SPC MD 1496

MD 1496 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PARTS OF SERN MONTANA...NERN WYOMING INTO ADJACENT PORTIONS OF WRN DAKOTAS

MESOSCALE DISCUSSION 1496
NWS STORM PREDICTION CENTER NORMAN OK
0626 PM CDT SUN AUG 07 2016

AREAS AFFECTED...PARTS OF SERN MONTANA...NERN WYOMING INTO ADJACENT
PORTIONS OF WRN DAKOTAS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 072326Z - 080130Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...POTENTIAL FOR DAMAGING WIND GUSTS MAY INCREASE FOR AT
LEAST A PERIOD THIS EVENING ACROSS PARTS OF SOUTHEASTERN MONTANA AND
NORTHEASTERN WYOMING.  IT IS NOT YET CERTAIN THAT A WATCH WILL BE
NEEDED...BUT CONVECTIVE TRENDS ARE BEING MONITORED FOR THE
POSSIBILITY OF INCREASING SEVERE WEATHER POTENTIAL WHICH COULD
REQUIRE ONE.

DISCUSSION...THUNDERSTORM ACTIVITY CROSSING THE BIG HORNS MOUNTAINS
HAS SHOWN RECENT SIGNS OF INTENSIFICATION.  CONVECTION APPEARS TO
HAVE BEEN SUPPORTED BY AN AREA OF ENHANCED LOWER/MID TROPOSPHERIC
WARM ADVECTION...AND PERHAPS AIDED BY OROGRAPHIC FORCING FOR ASCENT.
AS ACTIVITY CONTINUES TO SPREAD EAST OF THE HIGHER
TERRAIN...INCREASING CAPE WITHIN GRADUALLY MOISTENING LOW-LEVEL
UPSLOPE FLOW MAY CONTRIBUTE TO FURTHER INTENSIFICATION INTO THE
00-03Z TIME FRAME.  

ALTHOUGH ONLY MODEST STRENGTHENING OF CURRENTLY WEAK WESTERLY DEEP
LAYER MEAN FLOW IS EXPECTED THROUGH THIS TIME FRAME...VEERING FROM
LOW-LEVEL EASTERLIES TO MID/UPPER WESTERLIES APPEARS TO BE
CONTRIBUTING TO AT LEAST MODERATELY STRONG DEEP LAYER SHEAR.  AND
MODELS INDICATE AT LEAST SOME STRENGTHENING OF SOUTH SOUTHEASTERLY
FLOW AT 850 MB /TO 30+ KT/ IS POSSIBLE.  

AN INCREASINGLY ORGANIZED...UPSCALE GROWING MESOSCALE CONVECTIVE
SYSTEM APPEARS AT LEAST POSSIBLE DURING THE NEXT COUPLE OF HOURS
...WITH A SUBSEQUENT WINDOW OF OPPORTUNITY FOR AN INCREASING RISK
FOR SEVERE WIND GUSTS...BEFORE CONVECTION ENCOUNTERS A
COOLER/COOLING AND MORE STABLE ENVIRONMENT ACROSS THE WESTERN
DAKOTAS.

..KERR/GUYER.. 08/07/2016

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

ATTN...WFO...BIS...UNR...CYS...BYZ...GGW...RIW...

LAT...LON   45900646 46500579 47150471 47080372 45900337 44240334
            43030452 43140546 43570566 44210592 44750659 45190679
            45900646 

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