Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Jul 08 2023 15:46:25

AWUS01 KWNH 081546
FFGMPD
MEZ000-MAZ000-NHZ000-VTZ000-CTZ000-NYZ000-082145-

Mesoscale Precipitation Discussion 0662
NWS Weather Prediction Center College Park MD
1144 AM EDT Sat Jul 08 2023

Areas affected...New England

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

Valid 081545Z - 082145Z

SUMMARY...Slow moving storms may produce >2"/hr rainfall rates
this afternoon. Flash flooding is possible with areas featuring
the most saturated soils most vulnerable.

DISCUSSION...This morning's surface analysis showed a stationary
front oriented N-S from western VT into the Hudson Valley and all
the way into the northern Mid-Atlantic. There is also an elongated
surface trough located in the heart of New England. GOES-16
visible satellite imagery shows that cumulus are wasting no time
in forming along the higher terrain. Dew points are in the upper
60s and surface based heating has already led to MLCAPE increases
on the order of 400-600 J/kg over the past 3 hours. The 12Z
sounding out of Caribou, ME is a good proxy for the region as
given its minuscule CIN in place and low-mid level RH values
averaging close to 80%. RAP guidance shows PWs will range between
1.25-1.50", MLCAPE of roughly 1,000-1,500 J/kg, and warm cloud
layers could approach 10,000ft deep early-mid afternoon.

The setup is not as ripe for flash flooding as yesterday thanks to
less synoptic-scale forcing and atmospheric moisture content at
the atmosphere's disposal. The latter is evident in the 12Z
Caribou sounding, which suggests the entrainment of dry air should
help limit storm coverage to be more "hit-or-miss". That said, the
surface features mentioned and differential heating will suffice
to trigger more storms this afternoon. Mean sfc-6km winds will
generally be less than 10 knots, allowing storms to move slowly
and potentially lead to hourly rainfall rates >2"/hr. It is
possible some cells even produce as much as 2" in as little as 30
minutes in the most intense activity. Storms will not be as
organized as yesterday given less wind shear aloft, so storms will
behave more pulse-like in nature. Still, soils have grown only
more sensitive throughout the region after an active day on
Friday. AHPS shows rainfall totals from the Catskills and Hudson
Valley to central ME that have ranged between 300-400% of normal.
1-hr FFGs are <1.5" for areas hit hardest from yesterday's
rainfall. Flash flooding is possible once again today with areas
featuring highly sensitive soils in New England most at-risk.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6hxlYXbq8jEoB-6xox4Jrm68GQFkifNm3RM76w9SEmgkmQlSTqsTs-XFTvL_ar2ijUEs=
z8HGpbnXaUnxKUo-if4bW4Q$  for graphic product...

ATTN...WFO...ALY...BOX...BTV...CAR...GYX...

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

LAT...LON   47446862 46926773 45816831 44397048 43287167=20
            42437222 41937338 41997407 42617416 43427389=20
            44937351 45357117 47256957=20

=3D =3D =3D
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