Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Jul 29 2023 22:30:07

AWUS01 KWNH 292230
FFGMPD
MEZ000-MAZ000-NHZ000-RIZ000-VTZ000-CTZ000-NYZ000-NJZ000-300328-

Mesoscale Precipitation Discussion 0815
NWS Weather Prediction Center College Park MD
629 PM EDT Sat Jul 29 2023

Areas affected...portions of southeast NY & southern /coastal New
England

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

Valid 292228Z - 300328Z

Summary...Thunderstorms continue to increase in coverage and train
across the region.  Hourly rain totals to 2.5" and local amounts
to 4" are possible, which keeps flash flooding likely.

Discussion...An incoming MCV and surface wave are acting to hold
up the southern progression of training thunderstorms to their
east across portions of southern NY, southern New England, and
portions of coastal ME.  Precipitable water values of 1.7-2.2" lie
across the region per GPS data, which is exceptionally high for
the region.  Effective bulk shear of 30-50 kts along with
unidirectional west-southwest flow is helping to form the training
bands.  ML/MU CAPE of 250-2000 J/kg lie across the region, with
lowest amounts near the ME coast behind the slowly progressive
cold front.  Radar estimates of hourly rainfall have approached
2.5", which befits the amount of moisture and instability
available.

The 18z HREF indicates that there is over a 50% chance of 3"
totals over the next six hours...4" is a reasonable estimate for
additional rainfall totals.  See no reason why hourly totals to
2.5" could not be realized before this activity sweeps out to sea
by 04z.  Portions of the region have been wet this past week,
particularly near the border of MA/CT and a small area of southern
ME.  Flash flood guidance values are modest enough that hourly
rain totals could occasionally breach the 3 hourly guidance.=20
Hence, flash flooding remains likely.

Roth

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!4pQgYis8o5pC_-W6a3NeMhNcvCn2BwXmep0WGHD0Xb2qs5VFN83hQtsmONIuBcPLV0QV=
84ba3y7AQeFRRcKcbi0rtxE$  for graphic product...

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

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

LAT...LON   44516810 44246798 43367011 42207060 41497217=20
            41217462 42337434 42727276 44327074=20

=3D =3D =3D
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