
MESOSCALE DISCUSSION 0221
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CST WED MAR 12 2003
AREAS AFFECTED...SRN LA
CONCERNING...SEVERE THUNDERSTORM POTENTIAL
VALID 122059Z - 122300Z
AN ISOLATED TORNADO OR SEVERE WIND GUST REMAINS POSSIBLE WITH
SURFACE-BASED TSTMS OVER SRN LA FOR THE NEXT FEW HOURS. LIMITED
OVERALL COVERAGE DOES NOT WARRANT A WW ATTM.
LATEST MESOANALYSIS SHOWS A WEAK CONFLUENCE ZONE/MOISTURE
DISCONTINUITY FROM CNTRL LA SEWD THROUGH SLIDELL TO NEAR GPT.
AIRMASS TO THE S OF THIS BOUNDARY HAS BECOME MODERATELY UNSTABLE
WITH MLCAPES APPROACHING 2500 J/KG. RECENT RADAR TRENDS FROM
SLIDELL SHOW SURFACE-BASED TSTMS INCREASING IN COVERAGE S OF THE
BOUNDARY FROM N OF HUM TO NEW. SLIDELL VWP DATA SHOW THAT
LOW-LEVEL WINDS HAVE BACKED OVER THE PAST COUPLE OF
HOURS...EFFECTIVELY LENGTHENING LOCAL HODOGRAPHS. ALTHOUGH
DEEP-LAYER SHEAR REMAINS MARGINAL FOR ORGANIZED TSTMS --0-6 KM
SHEAR OF 35 KT-- LOW-LEVEL HODOGRAPH CURVATURE AND MODERATELY
UNSTABLE AIRMASS SUGGESTS THE POTENTIAL FOR AN ISOLATED TORNADO
OR SEVERE WIND GUST WITH THE STRONGEST STORMS THAT CAN REMAIN
ROOTED IN THE MOIST BOUNDARY LAYER.
..MEAD.. 03/12/2003
ATTN...WFO...MOB...JAN...LIX...LCH...