MESO: Mesoscale Discussion 2007

ACUS11 KWNS 301533
SWOMCD
SPC MCD 301533
MSZ000-LAZ000-301730-

MESOSCALE DISCUSSION 2007
NWS STORM PREDICTION CENTER NORMAN OK
1033 AM CDT SUN SEP 30 2012

AREAS AFFECTED...SERN LA THROUGH SRN MS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 301533Z - 301730Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...A FEW STORMS MIGHT BECOME CAPABLE OF ISOLATED DAMAGING
WIND GUSTS AND PERHAPS A COUPLE OF BRIEF TORNADOES FROM SERN LA
THROUGH SRN MS THIS AFTERNOON. AREA WILL CONTINUE TO BE
MONITORED...BUT ANY WW ISSUANCE WILL ULTIMATELY DEPEND ON CONVECTIVE
TRENDS AND ORGANIZATION.

DISCUSSION...A WARM FRONT EXTENDS FROM A SURFACE LOW IN WCNTRL LA
THROUGH SRN MS WHILE A PREFRONTAL TROUGH EXTENDS SWD FROM THE LOW
THROUGH SWRN LA. RICH GULF MOISTURE WITH LOW 70S DEWPOINTS HAS
SPREAD INLAND THROUGH WARM SECTOR...BUT INSTABILITY REMAINS MODEST
DUE TO WIDESPREAD CLOUDS AND WEAK MID LEVEL LAPSE RATES. PARTIAL
CLEARING EVIDENT ON VISIBLE IMAGERY IS SPREADING INTO SERN LA...AND
THIS SHOULD HELP BOOST MLCAPE TO 1500-2000 J/KG THIS AFTERNOON WHERE
SOME INCREASE IN INTENSITIES MIGHT OCCUR. LARGER 0-2 KM HODOGRAPHS
SHOULD REMAIN NORTH OF THE WARM FRONT WHERE INSTABILITY WILL BE MORE
LIMITED. HOWEVER...A SLY LLJ WILL SHIFT SLOWLY EWD THROUGH THE WARM
SECTOR IN ASSOCIATION WITH A VERY SLOW MOVING UPPER TROUGH. WHILE
SHEAR THROUGH A DEEPER LAYER IS EXPECTED TO REMAIN AOB 35 KT THIS
AFTERNOON...SUFFICIENT LOW LEVEL SHEAR WILL EXIST ALONG LLJ AXIS TO
MAINTAIN A THREAT FOR AT LEAST TRANSIENT UPDRAFT ROTATION AS WELL AS
LEWP/BOWING SEGMENTS. ANY TORNADO THREAT MAY BE SLIGHTLY HIGHER IN
SRN MS WHERE STORMS WILL HAVE POTENTIAL TO INTERACT WITH THE WARM
FRONT.

..DIAL/HART.. 09/30/2012

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

ATTN...WFO...MOB...JAN...LIX...LCH...

LAT...LON 30059225 31749094 31638910 30478909 29589016 30059225

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