MESOSCALE DISCUSSION 1553, AREAS AFFECTED...SWRN/CNTRL/ERN MT...FAR NWRN WY CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

        MESOSCALE DISCUSSION 1553     NWS STORM PREDICTION CENTER NORMAN OK     0227 PM CDT MON JUL 23 2012          AREAS AFFECTED...SWRN/CNTRL/ERN MT...FAR NWRN WY          CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY           VALID 231927Z - 232200Z          PROBABILITY OF WATCH ISSUANCE...20 PERCENT          SUMMARY...AN ISOLATED THREAT FOR SVR WIND GUSTS WILL EXIST WITH     THUNDERSTORMS INTO THE EVENING HOURS. GIVEN THE ANTICIPATED SPORADIC     NATURE OF ANY SVR THREAT...THE ISSUANCE OF A WW IS CURRENTLY     UNLIKELY.          DISCUSSION...A COMPACT MID-LEVEL CYCLONIC CIRCULATION SPINNING JUST     NORTH OF THE ID/WA BORDER PER WATER VAPOR IMAGERY IS FORECAST TO     TRACK SLOWLY EWD THROUGH THE EVENING. THE STRONGEST MID-LEVEL HEIGHT     FALLS ACCOMPANYING THIS FEATURE ARE EXPECTED TO REMAIN NORTH OF THE     INTERNATIONAL BORDER...THOUGH MODEST HEIGHT FALLS/ASCENT SHOULD AID     DESTABILIZATION AS FAR SOUTH AS SWRN/S-CNTRL MT. AND...WITH     LOW-LEVEL ASCENT ACCOMPANYING A COLD FRONT LYING FROM N-CNTRL TO     SWRN MT AUGMENTED BY OROGRAPHIC EFFECTS...RECENT VISIBLE SATELLITE     IMAGES INDICATE PATCHES OF BOUNDARY-LAYER CUMULUS BECOMING BETTER     DEFINED FROM THE SWRN MT MOUNTAINS TO THE ABSAROKA RANGE. WITH     ADDITIONAL DIURNAL HEATING...ISOLATED TO WIDELY SCATTERED STORMS     WILL LIKELY EVOLVE FROM THE CUMULUS FIELD DURING THE NEXT COUPLE OF     HOURS...WITH ADDITIONAL STORM DEVELOPMENT POSSIBLE ALONG A     PRE-FRONTAL TROUGH/WIND-SHIFT AXIS EXTENDING FROM EAST OF HAVRE TO     WEST OF BILLINGS.          INSTABILITY IS RATHER LIMITED AHEAD OF THE FRONT...WITH DEEP     VERTICAL MIXING ALLOWING SFC DEWPOINTS TO HAVE DROPPED INTO THE     UPPER 40S TO THE MIDDLE 50S AS TEMPERATURES HAVE CLIMBED INTO THE     MIDDLE 80S TO THE MIDDLE 90S. MODIFIED 12Z GREAT FALLS AND GLASGOW     RAOBS INDICATE THAT 500-1000 J/KG OF MLCAPE EXIST...HIGHEST EAST OF     THE PRE-FRONTAL TROUGH AXIS WHERE SFC DEWPOINTS ARE RELATIVELY     HIGHER. THIS DEGREE OF INSTABILITY MAY BE SUFFICIENT FOR A FEW     INTENSE STORMS WITH SVR WIND GUSTS...AS STEEP LOW-LEVEL LAPSE RATES     SUPPORT DCAPE OF 1000-1500 J/KG IN MANY LOCATIONS.          IN ADDITION TO LIMITED INSTABILITY...THE PRIMARY MID-LEVEL SPEED MAX     AND STRONGEST DEEP SHEAR ARE ONLY FORECAST TO GRAZE NWRN PARTS OF     THE MARGINALLY UNSTABLE SECTOR. AS SUCH...ONLY LIMITED SPATIAL     OVERLAP OF THE AFOREMENTIONED BUOYANCY WITH EFFECTIVE BULK SHEAR     MAGNITUDES AOA 30 KT IS EXPECTED. THIS SHOULD LIMIT THE THREAT FOR     ORGANIZED/PERSISTENT STORMS. HOWEVER...STORM STRENGTH EAST OF THE     PRE-FRONTAL TROUGH AXIS MAY BE MARGINALLY BOLSTERED BY WEAK     LOW-TO-MID-LEVEL DIRECTIONAL SHEAR OWING TO RELATIVELY BACKED     LOW-LEVEL FLOW.          WHILE CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED...SVR TSTM     WATCH ISSUANCE IS CURRENTLY UNLIKELY OWING TO THE ANTICIPATED     ISOLATED NATURE OF ANY SVR THREAT.          ..COHEN/HART.. 07/23/2012               ATTN...WFO...BYZ...GGW...RIW...TFX...PIH...          LAT...LON   45860651 44781002 44561181 44561254 44991319 45631207                 46501083 47551051 48901013 48970927 48960790 48880667                 48480571 47270516 45860651