MESO: Mesoscale Discussion 2541

ACUS11 KWNS 272307
SWOMCD
SPC MCD 272306
INZ000-KYZ000-TNZ000-ILZ000-MOZ000-ARZ000-280030-

MESOSCALE DISCUSSION 2541
NWS STORM PREDICTION CENTER NORMAN OK
0506 PM CST SAT DEC 27 2008

AREAS AFFECTED...PORTIONS OF SRN IND SWD THROUGH WRN PARTS OF KY AND
TN

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 272306Z - 280030Z

THE THREAT FOR MAINLY DAMAGING WIND GUSTS IS EXPECTED TO DEVELOP E
OF WW/S 962...964 AND 965 AS EARLY AS 2330 TO 0000Z. A NEW WW WILL
LIKELY BE REQUIRED.

QUASI-LINEAR MCS /QLCS/ WITH EMBEDDED SMALL-SCALE BOWS CONTINUES EWD
THROUGH PARTS OF THE MIDDLE AND LOWER MS VALLEYS AS OF 2250Z WITH
THE MOST INTENSE PORTION OF SYSTEM EXTENDING FROM JUST W OF MDH TO
NE OF PBF. OVERALL QLCS MOTION IS GENERALLY 270/25 KT...HOWEVER
SEGMENTS IN THE LINE /NAMELY OVER NERN AR/ ARE ACCELERATING MORE
RAPIDLY EWD AT 40-45 KT.

LATEST MESOANALYSIS INDICATES THAT LOW-LEVEL THERMAL AND MOISTURE
AXES ARE NEARLY COINCIDENT...EXTENDING ALONG THE MS RIVER NWD INTO
SRN IL. HERE...RUC FORECAST SOUNDINGS INDICATE THAT MLCAPE RANGES
FROM 500-700 J/KG OVER PARTS OF THE LOWER MS VALLEY TO 200-300 J/KG
OVER SRN IL. THIS INSTABILITY IS LIKELY NEAR PEAK VALUES GIVEN THE
TIME OF DAY...WITH A SLOW DECREASING TREND EXPECTED WITH THE ONSET
OF NIGHT FALL. THIS DECREASING INSTABILITY MAY TEND TO BE OFFSET TO
SOME DEGREE BY INCREASED LARGE-SCALE FORCING FOR UVV IN ADVANCE OF
POTENT UPPER TROUGH LIFTING NEWD INTO THE MID MS VALLEY.
THUS...EXPECT QLCS TO BE MAINTAINED FOR THE NEXT SEVERAL HOURS EWD
ACROSS DISCUSSION AREA. THE PRIMARY SEVERE WEATHER THREAT APPEARS
TO BE DAMAGING WIND GUSTS GIVEN THE STRONG AMBIENT WIND FIELDS AND
EMBEDDED BOW ECHO STRUCTURES. HOWEVER...A TORNADO OR TWO CANNOT BE
RULED OUT.

..MEAD.. 12/27/2008

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

ATTN...WFO...LMK...OHX...IND...PAH...ILX...MEG...

LAT...LON 35148977 36328978 38628841 39628721 39818635 39568597
37358718 35488822 35008889 35148977

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