MESOSCALE DISCUSSION 0989
   NWS STORM PREDICTION CENTER NORMAN OK
   0321 PM CDT FRI JUN 12 2015

   AREAS AFFECTED...SRN/ERN OHIO INTO WRN PENNSYLVANIA

   CONCERNING...SEVERE THUNDERSTORM WATCH 290...

   VALID 122021Z - 122145Z

   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 290
   CONTINUES.

   SUMMARY...STORMS MAY CONTINUE TO POSE A RISK FOR POTENTIALLY
   DAMAGING WIND GUSTS AS THEY PROGRESS THROUGH THE UPPER OHIO VALLEY
   LATE THIS AFTERNOON.

   DISCUSSION...SUBSTANTIVE MID/UPPER SUPPORT AND STRONGER DEEP LAYER
   MEAN FLOW NOW APPEARS GENERALLY FOCUSED ACROSS AND TO THE LEE OF THE
   LOWER GREAT LAKES.  HOWEVER...VIGOROUS THUNDERSTORM ACTIVITY
   PERSISTS ALONG A TRAILING...EASTWARD ADVANCING CONGLOMERATE
   CONVECTIVE OUTFLOW BOUNDARY...ACROSS CENTRAL INTO SOUTHWESTERN OHIO.
    WEST SOUTHWESTERLY DEEP LAYER MEAN FLOW APPEARS TO WEAKEN FROM
   AROUND 30 KT OVER NORTHERN OHIO TO AROUND 20 KT NEAR THE OHIO
   RIVER...BUT THE BOUNDARY LAYER AHEAD OF THE CONVECTION CONTINUES TO
   BECOME INCREASINGLY DEEPLY MIXED...WITH SURFACE TEMPERATURES WARMING
   TOWARD/IN EXCESS OF 90F ACROSS MUCH OF THE UPPER OHIO VALLEY.  THIS
   MAY CONTINUE TO SUPPORT ISOLATED TO WIDELY SCATTERED STRONG STORM
   DEVELOPMENT CAPABLE OR PRODUCING AT LEAST LOCALIZED
   STRONG/POTENTIALLY DAMAGING WIND GUSTS THROUGH THE REMAINDER OF THE
   AFTERNOON.  BARRING A SUBSTANTIVE FURTHER INCREASE IN STORM COVERAGE
   AND INTENSITY...THOUGH...IT IS NOT YET CLEAR THAT A NEW WATCH WILL
   BE NEEDED EAST OF WATCH 290 /AND SOUTH OF WATCH 291/ ACROSS WESTERN
   PENNSYLVANIA.

   ..KERR.. 06/12/2015


   ATTN...WFO...CTP...PBZ...RLX...CLE...ILN...

   LAT...LON   39048382 39418325 39788178 40718105 41307968 41487928
               41227743 39138148 39048382