MESOSCALE DISCUSSION 1608
   NWS STORM PREDICTION CENTER NORMAN OK
   0613 PM CDT WED JUL 13 2011
   
   AREAS AFFECTED...PARTS OF WRN/CENTRAL MT AND EAST CENTRAL ID
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 639...
   
   VALID 132313Z - 140015Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 639
   CONTINUES.
   
   LOCAL WFO AREAL EXTENSION OF WW 639 IS POSSIBLE INTO NORTH CENTRAL
   MT...GIVEN A NEWD TRACK OF ONGOING STORMS FROM CASCADE COUNTY INTO
   AREAS DOWNSTREAM WITH MODERATE INSTABILITY.
   
   AT 23Z...REGIONAL RADAR IMAGERY SHOWED THE GREATEST COVERAGE OF
   TSTMS...STRONG TO SEVERE ACTIVITY...LOCATED MAINLY ACROSS THE MIDDLE
   AND NRN EXTENT OF WW 639 IN WRN/NWRN MT.  THE AIR MASS ACROSS THIS
   REGION REMAINS CONDUCIVE FOR ORGANIZED STORMS WITH MLCAPE UP TO 1500
   J/KG AND EFFECTIVE BULK SHEAR OF 35-45 KT.  THESE FACTORS WILL
   MAINTAIN THE SEVERE WEATHER THREAT INTO THIS EVENING AS STORMS TEND
   TO TRACK NEWD.  GIVEN THIS MOVEMENT AND MODERATE INSTABILITY
   EXTENDING INTO NRN MT...LOCAL WFO AREAL EXPANSION OF WW 639 IS
   POSSIBLE INTO NORTH CENTRAL MT.  OTHERWISE...AN ISOLATED THREAT FOR
   STRONG TO SEVERE STORMS SHOULD CONTINUE INTO THE EARLY EVENING TO
   THE SOUTHEAST OF THE WATCH WHERE THE AIR MASS IS MODERATELY
   UNSTABLE...BUT WEAKER SHEAR SHOULD TEND TO LIMIT ORGANIZATION AND
   THE OVERALL SEVERE WEATHER THREAT.
   
   ..PETERS.. 07/13/2011
   
   
   ATTN...WFO...BYZ...GGW...TFX...PIH...MSO...BOI...
   
   LAT...LON   44681470 47331465 48271492 49031449 48981077 48980853
               47850884 47040935 46370923 45680869 45420926 45951096
               45911152 45401159 44501181 44301302 44681470