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Mesoscale Discussion 1247
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   MESOSCALE DISCUSSION 1247
   NWS STORM PREDICTION CENTER NORMAN OK
   0157 PM CDT TUE JUN 30 2015

   AREAS AFFECTED...PORTIONS OF FAR ERN PA...FAR WRN NJ

   CONCERNING...SEVERE THUNDERSTORM WATCH 372...

   VALID 301857Z - 302000Z

   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 372
   CONTINUES.

   SUMMARY...THE RISK FOR A COUPLE OF TORNADOES WILL EXIST ACROSS A
   SMALL CORRIDOR OF SEVERE THUNDERSTORM WATCH 372 -- ACROSS PORTIONS
   OF FAR ERN PA AND FAR WRN NJ.

   DISCUSSION...SFC OBSERVATIONS INDICATE PRESSURE FALLS AROUND 1.5 MB
   PER 2 HOURS NEAR AND E OF AN AXIS OF DISCRETE CELLS EXTENDING FROM
   NEAR ALLENTOWN TO W OF WILMINGTON DE WHERE DESTABILIZATION
   CONTINUES. OCCASIONAL MESOCYCLONES HAVE BEEN EVIDENT BASED ON
   SINGLE-SITE RADAR DATA. CONTINUED DIURNAL HEATING AMIDST MIDDLE-60S
   SFC DEWPOINTS WILL MAINTAIN PERSISTENCE OF THIS ACTIVITY. DYNAMIC
   PERTURBATION PRESSURES AT THE STORM-SCALE MAY ALLOW EWD PROPAGATION
   OF THIS ACTIVITY IN AN OTHERWISE SWLY-FLOW-ALOFT REGIME...PERHAPS
   TAKING IT TOWARD FAR WRN NJ AS WELL AS PARTS OF THE PHILADELPHIA
   AREA IN THE SHORT-TERM. DOX/DIX VWPS SAMPLE A VERTICALLY VEERING
   WIND PROFILE IN THE LOWEST COUPLE OF KM AGL THAT MAY CONTINUE TO
   ENHANCE LOW-LEVEL SRH SUFFICIENTLY FOR THE RISK OF ONE OR TWO
   TORNADOES. POOR MID-LEVEL LAPSE RATES AND ONLY MODEST LOW-LEVEL FLOW
   STRENGTH MAY MITIGATE A MORE SUBSTANTIAL TORNADO RISK OVERALL.

   ..COHEN.. 06/30/2015


   ATTN...WFO...PHI...BGM...

   LAT...LON   39977567 40367565 40937523 41137500 41127471 40297503
               39987541 39977567 

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Page last modified: June 30, 2015
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