MESOSCALE DISCUSSION 0540
   NWS STORM PREDICTION CENTER NORMAN OK
   0502 PM CDT FRI APR 19 2013
   
   AREAS AFFECTED...ERN PA
   
   CONCERNING...TORNADO WATCH 133...
   
   VALID 192202Z - 192300Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 133 CONTINUES.
   
   SUMMARY...THREATS FOR ISOLATED DAMAGING WINDS AND A BRIEF TORNADO
   MAY PERSIST FOR THE NEXT FEW HOURS WITH LOW-TOPPED QLCS PROGRESSING
   E/NEWD.
   
   DISCUSSION...A THIN LOW-TOPPED QLCS STRETCHING FROM PARTS OF SRN NY
   INTO WRN MD SHOULD CONTINUE TO PROGRESS E/NEWD THIS EVENING.
   INSTABILITY WITHIN/AHEAD OF THIS LINE APPEARS TO BE QUITE LIMITED
   WITH MLCAPE LIKELY AOB 250 J/KG. THIS IS EVIDENT BY RELATIVELY
   SPARSE LIGHTNING STRIKES CONFINED TO PARTS OF CNTRL PA. MARGINAL
   INTENSIFICATION OF THE QLCS IS STILL POSSIBLE AS SURFACE
   TEMPERATURES HAD WARMED INTO THE MIDDLE 70S ACROSS MOST OF ERN
   PA...CONTRIBUTING TO STEEPER LOW-LEVEL LAPSE RATES. HOWEVER...WITH
   LEADING STRATIFORM RAINFALL AIDING IN BOUNDARY LAYER STABILIZATION
   ALONG WITH THE DEEP-LAYER SHEAR VECTOR ORIENTED NEARLY PARALLEL TO
   THE QLCS...WIND GUSTS SHOULD LARGELY REMAIN SUB-SEVERE /SUCH AS THE
   35 KT GUST AT KUNV AT 2053Z/. THIS COULD STILL YIELD LOCALIZED
   DAMAGING WINDS...MOST PROBABLE ACROSS THE SERN PORTION OF WW 133.
   
   ..GRAMS.. 04/19/2013
   
   
   ATTN...WFO...PHI...BGM...CTP...
   
   LAT...LON   39747709 39817761 40797723 42137662 42187574 42027480
               40877513 39737577 39747709