MESO: Mesoscale Discussion 0379

ACUS11 KWNS 030611
SWOMCD
SPC MCD 030610
LAZ000-TXZ000-030845-

MESOSCALE DISCUSSION 0379
NWS STORM PREDICTION CENTER NORMAN OK
0110 AM CDT WED APR 03 2013

AREAS AFFECTED...PORTIONS EXTREME SE TX...SW LA.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 030610Z - 030845Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...EXPANDING BOW ECHO OVER SE TX SHOULD SHIFT ENEWD ACROSS
LOWER SABINE RIVER REGION AND PORTIONS SWRN LA...WITH THREAT OF
SPORADIC STG-DAMAGING GUSTS MAINLY BELOW 50-KT SVR CRITERIA. WHILE
CONVECTION MAY PERSIST FOR A FEW MORE HOURS...SVR POTENTIAL IS
EXPECTED TO GENERALLY DIMINISH WITH TIME AND WITH EWD EXTENT.

DISCUSSION...OUTFLOW-REINFORCED BAROCLINIC ZONE -- SEPARATING
MARITIME/TROPICAL AIR MASS OVER OPEN GULF FROM MORE
STABLE/OUTFLOW-REINFORCED AIR MASS INLAND -- WAS DRAWN AT 06Z FROM
15-20 NM OFFSHORE JEFFERSON COUNTY TX ESEWD ACROSS SHELF WATERS NEAR
RIG STATIONS KSCF AND KMDJ. WHILE DRIFTING NWD...PROGRESS OF THIS
MARINE FRONT WILL BE IMPEDED BY PRESENCE OF ABUNDANT PRECIP ON BOTH
SIDES...EFFECTIVELY OFFSETTING WAA AND REINFORCING STATIC STABILITY
THAT INCREASES WITH INLAND EXTENT. GLS CLOCKED 49-KT GUST AT 452Z
IN MOST FAVORABLE ENVIRONMENT THAT THIS COMPLEX HAS OR WILL PASS
THROUGH...VERY CLOSE TO SFC-BASED EFFECTIVE INFLOW PARCEL AND BARELY
N OF MARINE FRONT. BPT ONLY GUSTED TO 28 KT IN MORE STABLE BOUNDARY
LAYER. FORCED ASCENT ALONG LEADING EDGE OF COLD POOL--MAINLY ABOVE
SFC--WILL HELP TO MAINTAIN ACTIVITY IN FACE OF MRGL INSTABILITY.
LIFT WILL BE AIDED BY ELY 850-MB COMPONENT EVIDENT IN VWP...AND
RELATED ENHANCEMENT OF STORM-RELATIVE INFLOW ABOVE SFC. NEARLY
SATURATED DEEP-LAYER AIR MASS WITH WEAK LAPSE RATES AND MRGL
BUOYANCY CHARACTERIZE ENVIRONMENT INTO WHICH MCS IS MOVING. MODIFIED
LCH RAOB AND FCST SOUNDINGS SUGGEST 250-500 J/KG ELEVATED MUCAPE
OVER PORTIONS S-CENTRAL/SWRN LA...INCREASING TO AROUND 1000 J/KG
WELL OFFSHORE.

..EDWARDS/KERR.. 04/03/2013

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

ATTN...WFO...LIX...LCH...

LAT...LON 29649413 29869393 30159392 30409401 30539416 30589427
30699455 30989382 30949317 30729228 30519160 29909150
29529153 29669157 29639168 29549171 29399186 29529190
29579214 29519227 29589272 29759322 29729374 29669383
29649413

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