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000
ACUS11 KWNS 231935
SWOMCD
SPC MCD 231935
NJZ000-PAZ000-DEZ000-232130-

Mesoscale Discussion 1135
NWS Storm Prediction Center Norman OK
0235 PM CDT Fri Jun 23 2017

Areas affected...Portions of eastern PA...NJ...and far northern DE

Concerning...Severe potential...Watch possible

Valid 231935Z - 232130Z

Probability of Watch Issuance...40 percent

SUMMARY...An isolated damaging wind threat may develop from central
into eastern PA and NJ/DE late this afternoon. Watch issuance is
possible.

DISCUSSION...Scattered convection has formed this afternoon across
western/central PA along a differential heating boundary and surface
trough, moving eastward around 35-40 kt. Visible satellite imagery
shows at least partial clearing across eastern PA into NJ and far
northern DE downstream of ongoing thunderstorms. Even though
mid-level lapse rates will remain mostly poor across this region,
daytime heating and a very moist low-level airmass (surface
dewpoints in the upper 60s to lower 70s) are contributing to MLCAPE
of 500-1500 J/kg. Strong 40-50 kt mid-level winds and a
strengthening low-level jet through this evening are supporting
40-50 kt of effective bulk shear. Strong to locally damaging winds
will probably be the main threat with any line segments/marginal
supercells moving into this region from the west. In addition, with
low-level winds generally veered to southwesterly and only modest
additional veering with height, effective SRH will probably remain
limited, but may be sufficient to support some updraft rotation and
perhaps a tornado or two. Although not immediately likely, a watch
may need to be considered in the next several hours pending latest
radar trends.

..Gleason/Guyer.. 06/23/2017

...Please see www.spc.noaa.gov for graphic product...

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

LAT...LON   39757598 41127616 41427540 41197441 40887423 40287435
            39717482 39757598