831
AWUS01 KWNH 071606
FFGMPD
MEZ000-MAZ000-NHZ000-RIZ000-VTZ000-CTZ000-NYZ000-NJZ000-PAZ000-072200-

Mesoscale Precipitation Discussion 0394
NWS Weather Prediction Center College Park MD
1206 PM EDT Sat Jun 07 2025

Areas affected...Far Northeast PA...Northern NJ...Southeast
NY...Central and Southern New England

Concerning...Heavy rainfall...Flash flooding likely

Valid 071600Z - 072200Z

SUMMARY...Heavy rainfall will continue to overspread much of the
northeast Mid-Atlantic region into central and southern New
England going through the mid to late-afternoon hours. This will
include some locally more concentrated areas of stronger
thunderstorm activity with higher rainfall rates. Areas of flash
flooding are likely considering the very moist and locally
saturated soil conditions.

DISCUSSION...An expansive axis of heavy rainfall in a southwest to
northeast fashion continues to advance across southeast NY and
into central and southern New England. The activity which includes
some occasionally stronger thunderstorm activity continues to be
strongly supported by an ejecting shortwave trough and associated
wave of low pressure which is transiting a well-defined frontal
zone across the Northeast.

The latest GOES-E IR/WV satellite imagery shows an excellent
corridor of upper-level jet divergence/forcing over especially
central and southern New England with an expansive axis of cooling
cloud-tops over the region. There continues to be a low-level
frontogenetic response to this with the axis of heavy rainfall
which has been very efficient this morning. Shallow, warm
convective tops and frontogenetical forcing in the lower to
mid-levels of the column have been yielding warm rain processes,
and this showed up well in the 12Z ALY RAOB sounding which
depicted a deep moist column with a tall/skinny CAPE profile.

There should be a gradual uptick in the overall convective
footprint of the heavy rainfall this afternoon across especially
southern New England including the Boston, MA to Hartford, CT
corridor and potentially edging south to near the New York City
metropolitan area and adjacent areas of northern NJ by late
afternoon. This will be supported by convergence along the
aforementioned frontal zone, but also with an increase in
diurnally driven instability. Cloud cover will tend to mitigate
the amount of surface heating that does occur, but with an already
very moist column, and the aforementioned low-level and
upper-level support, there should be a gradual expansion of
heavier showers and thunderstorms over the next several hours.

Rainfall rates may reach as high as 1.5 inches to 2 inches/hour
with the stronger cells, and the locally slow cell-motions and
pockets of at least brief cell-training may support some totals by
early this evening that reach 3 to 4+ inches. This is supported by
the 12Z HREF and 06Z REFS guidance.

The antecedent conditions are quite sensitive over the higher
terrain of southern VT, southern NH and through central and
western MA. Runoff here over the next few hours may be enhanced
given the additional rains, and gradually heavier rainfall rates
farther south and east may pose some urban flooding concerns.
Overall, on a regional level, areas of flash flooding are likely.

Orrison

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

ATTN...WFO...ALY...BGM...BOX...BTV...GYX...OKX...PHI...

ATTN...RFC...RHA...TAR...NWC...

LAT...LON   44607027 44566903 43996893 42937041 41747132
            41217275 40987314 40527430 40537520 41047545
            41917467 42717390 43727193