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Mesoscale Discussion 959
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   MESOSCALE DISCUSSION 0959
   NWS STORM PREDICTION CENTER NORMAN OK
   0827 PM CDT TUE JUN 09 2015

   AREAS AFFECTED...PORTIONS OF CENTRAL/SOUTHERN MONTANA

   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

   VALID 100127Z - 100400Z

   PROBABILITY OF WATCH ISSUANCE...5 PERCENT

   SUMMARY...A VERY ISOLATED SVR-TSTM RISK WILL EXIST INTO THE EVENING
   HOURS...AND WW ISSUANCE WILL NOT BE NEEDED.

   DISCUSSION...THE LEADING EDGE OF HIGH-BASED CONVECTION THAT FORMED
   OVER THE WRN MT MOUNTAINS IS SHOWING SIGNS OF INTENSIFICATION AND
   ORGANIZATION PER RECENT 7- AND 9-KM CAPPI RADAR TRENDS FROM FERGUS
   COUNTY TO GALLATIN COUNTY. THIS ACTIVITY IS ENCOUNTERING SOMEWHAT
   RICHER LOW-LEVEL MOISTURE AS IT MOVES E OF A BACKDOOR FRONT THAT HAS
   SETTLED SWWD TOWARD THE ROCKY MOUNTAIN FRONT RANGE...E OF WHICH
   DEWPOINTS ARE IN THE LOWER 50S. GIVEN THE PRESENCE OF AROUND
   8.8-C/KM LAPSE RATES IN THE H85-H5 LAYER ABOVE THIS MOISTURE PER THE
   00Z TFX RAOB...CONVECTIVE INSTABILITY WILL BE SUFFICIENT FOR
   MAINTENANCE OF THIS ACTIVITY INTO THE EVENING HOURS.
   FURTHERMORE...SFC OBS SUGGEST AN INFLUX OF RICHER LOW-LEVEL MOISTURE
   FROM ERN MT...WHICH MAY OFFSET NOCTURNAL DECREASES IN
   MLCAPE/NOCTURNAL INCREASES IN MLCINH. AS A RESULT...CONVECTION MAY
   SPREAD WELL DOWNSTREAM...FROM THE LEWISTOWN TO BOZEMAN AREA SEWD
   ACROSS OTHER PARTS OF CNTRL/SRN MT -- POTENTIALLY REACHING THE
   BILLINGS AREA LATER IN THE EVENING. THE PRESENCE OF AROUND 25-40 KT
   OF EFFECTIVE BULK SHEAR ON THE EQUATORWARD SIDE OF A MIDLEVEL SPEED
   MAX WILL ENHANCE THE RISK FOR ORGANIZED CONVECTION...CAPABLE OF VERY
   ISOLATED SVR WIND/HAIL AS AIDED BY THE STEEP-LAPSE-RATE ENVIRONMENT.
   THE LACK OF STRONGER ASCENT WILL LIMIT THE OVERALL SVR RISK.

   ..COHEN/EDWARDS.. 06/10/2015


   ATTN...WFO...BYZ...GGW...TFX...

   LAT...LON   45580845 45530979 45801075 46870932 47100836 47010724
               46120743 45580845 

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Page last modified: June 10, 2015
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