Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Jul 22 2024 18:29:56

AWUS01 KWNH 221829
FFGMPD
MAZ000-CTZ000-NYZ000-NJZ000-PAZ000-222247-

Mesoscale Precipitation Discussion 0694
NWS Weather Prediction Center College Park MD
229 PM EDT Mon Jul 22 2024

Areas affected...Northern NJ...Southern Upstate NY...Northern &
Northeast PA...

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

Valid 221830Z - 222247Z

SUMMARY...Overlap of insolation and gradient of deepening moisture
has become unstable, moist enough to generate scattered
thunderstorms capable of 1.5"/hr rates and potential for cell
mergers/repeating that may allow for widely scattered 2-3" totals
and possible localized flash flooding through evening.

DISCUSSION...Broad right ascent region of strengthening 90-100 kt
3H jet and mid-level west to east trough and enhanced DPVA
crossing out of PA is providing sizable large scale ascent
along/north of the main surge of deeper tropical moisture.  Warm
front is slowly lifting through the Poconos toward Long Island
where 70+F Tds are lifting north, but isentropic/slant-wise ascent
through depth is providing solid low to mid-level moistening in
advance of the front.  Solid to loosely filtered insolation
through downstream increasing cirrus has been sufficient to warm
surface into low-mid 80s with average 60s surface Tds to support a
sufficiently unstable environment to generate stronger updrafts
downstream of stronger more tropical showers across the
Mid-Atlantic.   Total PWats are increasing at leading nose of
15-20kts 850mb flow providing solid moisture flux to support
1.5"/hr rates.

Stronger shortwave back in E PA and short-wave ridging across the
area has resulted in changing (SSW to WSW) becoming increasingly
convergent steering flow across the NY/PA line, though cells in N
NJ still remain more south to north.  Overall, this may allow for
cell mergers or repeat cells given upstream development and
tracking through of cells currently across SE PA (see MPD 692 for
more details).  As such, spots of 2-3" are possible through the
late afternoon into evening into an increasingly less favorable
ground condition, with hourly FFG values of 1-2"/hr and <2.5"/3hr.
 Given rates or spotty totals up to those values; widely scattered
incidents of flash flooding are possible (particularly in urban
centers with hydrophobic ground types)

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!9sT5oPpUh62wNC4GLGAFaFqv0jzuW9CubeXa7gCAtwb21WFEeK5huoNlo-yFG8D2RC4s=
2B0K88ilqv_X3kWKCPpGW1g$  for graphic product...

ATTN...WFO...ALY...BGM...CTP...OKX...PHI...

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

LAT...LON   43197526 43157422 42687347 42117325 41077369=20
            40237461 40267504 40637539 41047575 41677719=20
            42447718 42987647=20

=3D =3D =3D
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