Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Jul 16 2024 18:50:56

AWUS01 KWNH 161850
FFGMPD
NHZ000-VTZ000-NYZ000-PAZ000-170000-

Mesoscale Precipitation Discussion 0631
NWS Weather Prediction Center College Park MD
250 PM EDT Tue Jul 16 2024

Areas affected...Portions of the Interior Northeast...New England

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

Valid 161849Z - 170000Z

Summary...Convection across western New York is intensifying and
expanding ahead of an MCV and associated surface low. Efficient
warm rainfall production with this activity could lead to hourly
rainfall rates of 2-2.5"/hr, which could cause a few instances of
flash flooding in spite of generally progressive storm motions.

Discussion...Recent radar and IR imagery show an intensifying
convective complex across western New York as a well defined MCV
migrates eastward. Single source and MRMS hourly rainfall
estimates within the most intense activity 2"/hr rainfall rates
noted downwind of Lake Ontario. While bowing segments within this
complex resulted in quick forward propagation of 30-40 kts,
scattered CREST Unit Streamflows of 200-300 cfs/smi were noted in
the wake of this activity owing to the high rainfall rates.=20

The most intense rainfall rates are occurring within a notable
PWAT max (1.8-2" per TPW and objective analysis estimates) which
overlap with a highly sheared and unstable airmass (50 kts 0-6 km
shear and 1500-2000 J/kg MLCAPE) immediately downstream of the
MCV. Ahead of the MCV, TPW shows widespread moistening downstream
of the ongoing activity. With RAP point soundings showing warm
cloud depths of 12-14,000 feet in the inflow region of these
storms, efficient rainfall rates of 2-2.5"/hr are expected within
the most intense cells this afternoon.

While the fast storm motions and generally dry antecedent
conditions preclude a more robust flash flood threat, 1-3 HR FFGs
across portions of the region are fairly low (varying from
1-2.5"). Given the potential for high rainfall rates, HREF
neighborhood probabilities show high chances (40-60%) of 1-3 HR
FFG exceedence through the afternoon. This suggests a few
instances of flash flooding are possible as this activity
continues, with areal rainfall totals of 2-3" possible through 0Z.

Asherman

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7Rb-J0B0WvIG1RTH45rpMnyXwgApHRnrAKR7IuHIQLCmdoZz1hAeJqlX0Lql2wZX8fes=
SN15tNuudffQT4BGTFdJIJQ$  for graphic product...

ATTN...WFO...ALY...BGM...BTV...BUF...GYX...

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

LAT...LON   45157309 44687206 43577229 43037329 42907477=20
            41927628 42577668 43757653 44497592 45087508=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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