Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Jun 26 2023 00:57:51

AWUS01 KWNH 260057
FFGMPD
MEZ000-MAZ000-NHZ000-VTZ000-NYZ000-260600-

Mesoscale Precipitation Discussion 0582
NWS Weather Prediction Center College Park MD
857 PM EDT Sun Jun 25 2023

Areas affected...northern NY into VT/NH/western ME

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

Valid 260055Z - 260600Z

Summary...Localized spots across northern NY into New England may
see a quick 2-4 inches of rain over the next few hours. This will
continue the flash flood risk through ~06Z.

Discussion...Infrared and Fading visible satellite imagery at
0020Z showed widely scattered shower and thunderstorm activity
from portions of central and northern NY eastward into New
England. New development continued in a few locations partially as
a result of the movement of numerous outflow boundaries within a
fairly moist (PWs 1.6 to 1.8 inches) and weakly unstable
environment (MLCAPE of 500-1000 J/kg via 00Z SPC mesoanalysis).
Weak deep-layer mean flow and similarly oriented 850 mb winds have
allowed for the slow movement of individual cells with a history
of high rainfall rates with observed values of 0.5 to 1 inch in 15
minutes and 2+ in/hr over the past few hours.

Despite the loss of daytime heating, convective inhibition is
expected to be slow to increase over northern NY into New England
due to high surface dewpoints in the upper 60s to lower 70s and
minimal dry air in the column as sampled by the 00Z GYX sounding.
The combination of the nocturnal diurnal cycle and an approaching
upper level low currently over NJ should act to minimally increase
850 mb winds from the south into New England. This subtle increase
in the low level flow will act to increase thunderstorm coverage
and as low level winds approach the deeper layer steering flow,
the potential for short term training and overall slow movement of
cells will amplify, with a quick 2-4 inches possible on a very
localized basis.

While antecedent conditions continue to be dry for many areas of
the region, some locations have picked up locally heavy rain over
the past few days, which may increase susceptibility to flash
flooding if overlap occurs with additional heavy rain overnight.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-u9ecoe_dNYV0YAr6w2lNzsrLNiwH2Vf7efGnThWxHjHzY0ROvhJkiS0qUg1iHF37gvB=
Py_4NzB9MAFps09H1duclyM$  for graphic product...

ATTN...WFO...ALY...BGM...BOX...BTV...BUF...GYX...

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

LAT...LON   45067054 44607041 43807067 43267124 42757258=20
            42647408 42827510 43677579 44547515 44607390=20
            44707290 44977157=20

=3D =3D =3D
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