440
AWUS01 KWNH 141926
FFGMPD
MAZ000-CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-150125-

Mesoscale Precipitation Discussion 0437
NWS Weather Prediction Center College Park MD
325 PM EDT Fri Jun 14 2024

Areas affected...Portions of the Northern Mid-Atlantic...Southeast
NY...Far Southern New England

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

Valid 141925Z - 150125Z

SUMMARY...Showers and thunderstorms advancing across central PA
should gradually expand in coverage over the next couple of hours
and should impact portions of the I-95 corridor with heavy rain
heading into the early evening hours. An isolated and mainly urban
concern for flash flooding will exist.

DISCUSSION...The latest GOES-E WV suites depicts a shortwave
trough crossing the northern Mid-Atlantic currently which will be
interacting with a relatively moist and unstable boundary layer
pooled up across the coastal plain from the Delmarva northward
through southeast PA, NJ and into southeast NY.

SBCAPE values with the aid of strong diurnal heating have risen to
1000 to 1500 J/kg, and surface dewpoints across the MPD are
generally in the mid to upper 60s. Overall, the PWs are on the
order of 1.4 to 1.6 inches.

Over the next couple of hours, some additional uptick in boundary
layer instability and some modest increase in convergent low-level
flow will combined with the arrival of the shortwave energy to
foster the further development and expansion of shower and
thunderstorm activity. Already there is a fairly organized cluster
of stronger thunderstorms crossing through central PA where
stronger vort energy with the shortwave trough is noted, and this
convective cluster will continue to advance generally off to the
east as new storms ahead of it also begin to develop.

Rainfall rates with the stronger storms heading into this evening
may reach into the 1 to 2 inch/hour range, and the 12Z HREF
guidance suggests that some areas of the northern Mid-Atlantic and
especially areas along and east of the I-95 corridor may see some
of the convection get locally concentrated with some periodic
cell-merger and cell-training concerns.

This may result in a few spotty 2 to 4 inch rainfall totals with
areas of southeast PA, central and northern NJ, and perhaps far
southeast NY including the New York City metropolitan area at
greatest risk for these heavier totals. An isolated and mainly
urban flash flood concern may evolve where these heavier totals
materialize heading into the early evening hours.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

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

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

LAT...LON   42267228 41667211 40537330 39847393 39377462
            38967566 39157666 39717682 40527604 41037536
            41537461 42207332