SPC MESOSCALE DISCUSSION 2289 for SERN TX/SWRN LA...NERN LA/NRN AND
CNTRL MS...
CONCERNING...TORNADO WATCH 824...

VALID 262025Z - 262200Z

THUNDERSTORMS ARE EXPECTED TO DEVELOP/SPREAD INTO NORTHEAST
LOUISIANA AND NORTHERN/WESTERN MISSISSIPPI OVER THE NEXT COUPLE OF
HOURS.  A NEW TORNADO WATCH WILL LIKELY BE REQUIRED EAST OF CURRENT
TORNADO WATCH IN THE NEXT 1-2 HOURS.  ALSO...ACTIVITY BUILDING
ACROSS SOUTHEAST TEXAS WILL REQUIRE ISSUANCE OF TORNADO WATCH
SHORTLY.  

TEMPERATURES HAVE WARMED INTO THE 70S OVER MISSISSIPPI AND AIRMASS
CONTINUES TO DESTABILIZE...WITH MLCAPE OF 1000-1500 J/KG INTO
CENTRAL MISSISSIPPI.  CURRENT HODOGRAPH FROM MEMPHIS WSR-88D HAS 
0-3 KM STORM RELATIVE HELICITY OF 350 M2/S2...WITH STRONG VEERING
IN THE LOWEST 1 KM.  THUS...COMBINATION OF UPSTREAM ACTIVITY IN
NORTHERN LOUISIANA MOVING NORTHEASTWARD AND SHOWERS DEVELOPING OVER
NORTHERN MISSISSIPPI SHOULD RESULT IN INCREASING THREAT FOR
SUPERCELLS/TORNADOES OVER THE NEXT FEW HOURS. 

IN ADDITION...ACTIVITY OVER SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA
HAS BEEN GRADUALLY INCREASING WITHIN AREA OF VERY UNSTABLE AIR WITH
MLCAPE AROUND 2500 J/KG.  VERTICAL WIND SHEAR HAS BEEN MARGINAL
THUS FAR...BUT DEGREE OF INSTABILITY AND LOW LCL HEIGHTS SUGGEST
TORNADOES ARE ALSO POSSIBLE SOUTH OF CURRENT TORNADO WATCH AND A
NEW TORNADO WATCH WILL BE ISSUED SHORTLY.  

..CRAVEN.. 11/26/01