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MESOSCALE DISCUSSION 0345
NWS STORM PREDICTION CENTER NORMAN OK
0858 AM CDT TUE MAR 31 2009
AREAS AFFECTED...PORTIONS OF CNTRL/SRN LA INTO SRN MS
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 311358Z - 311530Z
THE SEVERE WEATHER THREAT IS EXPECTED TO INCREASE THIS MORNING IN
ASSOCIATION WITH ONGOING MCS. HAIL AND DAMAGING WINDS WILL BE THE
PRIMARY THREATS THOUGH A TORNADO OR TWO WILL BE POSSIBLE.
AS OF 1340Z...REGIONAL RADAR IMAGERY INDICATED A QUASI-LINEAR
CONVECTIVE SYSTEM /QLCS/ EXTENDING FROM JACKSON AND WINN PARISHES IN
N-CNTRL LA SWWD ST. AUGUSTINE AND SABINE COUNTIES IN SERN TX. THIS
SYSTEM IS DISPLAYING SEVERAL EMBEDDED CIRCULATIONS WHILE MOVING EWD
AT 30-35 KT. LATEST MESOANALYSIS INDICATES PRIMARY SYNOPTIC COLD
FRONT FROM CNTRL AR SWWD THROUGH NWRN LA INTO SERN TX. A RETREATING
WARM FRONT WAS ANALYZED FROM INTERSECTION WITH COLD FRONT JUST N OF
TOLEDO BEND BEFORE STRETCHING GENERALLY SEWD THROUGH SERN LA/FAR
SERN MS AND INTO THE NERN GULF OF MEXICO.
THIS QLCS APPEARS TO BE FOCUSED NEAR THE INTERSECTION OF THE WARM
AND COLD FRONTS AND DRIVEN LARGELY BY LOW-LEVEL WAA IN ADVANCE OF
MID-LEVEL VORTICITY MAXIMUM ROTATING EWD THROUGH THE RED RIVER
VALLEY. 12Z REGIONAL SOUNDINGS INDICATE THAT AIR MASS S OF
RETREATING WARM FRONT IS RELATIVELY MOIST WITH DEWPOINTS IN THE MID
60S AND MEAN MIXING RATIOS OF 12-13 G/KG. WHILE LOW CLOUDS REMAIN
WIDESPREAD THIS MORNING...THIS MOISTURE COUPLED WITH SOME DIABATIC
HEATING SHOULD SUPPORT THE DEVELOPMENT OF A MODERATELY UNSTABLE AIR
MASS ALONG AND S OF WARM FRONT WITH SBCAPE APPROACHING 1000-1500
J/KG.
CURRENT THINKING IS THAT QLCS WILL CONTINUE EWD ALONG RETREATING
WARM FRONT TODAY WITH SYSTEM DEVELOPING SWD INTO DESTABILIZING WARM
SECTOR. THE COMBINATION OF 45-55 KT OF DEEP-LAYER SHEAR AND
STRENGTHENING LOW-LEVEL WIND FIELDS WITH EWD EXTENT SHOULD SERVE TO
MAINTAIN AN ORGANIZED CONVECTIVE SYSTEM WITH EMBEDDED BOWING AND/OR
SUPERCELL STRUCTURES. WHILE DAMAGING WINDS AND HAIL WILL BE THE
PRIMARY SEVERE THREATS...A TORNADO OR TWO WILL BE POSSIBLE...
ESPECIALLY WITH PORTION OF QLCS INTERACTING WITH WARM FRONT.
..MEAD.. 03/31/2009
ATTN...WFO...MOB...JAN...LIX...LCH...SHV...
LAT...LON 31099345 31459306 31909245 32009166 31929062 31708929
31408872 30858882 30398958 30219050 30069158 30149253
30499320 31099345
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