MESO: Mesoscale Discussion 1522

ACUS11 KWNS 202121
SWOMCD
SPC MCD 202121
SDZ000-NEZ000-202245-

MESOSCALE DISCUSSION 1522
NWS STORM PREDICTION CENTER NORMAN OK
0421 PM CDT FRI JUL 20 2012

AREAS AFFECTED...WESTERN SD/NORTHWEST NEB

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 202121Z - 202245Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...ISOLATED TSTMS WILL CONTINUE TO INCREASE ACROSS THE
NORTH-CENTRAL HIGH PLAINS AND SD/BLACK HILLS VICINITY THIS
AFTERNOON. DAMAGING WINDS/SEVERE HAIL WILL BE POSSIBLE...AT LEAST ON
AN ISOLATED BASIS...INTO THIS EVENING.

DISCUSSION...ISOLATED TSTMS CONTINUE TO DEVELOP AT MID-AFTERNOON IN
SEVERAL GENERAL AREAS ACROSS THE REGION. THIS INCLUDES NORTHWEST
NEB/SOUTHWEST SD WITHIN A HOT/DEEP MIXED BOUNDARY LAYER IN VICINITY
OF A SOUTHWEST-NORTHEAST ORIENTED SURFACE TROUGH...WHERE A 41 KT
WIND GUST WAS RECENTLY NOTED AT PINE RIDGE SD. THIS IS IN ADDITION
TO INITIALLY MORE ISOLATED OROGRAPHICALLY/UPSLOPE AIDED DEVELOPMENT
JUST NORTHWEST OF THE RAPID CITY AREA AS OF 21Z...NEAR/NORTH OF A
WEAK FRONT. TSTMS SHOULD CONTINUE TO INCREASE IN COVERAGE AND SPREAD
EASTWARD INTO EARLY EVENING ACROSS PORTIONS OF
SOUTHWEST/SOUTH-CENTRAL SD AND NORTHWEST/NORTH-CENTRAL NEB. WHILE
TOTAL BUOYANCY IS MODEST AND VERTICAL SHEAR IS WEAK ESPECIALLY
ACROSS FAR SOUTHERN SD/NORTHERN NEB...HOT/DEEPLY MIXED BOUNDARY
LAYER AND A HIGH DCAPE ENVIRONMENT WILL SUPPORT SOME POTENTIAL FOR
DAMAGING WINDS/HAIL INTO THIS EVENING. ADDITIONAL DEVELOPMENT MAY BE
AIDED LATER THIS EVENING BY A NOCTURNALLY INCREASING LOW LEVEL JET
ACROSS SD NEAR/NORTH OF THE WEAK FRONT.

..GUYER/CARBIN.. 07/20/2012

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

ATTN...WFO...ABR...LBF...UNR...CYS...

LAT...LON 44750386 45460068 44000059 43200046 42620126 42290246
42430337 44750386

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