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Mesoscale Discussion 407
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   MESOSCALE DISCUSSION 0407
   NWS STORM PREDICTION CENTER NORMAN OK
   0631 PM CDT MON APR 20 2015

   AREAS AFFECTED...PORTIONS OF S-CNTRL NY AND NERN PA

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 202331Z - 210200Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...PORTIONS OF S-CNTRL NY AND NERN PA ARE BEING MONITORED FOR
   THE POSSIBLE ISSUANCE OF A NEW WW...AS THE RISK FOR SVR TSTMS
   POTENTIALLY SPREADS NEWD ACROSS THE REGION INTO THE EVENING.

   DISCUSSION...ONGOING SCATTERED CONVECTION ACROSS PORTIONS OF CNTRL
   PA INTO SWRN NY WILL CONTINUE TO SPREAD NEWD DURING THE EVENING
   HOURS. WHILE NOCTURNAL COOLING WILL AID SOME STABILIZATION OF THE
   PBL...THE PERSISTENCE OF COLD MID-LEVEL TEMPERATURES AND LARGE-SCALE
   MID-LEVEL HEIGHT FALLS/ASCENT SUGGEST SOME RISK THAT STRONG
   CONVECTION WILL EXTEND NEWD WITH TIME. CCX AND BGM VWPS SAMPLE A
   VERTICALLY VEERING WIND PROFILE WITH 45-50 KT OF MID-LEVEL SWLYS
   CAPABLE OF MAINTAINING ORGANIZED SMALL QUASI-LINEAR SEGMENTS AND
   PERHAPS SUPERCELLS WITH DMGG WIND GUSTS AND POSSIBLY ONE OR TWO
   SHORT-LIVED TORNADOES. MARGINAL INSTABILITY WITH LIMITED LOW-LEVEL
   MOISTURE COULD BE DETERRENTS TO A MORE ROBUST SVR-TSTM POTENTIAL.
   HOWEVER...THE ADEQUATE VERTICAL SHEAR AND RELATED STORM-INDUCED
   PERTURBATION PRESSURE DEFICITS ALOFT MAY OFFSET NOCTURNAL
   STABILIZATION IN SUPPORTING A SVR RISK. AS SUCH...THE AREA WILL
   CONTINUE TO BE MONITORED FOR POSSIBLE WW ISSUANCE.

   ..COHEN/CORFIDI.. 04/20/2015


   ATTN...WFO...BGM...BUF...

   LAT...LON   42017660 42417766 43077663 42657512 41967483 41437501
               41437578 42017660 

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Page last modified: April 21, 2015
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