Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Jul 10 2023 11:45:31

AWUS01 KWNH 101145
FFGMPD
MAZ000-NHZ000-CTZ000-101700-

Mesoscale Precipitation Discussion 0687
NWS Weather Prediction Center College Park MD
745 AM EDT Mon Jul 10 2023

Areas affected...Southern NH...Central MA

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

Valid 101145Z - 101700Z

SUMMARY...Periods of heavy rainfall, possibly ranging between
1-1.5"/hr in the heaviest showers and storms, may cause flash
flooding this morning in urbanized communities and locations with
overly saturated soils.

DISCUSSION...The surface low in the Long Island sound features a
warm front stretching south of of the southern New England coast.
As the morning unfolds, the upper trough will develop a 500-850mb
low and continue to funnel SSE 850mb moisture flux into New
England. PWATs are generally between 1.8-1.9", values that
according to NAEFS are above the 97.5 climatological percentile at
12Z. MUCAPE is generally lacking, but values may approach 250-500
J/kg later this morning as the warm front inches north. The strong
low level SE flow is ideal for upslope enhancement into the
Worcester Hills and southern slopes of the Whites. The steady 300K
isentropic lift will foster periods of heavy rain into the
Merrimack Valley today as well. Lastly, there are also heavier
showers approaching from RI that could lead to locally heavy
rainfall in the Boston metro area.

Given the lack of instability, this should help to limit the top
end rainfall rates to be <1.5"/hr. That said, soils are still
quite saturated thanks to 300-600% of normal rainfall over the
past 7-days according to AHPS. As the 500mb trough takes on a
slight negative tilt, there could be further enhancement of the
precipitation shield into the late morning and early afternoon
hours. Given the prolonged nature of the rainfall expected, flash
flooding is possible this morning. Locations most vulnerable in
the area highlighted with the heaviest rainfall over the past
week, as well as urbanized communities and low-lying, poor
drainage spots. Possible impacts include gradually rising
streams/creeks and flooding/ponding on roadways.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6DZHQCP3F5wUwxcjQgubSqTs_n42bLDFilIrYSTu3-zFhT1ryJvC9NeGoiRwZwEOsTIJ=
7F3Qj4nf8WNNUpNJWVoV_nI$  for graphic product...

ATTN...WFO...BOX...GYX...

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

LAT...LON   43587162 43367121 42927101 42237103 42217164=20
            42027230 41997252 42217244 42557222 43047190=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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