Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Oct 07 2023 09:45:42

AWUS01 KWNH 070945
FFGMPD
CTZ000-NYZ000-NJZ000-071344-

Mesoscale Precipitation Discussion 1136
NWS Weather Prediction Center College Park MD
545 AM EDT Sat Oct 07 2023

Areas affected...Portions of northern New Jersey and southern New
York

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

Valid 070944Z - 071344Z

Summary...Increasing coverage of heavy showers and isolated
thunderstorms this morning may produce intense rain rates and
localized rain totals of 2-3". This may result in flash flooding
for urban and poor drainage locations.

Discussion...Ahead of an approaching cold front and upper trough,
very moist southeasterly flow interacting with weak to moderate
low level convergence near a surface trough will lead to an
increasing coverage of heavy showers and isolated thunderstorms
this morning across the outlook area. Recent blended TPW product
shows precipitable water values above 1.5" from portions of
central New Jersey through southwest Connecticut including the
southern portions of New York State. Weak to moderate low level
convergence along a pre-frontal trough and a bubble of 500+ J/kg
of SBCAPE (per recent SPC mesoanalysis) is helping to increase
shower activity per radar imagery this morning. The expectation is
that as the front approaches over the next several hours, there
should be an uptick in the shower/thunderstorm activity,
particularly across far southern New York northward through
portions of the lower/middle Hudson Valley.

The hi-res guidance has struggled with the ongoing activity since
late last evening and overall the guidance has shown more spread
than compared to yesterday. However, recent runs of the HRRR and
the 06Z HREF probabilities still suggest the potential for
localized hourly rain totals over 1", in/near some of the most
saturated soil areas due to recent heavy rain (portions of
northern NJ and southern NY) and through mid-morning, neighborhood
probabilities of 3" totals remain above 60 percent with a slight
signal for 3-5". Given that this rainfall would be near/over very
saturated soils with low FFG values (1-hr values under 1" in some
spots), should heavy shower/thunderstorm activity materialize,
localized flash flooding will be possible, particularly for urban
and poor drainage locations.

Taylor

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-hoGR5IwVbj80SofNDZv27_noke6vHOtO3KFi1_eHzfPjzMfSJsXlr5zE9c2LgEkrz2R=
UzYM0i6MtQkhzNRNQH_dnxs$  for graphic product...

ATTN...WFO...ALY...OKX...PHI...

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

LAT...LON   41567418 41517390 41297370 41027371 40497370=20
            40117369 39977379 39897404 40097442 40437460=20
            40777472 41147462 41497431=20

=3D =3D =3D
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