MESOSCALE DISCUSSION 1734
   NWS STORM PREDICTION CENTER NORMAN OK
   0320 PM CDT SAT AUG 17 2013

   AREAS AFFECTED...PORTIONS OF CNTRL/W-CNTRL MT...NRN/CNTRL ID...FAR
   NERN ORE

   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

   VALID 172020Z - 172245Z

   PROBABILITY OF WATCH ISSUANCE...5 PERCENT

   SUMMARY...A VERY ISOLATED...MARGINAL SVR THUNDERSTORM POTENTIAL
   COULD EXIST INTO THE EVENING HOURS.

   DISCUSSION...WATER VAPOR LOOPS DEPICT THE MANIFESTATION OF A
   MID-LEVEL SHORTWAVE TROUGH ENTERING THE NRN INTERMOUNTAIN WEST
   THROUGH ITS EFFECTS OF DEFORMATION ON A WAVY...NARROW MID-LEVEL DRY
   SLOT BRANCHING NE OF AN E-PACIFIC CYCLONE. A MINOR INFLECTION IN
   THIS DRY SLOT STRUCTURE APPEARS TO BE APPROACHING THE MUTUAL
   INTERSECTION POINT OF THE WA/ORE/ID BORDERS...AND IS PRECEDED BY A
   LOBE OF ASCENT. THIS ASCENT IS SERVING TO STEEPEN MID-LEVEL LAPSE
   RATES. AND...WITH SFC DEWPOINTS HAVING MIXED OUT THROUGH THE 40S IN
   MANY LOCATIONS BENEATH A PLUME OF MODEST MID-LEVEL MOISTURE
   SUPPORTING PW VALUES AROUND 0.8-1.0 INCH PER GPS DATA...SFC-BASED
   BUOYANCY CONTINUES TO INCREASE. MLCAPE VALUES ARE APPROXIMATED TO BE
   AROUND 300-1200 J/KG ACROSS THE AREA.

   VISIBLE SATELLITE IMAGERY DEPICTS RECENT AGITATION TO CUMULUS
   CONGESTUS FIELDS WITHIN THE OVERLAPPING CORRIDOR OF THE
   AFOREMENTIONED PW VALUES AND MID-LEVEL ASCENT...AIDED BY LIFT
   PROVIDED BY DIURNALLY DEEPENING/STRENGTHENING OROGRAPHIC
   CIRCULATIONS. SUCH CIRCULATIONS ARE ALSO SUPPORTING CUMULUS
   DEVELOPMENT DOWNSTREAM OF STRONGER...LARGER-SCALE AGEOSTROPHIC
   CIRCULATIONS ACCOMPANYING THE SHORTWAVE TROUGH -- I.E. INVOF MORE
   ISOLATED MOUNTAINS IN CNTRL MONTANA INCLUDING THE LITTLE BELT
   MOUNTAINS SE OF GREAT FALLS.

   VERY ISOLATED THUNDERSTORMS COULD DEVELOP DURING THE NEXT FEW HOURS
   FROM THIS CUMULUS AND CONTINUE INTO THE EVENING HOURS. THE
   AFOREMENTIONED BUOYANCY...COMBINED WITH AROUND 30-40 KT OF EFFECTIVE
   DEEP SHEAR...MAY CONDITIONALLY SUPPORT A FEW ORGANIZED STORM
   STRUCTURES/POSSIBLE SUPERCELLS. MARGINALLY SVR HAIL/WIND CANNOT BE
   RULED OUT WITH THE MOST INTENSE STORMS...WITH SFC WIND GUSTS BEING
   ENHANCED BY LARGE SFC TEMPERATURE-DEWPOINT SPREADS AROUND 30-40F
   ACCOMPANYING DEEP INVERTED-VEE THERMODYNAMIC PROFILES. HOWEVER...THE
   LACK OF RICHER TROPOSPHERIC MOISTURE AND/OR EVEN STRONGER DEEP
   FORCING FOR ASCENT WILL LIKELY LIMIT THE COVERAGE/INTENSITY OF DEEP
   CONVECTION.

   ..COHEN/KERR.. 08/17/2013


   ATTN...WFO...BYZ...GGW...TFX...MSO...BOI...OTX...PDT...

   LAT...LON   44811860 45261841 45991724 46821536 48011233 48591023
               48570872 47900783 46920836 46171048 44821604 44441802
               44811860