A number of embedded
vorticity maxima were noted within the westerly to northwesterly
mid-level flow. One vorticity max in particular was observed over
northern Lake Erie, with blossoming convection just ahead of the
circulation, with additional development likely over portions of
northwestern PA and western NY within the next 1-3 hours.

Appreciable MLCAPE of 500-1000 J/kg was limited to a small region
of western NY in the vicinity of Buffalo into northeastern OH.
However, instability will expand across much of central NY into PA
this morning as daytime heating gets underway and continued
moisture advection from the southwest contributes to higher
dewpoints in the 925-850 mb layer. Additional forcing for ascent
will come as the upper trough axis over southern Ontario advances
east with increasing upper level diffluence and divergence within
the left-exit region of 90-110 kt jet streak near 200 mb advances
downstream. Individual cells are expected to track toward the east
with the deeper layer mean flow, but upstream development and repeating/training are likely to contribute to scattered areas of
training containing hourly rainfall of 1-2 inches (locally higher)
in a few locations. Resulting rainfall totals through 16Z are
expected to range from 2 to 3 inches (locally higher) with areas
of flash flooding possible, especially should there be overlap
with urban areas or otherwise poorly draining locations.

Otto

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

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

LAT...LON 43947657 43897608 43337516 42247527 41267626
40797750 40417889 40708041 41328064 42008063
42358014 42577978 42967932 43457921 43617850
43787732

$$
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