AWUS01 KWNH 041839
FFGMPD
MEZ000-NHZ000-VTZ000-NYZ000-050037-

Mesoscale Precipitation Discussion 0804
NWS Weather Prediction Center College Park MD
238 PM EDT Sun Aug 04 2024

Areas affected...northeastern New York state, northern Vermont,
northern New Hampshire, and portions of Maine

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

Valid 041837Z - 050037Z

Summary...Scattered thunderstorms are producing brief heavy
rainfall and areas of 1-1.5 inch/hr rain rates at times.  These
rates are falling on sensitive ground conditions and are likely to
result in instances of flash flooding through the early evening.

Discussion...Scattered thunderstorms have developed across the
discussion area amid a destabilizing airmass (characterized by
2000-2500 J/kg MLCAPE) and weak forcing for ascent aloft
associated mid-level waves over New York.  The storms are embedded
in appreciably high PW air (characterized by 1.5 inch PW values)
and only modest westerly steering flow aloft, supporting slow
storm motions (around 10-20 knots).  These cores were falling on
locally sensitive ground conditions from prior rainfall over the
past week (particularly near St. Johnsbury and vicinity), and FFG
thresholds (generally in the 1-1.5 inch/hr range) were being
locally exceeded as slow-moving thunderstorms were progressing
through the region.

Much of the flash flood threat across the region should be
diurnally driven, although a lingering threat after dark should
exist with any persistent cells or clusters.  Some of the ongoing
convection should gradually merge/grow upscale into
forward-propagating clusters, although the process of
merging/localized training could further bump rain rates into the
1.5-2 inch/hr range at times.  Flash flood potential is likely to
persist through at least 23Z this evening.

Cook


ATTN...WFO...ALY...BTV...CAR...GYX...

ATTN...RFC...NERFC...NWC...

LAT...LON   46726886 46546812 45916789 45266826 44696958 
            43937245 43717431 44387477 44927436 45017357 
            45177239 45527127 46007044 46526986 
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