Mesoscale Precipitation Discussion 0570
NWS Weather Prediction Center College Park MD
644 PM EDT Tue Jul 01 2025

Areas affected...Portions of the Mid-Atlantic and Northeast

Concerning...Heavy rainfall...Flash flooding likely

Valid 012244Z - 020444Z

Summary...Flash flooding threat will continue through the evening
hours as cells containing 2-3"/hr rainfall rates at times train
and repeat.

Discussion...Radar depicts widespread thunderstorm coverage across
the Mid-Atlantic and Northeast ahead of an approaching shortwave
trough and associated cold front. Throughout the afternoon,
training and repeating of these storms along a northeast-southwest
axis led to prolific heavy rainfall across the region, with
numerous instances of flash flooding reported.

Over the last several hours, the most intense cells have
propagated southeastward into the instability axis, characterized
by 2000-3000 J/kg of MLCAPE and 2-2.3" PWATs according to
objective analysis output. This regime should continue through the
evening hours, with periods of cell training expected as the
steering flow remains quasi-parallel to the synoptic forcing and
leading composite outflow. The approaching shortwave trough and
strengthening right-entrance region ascent this evening should
also favor expanding convective coverage over the next several
hours. Recent runs of both the HRRR and RRFS consistently depict
swaths of 2-4" through 4-5Z across the highlighted region where
cells can train the longest. This should maintain the threat of
flash flooding through the evening hours -- some of which could be
significant if it can overlap with hard hit areas.

Asherman

ATTN...WFO...AKQ...GSP...LWX...MRX...PHI...RAH...RNK...

ATTN...RFC...ALR...ORN...RHA...TIR...NWC...

LAT...LON   40087395 39467375 38147530 37367678 36857781
            36097948 35118126 35248209 36378183 37897973
            38707704 39807495