Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Jul 10 2023 08:13:27

AWUS01 KWNH 100813
FFGMPD
MAZ000-RIZ000-CTZ000-NYZ000-101400-

Mesoscale Precipitation Discussion 0685
NWS Weather Prediction Center College Park MD
412 AM EDT Mon Jul 10 2023

Areas affected...Eastern Long Island...Southern New England...

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

Valid 100815Z - 101400Z

SUMMARY...Very strong sfc moisture flux convergence will drive
very efficient warm cloud rainfall along/near Coastal New England
and Eastern Long Island through morning.=20

DISCUSSION...Broader surface low in the New York Bight as been
slow to organize, but a small but potent cluster of showers and
thunderstorms has resulted in isallobaric wind flow response as it
has lifted through central Long Island.  Stronger 20-25kts of sfc
to boundary layer flow, per OKX VWP combined with 1500 J/kg of
SBCAPE and near 2" total PWat values have supported rates up to
3"+/hr.  There has been a bit of down trending recently, but as
the surface low slowly drifts ENE, strong moisture convergence and
available surface based instability will support further
convective development along and downstream across E LI, E CT into
RI/S MA through the early morning hours.=20=20

Upper-level shortwave starting to stall/pivot acros central
upstate NY will allow for mid-level negative trof axis to align
favorably across the New York Bight for favorable mid to upper
level ascent dynamics for potential upstream redevelopment and
repeating cells across the area as well.  Uncertainty still exists
with forward propagation of the surface low and therefor best
moisture convergence.  Slower progression will allow for increased
totals over E CT/E LI with 3-5" possible. However, if more
progressive, thunderstorms will likely be more oriented closer to
the coast with less northward training/ repeating...reaching SE MA
by 15z, this will allow for more spotty 2-4" totals.  Either
scenario is likely to induce localized flash flooding... though
certain locations (E LI/SE MA) with sandier soils and recent
dryness would be less susceptible unless magnitudes are much
higher than urban areas of central CT or RI.  All considered, the
potential rises to a level to consider flash flooding or rapid
inundation flooding as likely this morning.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7qSKBBOIf3zGrxZvWXCYpuM9cEEDOvlfx581UPj2W54z-T3hArWkcExBhZwuD8vPYOoc=
QXIYbk5oh-eOuVm7WEH9W18$  for graphic product...

ATTN...WFO...BOX...OKX...

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

LAT...LON   42187113 41937055 41637041 41287053 41167115=20
            40947185 40807220 40567332 41427304 41947249=20
            42177179=20

=3D =3D =3D
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