MESO: Mesoscale Discussion 1784

ACUS11 KWNS 271942
SWOMCD
SPC MCD 271942
SDZ000-NDZ000-272045-

MESOSCALE DISCUSSION 1784
NWS STORM PREDICTION CENTER NORMAN OK
0242 PM CDT TUE AUG 27 2013

AREAS AFFECTED...WRN/CNTRL PORTIONS OF SRN ND AND NRN SD

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 271942Z - 272045Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ISOLATED TSTMS MAY DEVELOP THROUGH THE LATE AFTERNOON AND
EARLY EVENING...WITH AN ACCOMPANYING RISK FOR LARGE HAIL AND A FEW
DMGG WIND GUSTS POSSIBLE. UNCERTAINTY ABOUT THE MAGNITUDE AND NUMBER
OF SVR STORMS WILL LIKELY PRECLUDE WW ISSUANCE.

DISCUSSION...SFC ANALYSIS FROM 19Z PLACES A WEAK SFC LOW 30 SE
2WX...WITH AN ATTENDANT BOUNDARY ARCING SWD AND THEN EWD ACROSS SRN
SD. TOWERING CU FIELD HAS BEEN INCREASING INVOF THE SFC LOW WITHIN
THE PAST 1-2 HRS...WITH OCCASIONAL LIGHTNING STRIKES NOTED WITH THE
MORE ROBUST CONVECTION. STRONG HEATING WITHIN A RELATIVELY MOIST
BOUNDARY LAYER /E.G. MID-60S DEWPOINTS/ IS CONTRIBUTING TO MLCAPE
VALUES OF 1500-2500 J/KG. LOW-LEVEL FLOW IS FAIRLY WEAK ACROSS THIS
AREA /AROUND 10 KT IN MEAN 0-4 KM LAYER PER BIS AND UDX VWP
DATA/...BUT ELY COMPONENT TO THE SFC WINDS TURNING TO WLY IN THE
MIDLEVELS WHERE FLOW IS STRONGER IS LIKELY SUPPORTING EFFECTIVE
SHEAR VALUES OF 40-50 KT. AREAL COVERAGE IS EXPECTED TO REMAIN
ISOLATED GIVEN VERY WEAK LARGE-SCALE FORCING FOR ASCENT AND SLIGHT
MIDLEVEL HEIGHT RISES THROUGHOUT THE DAY. HOWEVER...THE POTENTIAL
EXISTS FOR A FEW SMALL CLUSTERS AND/OR SUPERCELLS TO PROGRESS EWD
ACROSS WRN/CNTRL PARTS OF SRN ND AND NRN SD THIS AFTERNOON AND
EVENING...WITH AN ACCOMPANYING THREAT FOR LARGE HAIL AND A FEW DMGG
WIND GUSTS.

..ROGERS/THOMPSON.. 08/27/2013

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

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

LAT...LON 46800128 46800019 46679969 46149955 45619981 44830053
44090171 43970283 44080325 44390351 45080354 45660346
46070321 46320282 46610206 46800128

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