MESO: Mesoscale Discussion 2137

ACUS11 KWNS 090419
SWOMCD
SPC MCD 090418
ARZ000-OKZ000-090615-

MESOSCALE DISCUSSION 2137
NWS STORM PREDICTION CENTER NORMAN OK
1018 PM CST SAT DEC 08 2012

AREAS AFFECTED...EXTREME SERN OK INTO WRN THROUGH CNTRL AR

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 090418Z - 090615Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...SLOW BUT GRADUAL INCREASE IN THUNDERSTORM COVERAGE AND
INTENSITIES WILL LIKELY OCCUR INTO THE EARLY MORNING HOURS FROM
EXTREME SERN OK INTO WRN AND CNTRL AR. A FEW STORMS MAY BECOME
CAPABLE OF PRODUCING SMALL TO MARGINALLY SEVERE HAIL. THREAT IS
EXPECTED TO REMAIN TOO MARGINAL FOR WW ISSUANCE.

DISCUSSION...THIS EVENING A QUASI-STATIONARY FRONT EXTENDS FROM
CNTRL AR INTO SERN OK AND NRN TX. VWP DATA SHOW THE LOW LEVEL JET
HAS INCREASED TO 40 KT...AND THE RESULTING THETA-E ADVECTION WILL
CONTRIBUTE TO NWD DESTABILIZATION WITH TIME THROUGH ERN OK AND AR.
OBJECTIVE ANALYSIS INDICATES MUCAPE CURRENTLY FROM 300-500
J/KG...BUT WILL LIKELY INCREASE TO 500-1000 J/KG LATER TONIGHT.
SLIGHTLY ELEVATED STORMS WILL CONTINUE DEVELOPING WITHIN ZONE OF
ISENTROPIC ASCENT ALONG AND NORTH OF THE QUASI-STATIONARY BOUNDARY.
THE INCREASE IN INSTABILITY AND EFFECTIVE CLOUD LAYER SHEAR OF 40+
KT WILL PROMOTE A THREAT FOR UPDRAFT ROTATION AND AT LEAST A MODEST
THREAT FOR HAIL. HOWEVER...WEAK MID LEVEL LAPSE RATES SHOULD
MITIGATE OVERALL LARGE HAIL POTENTIAL.

..DIAL/EDWARDS.. 12/09/2012

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

ATTN...WFO...LZK...SHV...TSA...

LAT...LON 34119390 34159464 35039451 35449391 35409241 34789245
34119390

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