Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat May 31 2025 09:00:39

AWUS01 KWNH 310900
FFGMPD
MAZ000-NHZ000-VTZ000-CTZ000-NYZ000-NJZ000-PAZ000-311400-

Mesoscale Precipitation Discussion 0339
NWS Weather Prediction Center College Park MD
500 AM EDT Sat May 31 2025

Areas affected...northern NJ/southern NY into central New England

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

Valid 310858Z - 311400Z

SUMMARY...The potential for localized flash flooding from an
additional 1-3 inches of rain will exist from northern NJ/southern
NY into central New England through 14Z. Peak hourly rainfall near
1 inch will be possible.

DISCUSSION...08Z surface observations showed an unusually strong
surface low for late May of 987 mb located between Somerset and
Morristown, NJ, tracking toward the northeast. Radar imagery and
surface observations showed areas of heavy rain over northeastern
PA, northern NJ and southern Upstate NY. Within this region, gauge
reported hourly rainfall has generally peaked in the 0.5 to 1.0
inch range, though it has been as high as 1.5 inches over western
Morris County, NJ ending 08Z.

Northern NJ had the highest area MLCAPE via 08Z SPC mesoanalysis
data (up to 500 J/kg), wrapping in from the western Atlantic just
north of the surface low. This region of northern NJ overlapped
with low level convergence to the northwest of the surface to 850
mb low and locally strong upper level divergence/diffluence within
the left-exit region of an upper jet streak off of the
Mid-Atlantic coast. Elsewhere, instability was limited which was
limiting rainfall rates despite the robust forcing for ascent.

Through ~14Z, the surface to 850 mb low will track into western CT
via recent RAP forecasts, which will send the comma
head/deformation axis northwest of the low into the lower Hudson
Valley and western/central New England including the Berkshires
and southern Green Mountains. While instability is forecast to
remain rather low across this region and total PW is expected to
lower a bit from present values, the similar SW to NE track and
orientation of the low level precipitation axis may allow for
additional rainfall totals of 1 to 2 inches (locally near 3
inches) through 14Z. However, this area of the Northeast has not
been as wet compared to locations farther south, so any instances
of flash flooding should be isolated in nature.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_5xn1N7D_RhtPWVLqMlLFFbCFStl7IShW7aAxF5ESSVuyHtL92ZYxD8mOQvjoZGBfbex=
s86cDFa9pvKwwRywtjPZlvM$  for graphic product...

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

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

LAT...LON   44077228 43947186 43437159 42767165 42187179=20
            41717239 41337314 40957378 40637422 40297460=20
            40527509 41447500 42227443 43097337 43747283=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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