MESO: Mesoscale Discussion 1154

ACUS11 KWNS 132239
SWOMCD
SPC MCD 132238
SDZ000-140015-

MESOSCALE DISCUSSION 1154
NWS STORM PREDICTION CENTER NORMAN OK
0538 PM CDT WED JUN 13 2012

AREAS AFFECTED...ECNTRL AND SE SD

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 132238Z - 140015Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...AN ISOLATED SEVERE THREAT MAY DEVELOP ACROSS ECNTRL AND SE
SD THIS EVENING. THE PRIMARY THREATS WITH THE CONVECTION SHOULD BE
STRONG WIND GUSTS AND HAIL. THE THREAT IS EXPECTED TO REMAIN
MARGINAL AND WW ISSUANCE IS NOT EXPECTED.

DISCUSSION...THE LATEST SFC ANALYSIS ACROSS THE NRN PLAINS SHOWS A
1000 MB LOW NEAR THE INTERSECTION OF WY...MT AND SD WITH A THERMAL
AXIS EXTENDING NWD INTO CNTRL SD WHERE TEMPS ARE IN THE MID 90S F.
THE THERMAL AXIS INTERSECTS A POCKET OF LOW-LEVEL MOISTURE IN THE
HURON AREA WHERE SFC DEWPOINTS ARE IN THE LOWER 60S F. THESE FACTORS
ARE HELPING TO CREATE MODERATE INSTABILITY ACROSS THE MCD AREA WITH
MLCAPE VALUES ESTIMATED IN THE 200O TO 2500 J/KG RANGE. IN
ADDITION...MESOANALYSIS SUGGESTS THE CAPPING INVERSION HAS WEAKENED
ACROSS SCNTRL SD. THIS COMBINED WITH A SMALL AREA OF INCREASED
LOW-LEVEL CONVERGENCE AND SFC HEATING HAS ENABLED THUNDERSTORMS TO
INITIATE JUST TO THE SOUTHEAST OF PIERRE OVER THE LAST HOUR.
SHORT-TERM MODEL FORECASTS SUGGEST THIS ACTIVITY WILL REMAIN
ISOLATED EARLY THIS EVENING BUT LARGE TEMP-DEWPOINT SPREADS MAY HELP
ENHANCE DOWNDRAFTS ENOUGH FOR A FEW MARGINALLY SEVERE WIND GUSTS.
THE CAPPING INVERSION IS FORECAST TO RESTRENGTHEN AFTER 03Z WHICH
SHOULD MAKE THE CONVECTION MORE ELEVATED IN NATURE. HOWEVER...AS THE
LOW-LEVEL JET STRENGTHENS THIS EVENING...CONVECTION MAY REDEVELOP
ACROSS WCNTRL SD AND MOVE EWD INTO THE AREA FROM THE WEST CONTINUING
THE SEVERE THREAT DURING THE MID TO LATE EVENING.

..BROYLES.. 06/13/2012

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

ATTN...WFO...FSD...ABR...UNR...

LAT...LON 44549852 44109907 43899989 43610010 43260013 43159987
43029928 43039867 43079812 43249773 43769751 44569788
44549852

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