Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 011944
SWOMCD
SPC MCD 011943
MTZ000-012215-

MESOSCALE DISCUSSION 1266
NWS STORM PREDICTION CENTER NORMAN OK
0243 PM CDT WED JUL 01 2015

AREAS AFFECTED...PORTIONS OF MONTANA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 011943Z - 012215Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THE AREA IS BEING MONITORED FOR AN INCREASING RISK OF
ISOLATED SEVERE THUNDERSTORMS THIS AFTERNOON...THOUGH LIMITED SVR
COVERAGE IS PRESENTLY FORECAST TO PRECLUDE WW ISSUANCE.

DISCUSSION...ISOLATED TSTMS ARE DEVELOPING INVOF THE MONTANA HI-LINE
NWD INTO ADJACENT PARTS OF SRN CANADA...WITHIN A COMPACT ZONE OF
DCVA PRECEDING A MID-LEVEL VORT MAX ADVANCING SEWD FROM SRN ALBERTA.
AHEAD OF THIS ACTIVITY...THE AIR MASS CONTINUES TO DESTABILIZE
ACROSS THE REGION OWING TO DIURNAL DIABATIC SFC HEATING...
PARTICULARLY NEAR AND N OF A SFC TROUGH ANALYZED FROM NEAR GREAT
FALLS TO S OF BAKER. THIS IS WHERE THE PBL IS RELATIVELY MOISTER --
CHARACTERIZED BY SFC DEWPOINTS IN THE UPPER 50S TO LOWER 60S --
SUPPORTING AROUND 1000-1500 J/KG OF MLCAPE. DEEPER MIXING FARTHER S
IS SCOURING OUT LOW-LEVEL MOISTURE TO SOME EXTENT YIELDING SLIGHTLY
LESS UPWARD BUOYANCY. ISOLATED SUPERCELLS MAY EVOLVE FROM THE
ONGOING TSTMS...AND POTENTIALLY DEVELOP FROM TERRAIN-DRIVEN
CIRCULATIONS. ALL OF THIS ACTIVITY WILL SPREAD SEWD INTO THE LATE
AFTERNOON/EVENING HOURS AMIDST 30-45 KT OF EFFECTIVE BULK SHEAR.
ISOLATED SVR HAIL/WIND MAY OCCUR WITH THIS ACTIVITY. HOWEVER...GIVEN
THE NARROW ZONE OF ASCENT...AND LACK OF EVEN STRONGER BUOYANCY...
CONFIDENCE IN A GREATER-COVERAGE SVR RISK IS PRESENTLY TOO LIMITED
FOR WW ISSUANCE.

..COHEN/HART.. 07/01/2015

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

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

LAT...LON   45630512 45950779 46840989 47371079 48151101 48510884
            48470628 48260477 47410411 46380414 45630512




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