[MCD] SWOMCD

Thu Aug 17 23:02:21 UTC 2006

ACUS11 KWNS 172303
SWOMCD
SPC MCD 172302 
SDZ000-NDZ000-MTZ000-WYZ000-180100-

MESOSCALE DISCUSSION 1831
NWS STORM PREDICTION CENTER NORMAN OK
0602 PM CDT THU AUG 17 2006

AREAS AFFECTED...NERN WY...EXTREME SERN MT...WRN-CNTRL SD AND
SWRN-SCNTRL ND

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 172302Z - 180100Z

22Z MESOANALYSIS PLACES A PRE-FRONTAL TROUGH FROM KATY-KPIR-KRAP AND
A COLD FRONT ARCING FROM LAKE OF THE WOODS INTO NWRN SD AND NRN WY.
ELY UPSLOPE FLOW ALONG/N OF THE TROUGH HAS ADVECTED 55-60 DEG F SFC
DEW POINTS TO THE SD BLACK HILLS...CONTRIBUTING TO MLCAPE TO 1500
J/KG.  PLUMES OF CUMULUS HAVE ERUPTED INTO TSTMS ALONG THE ERN
SLOPES OF THE BLACK HILLS WHERE CINH WAS WEAKENED BY HEATING AND
UPSLOPE FLOW.  BUT...THERE HAS BEEN A TENDENCY FOR THE STORMS TO
WEAKEN AS THEY MOVE ONTO THE HIGH PLAINS WHERE CINH IS STRONGER AND
OVERALL FORCING WEAKER.  THUS...IT APPEARS IN THE SHORT
TERM...23-01Z...THAT THE HIGHEST LARGE HAIL/DAMAGING WIND GUST
PROBABILITIES WILL EXIST NEAR/NE OF THE RAPID CITY NEWD ACROSS MEADE
AND ZIEBACH COUNTIES.

LATER THIS EVENING AS THE UPSTREAM UPPER TROUGH EDGES EWD AND THE
BOUNDARY LAYER DECOUPLES...THE SLY LLJ WILL STRENGTHEN.  WARM
ADVECTION REGIME WILL CORRESPONDINGLY INCREASE...ESPECIALLY ALONG/N
OF THE PRIMARY COLD FRONT ACROSS NWRN/NCNTRL SD AND SWRN/SCNTRL ND. 
TSTMS SHOULD INCREASE ACROSS THESE AREAS AFTER 03Z.  STRONGER
ELEVATED INSTABILITY WILL EXIST ALONG THE ND/SD BORDER SWD AND GIVEN
30-40 KTS OF EFFECTIVE VERTICAL SHEAR...A FEW STORMS COULD PRODUCE
LARGE HAIL.  DAMAGING WINDS MAY ALSO OCCUR...PARTICULARLY ACROSS NRN
SD.

..RACY.. 08/17/2006

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

ATTN...WFO...ABR...BIS...UNR...BYZ...

43870484 44940520 46140390 46700235 46800078 46009917
45289920 44289989 43340225 

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