MESO: Mesoscale Discussion 1758

ACUS11 KWNS 221943
SWOMCD
SPC MCD 221942
SDZ000-NEZ000-COZ000-MTZ000-WYZ000-222215-

MESOSCALE DISCUSSION 1758
NWS STORM PREDICTION CENTER NORMAN OK
0242 PM CDT THU AUG 22 2013

AREAS AFFECTED...NERN CO...EXTREME WRN NEB AND SD...ERN WY AND SERN
MT

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 221942Z - 222215Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...STORMS MOVING EWD OFF THE HIGHER TERRAIN WILL POSE A
MODEST RISK FOR ISOLATED DOWNBURST WINDS AND HAIL THIS AFTERNOON AND
EARLY EVENING. COVERAGE OF ANY SEVERE EVENTS IS EXPECTED TO REMAIN
SPARSE...AND PROBABILITY OF WW ISSUANCE IS LOW.

DISCUSSION...THIS AFTERNOON STRONG INSOLATION IS CONTRIBUTING TO
DESTABILIZATION OVER THE CNTRL AND NRN HIGH PLAINS AREA. A WEAK
UPSLOPE COMPONENT HAS DEVELOPED IN POST FRONTAL ENVIRONMENT FROM ERN
CO INTO WY WHERE SFC DEWPOINTS REMAIN IN THE 50S ALONG ERN PERIPHERY
OF THE ELEVATED MIXED LAYER...RESULTING IN A CORRIDOR OF 1000-1500
J/KG MLCAPE. RECENT TRENDS IN SATELLITE IMAGERY SHOW CONVECTION
/INCLUDING A FEW THUNDERSTORMS/ INCREASING ALONG THE FRONT RANGE OF
THE ROCKIES FROM NCNTRL CO NWD THROUGH THE LARAMIE RANGE AND BIG
HORNS OF WY. THIS REGION RESIDES BENEATH AN UPPER RIDGE AXIS WITH
HEIGHT RISES AND SLIGHT WARMING ALOFT. NEVERTHELESS...OROGRAPHIC
FORCING SHOULD CONTINUE TO PROMOTE AT LEAST WIDELY SCATTERED
THUNDERSTORM DEVELOPMENT OVER THE ROCKIES AS WELL AS OVER THE BLACK
HILLS OF SD. A BELT OF SOMEWHAT STRONGER FLOW WITH 25-30 KT WLY
WINDS EXISTS ACROSS CNTRL WY WHERE DEEP VERTICAL SHEAR UP TO 30-35
KT EXISTS. OTHERWISE...WIND PROFILES ARE GENERALLY SUPPORTIVE OF
MULTICELLS. STEEP LOW-LEVEL LAPSE RATES WITH LARGE
TEMPERATURE-DEWPOINT SPREADS WILL PROMOTE A THREAT FOR ISOLATED
DOWNBURST WINDS WITH STORMS MOVING EWD OFF THE HIGHER TERRAIN. SOME
HAIL WILL ALSO BE POSSIBLE WITHIN THE STRONGER CORES.

..DIAL/CORFIDI.. 08/22/2013

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

ATTN...WFO...UNR...BOU...CYS...BYZ...RIW...

LAT...LON 43930616 44900661 45210507 44470345 41310355 40300401
40410492 42760569 43930616

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