MESOSCALE DISCUSSION 1001
   NWS STORM PREDICTION CENTER NORMAN OK
   1048 AM CDT TUE JUN 09 2009
   
   AREAS AFFECTED...PORTIONS OF CNTRL NY SWWD INTO WRN PA
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 091548Z - 091715Z
   
   TSTMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG SEWD-MOVING COLD
   FRONT.  THE MORE INTENSE STORMS WILL BE CAPABLE OF DAMAGING WINDS
   AND SOME HAIL.  REGION WILL BE UPGRADED TO SLIGHT RISK AT 1630Z AND
   CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.
   
   15Z MESOANALYSIS INDICATED A COLD FRONT EXTENDING FROM LOW PRESSURE
   N OF ART SWWD THROUGH WRN NY /E OF JHW/...NWRN PA INTO CNTRL OH.  A
   WARM FRONT THEN STRETCHED GENERALLY SSEWD FROM THE SURFACE LOW TO W
   OF UCA...E OF AVP INTO THE DELMARVA.  CONSIDERABLE DIABATIC HEATING
   WITHIN WARM SECTOR AIR MASS IS RESULTING IN THE DEVELOPMENT OF STEEP
   LOW LEVEL LAPSE RATES WITH MLCAPE INCREASING TO 1000-2000 J/KG BASED
   ON MODIFICATION OF 12Z REGIONAL SOUNDINGS AND LATEST OBJECTIVE
   GUIDANCE.
   
   MORNING WATER VAPOR IMAGERY SUGGESTS THAT A NUMBER OF WEAK MIDLEVEL
   IMPULSES AREA EMBEDDED WITHIN QUASI-ZONAL FLOW REGIME...THE MOST
   NOTABLE OF WHICH IS FEATURE OVER IND INTO WRN OH AS OF 1540Z. 
   FORCING FOR ASCENT ASSOCIATED WITH THIS IMPULSE COUPLED WITH
   LOW-LEVEL CONVERGENCE ALONG FRONT SHOULD BE SUFFICIENT TO FOSTER
   SCATTERED TSTM DEVELOPMENT ALONG AND AHEAD OF BOUNDARY BY EARLY
   AFTERNOON.  STRONGEST DEEP-LAYER FLOW FIELDS /REF. 12Z BUF SOUNDING/
   WILL LIKELY REMAIN N OF THE NY/PA BORDER WITH A GENERAL DECREASE IN
   ZONAL MOMENTUM WITH SWD EXTENT.  NONETHELESS...THE PRESENCE OF THE
   STEEPENING LAPSE RATES AND MODERATE CONVECTIVE INSTABILITY MAY
   PROMOTE CLUSTERS AND/OR BANDS OF STRONG TO SEVERE STORMS CAPABLE OF
   LOCALLY DAMAGING WINDS AND PERHAPS SOME HAIL.
   
   ..MEAD.. 06/09/2009
   
   
   ATTN...WFO...ALY...BGM...BUF...CTP...PBZ...
   
   LAT...LON   40978037 41677906 42847749 43247654 43337581 43187534
               42487501 41167652 39847908 40328040 40978037