Mesoscale Discussion 1852
NWS Storm Prediction Center Norman OK
1029 AM CDT Thu Jul 31 2025
Areas affected...southeastern Pennsylvania...New
Jersey...Delaware...central Maryland...and adjacent portions of
northern Virginia...including DC
Concerning...Severe potential...Watch possible
Valid 311529Z - 311800Z
Probability of Watch Issuance...60 percent
SUMMARY...Thunderstorms are in the process of developing, and likely
to gradually intensify through 1-4 PM EDT, accompanied by increasing
risk for potentially damaging wind gusts. A brief tornado might
also be possible, particularly across parts of east central and
southeastern Pennsylvania into central New Jersey.
DISCUSSION...Perhaps aided by forcing for ascent downstream of a
short wave perturbation progressing through the southern periphery
of larger-scale positively tilted mid-level troughing overspreading
the northern Atlantic Seaboard, thunderstorms appear to be
initiating along a stalled to slow moving frontal zone, and east of
a weak surface low, across the northern Mid Atlantic. This is
occurring as insolation within a boundary-layer characterized by
seasonably high moisture content (including mid 70s F surface dew
points) erodes inhibition.
Lapse rates are generally modest to weak, and the boundary layer is
not forecast to become deeply mixed, due to the moisture, but
profiles still appear supportive of CAPE on the order of 1000-2000
J/kg. Beneath the southern fringe of the stronger westerlies, where
flow at altitudes as low as 500 mb is around 30-40 kt, deep-layer
shear is strong and supportive of supercell structures, and perhaps
an organizing cluster, with potential to produce strong surface
gusts aided by heavy precipitation loading and evaporative cooling
in downdrafts.
Thermodynamic profiles appear generally warm with limited potential
for severe hail. A brief tornado might not be out of the question,
but low-level hodographs, particularly south of the surface front,
are likely to remain generally weak.
..Kerr/Smith.. 07/31/2025
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OKX...PHI...CTP...LWX...
LAT...LON 39747713 40357698 40687612 40957453 40617390 39087505
38667600 38597718 39107734 39747713
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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