Mesoscale Precipitation Discussion 0657
NWS Weather Prediction Center College Park MD
200 PM EDT Sat Jul 12 2025

Areas affected...Northeast PA...Central/Eastern
NY...Central/Southern VT...Western MA

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

Valid 121800Z - 130000Z

SUMMARY...Scattered slow-moving showers and thunderstorms with
heavy rainfall rates are expected going through the early evening
hours. Isolated areas of flash flooding will be possible over the
next several hours.

DISCUSSION...The latest GOES-E visible satellite imagery shows a
remnant MCV gradually drifting east across areas of central NY,
and this energy will be interacting with a very moist and unstable
airmass across the interior of the Northeast that will be
conducive for scattered areas of slow-moving showers and
thunderstorms going through the early evening hours.

MLCAPE values of 1000 to 1500+ J/kg are in place from northeast PA
through central/eastern NY and into areas of southern VT and
western MA. PWs across the region are running on the order of 1.5
to 2 standard deviations above normal, and the combination of
these two parameters should favor convective cells being capable
of producing rainfall rates of 1 to 2 inches/hour.

A combination of the aforementioned vort energy along with
localized orographic ascent near areas of higher terrain will
favor some expansion of convective activity over the next several
hours, but the convective cells will be embedded within rather
weak steering flow, and any terrain-induced circulations may tend
to favor some cells becoming orographically anchored.

This will support some localized storm total rainfall amounts
going through early this evening of 2 to 4 inches which is
supported by the 12Z HREF guidance. This will support a concern
for isolated areas of flash flooding.

Orrison

ATTN...WFO...ALY...BGM...BOX...BTV...CTP...GYX...OKX...PHI...

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

LAT...LON   44337336 44137245 43337233 42707245 42077292
            41357439 40617568 40807693 41587714 42827640
            43357537 44097422