MESOSCALE DISCUSSION 0851
   NWS STORM PREDICTION CENTER NORMAN OK
   0807 PM CDT MON MAY 18 2009
   
   AREAS AFFECTED...FAR NERN ORE...FAR SERN WA...NRN ID
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 190107Z - 190230Z
   
   ISOLATED SEVERE HAIL/WIND GUSTS WILL BE POSSIBLE THROUGH MID-EVENING
   WITH SPLITTING SUPERCELLS EVOLVING E/NEWD FROM FAR NERN ORE. LIMITED
   SPATIAL/TEMPORAL EXTENT OF THE THREAT WILL MITIGATE A WW ISSUANCE.
   
   AS OF 01Z...RADAR IMAGERY DEPICTED PAIRS OF SPLITTING SUPERCELLS
   OVER NRN WALLOWA COUNTY IN ORE...WITH ADDITIONAL CELLS FORMING ALONG
   THE SNAKE RIVER VALLEY. MODIFIED 00Z OTX RAOB FOR MIDDLE 80S SURFACE
   TEMPERATURES AND UPPER 40S SURFACE DEW POINTS SUGGESTS MLCAPE SHOULD
   BE APPROACHING 1000 J/KG WITH EFFECTIVE SHEAR OF 50 KT. NEARLY
   STRAIGHT-LINE LOW/MID-LEVEL HODOGRAPHS EVIDENT IN RAOB AND VWP DATA
   WILL CONTINUE TO SUPPORT SPLITTING CELL EVOLUTION. 12Z 4-KM WRF-NMM
   APPEARS TO HAVE A VERY GOOD HANDLE ON INITIATION/PLACEMENT OF
   ONGOING STORMS AND SUGGESTS ACTIVITY SHOULD PERSIST E/NEWD TOWARDS
   THE BITTERROOT MTNS AND WEAKEN WITH ONSET OF NOCTURNAL COOLING.
   UNTIL THAT TIME...SEVERE HAIL APPEARS TO BE THE PRIMARY THREAT
   ALTHOUGH LARGE TEMPERATURE/DEW POINT SPREADS WILL AID IN STRONG TO
   SEVERE WIND GUSTS.
   
   ..GRAMS.. 05/19/2009
   
   
   ATTN...WFO...MSO...BOI...OTX...PDT...
   
   LAT...LON   47031473 46761417 46141408 45481477 45121626 44971775
               45531818 46211790 46791685 47031473