000
FXUS64 KSHV 182029
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
329 PM CDT TUE JUN 18 2013

.DISCUSSION...
BUSY AFTERNOON...AS AN MCS HAS DEVELOPED OVER NW LA...AND HAS NOW
BEGUN TO ACCELERATE ESE INTO NCNTRL LA ALONG THE RESIDUAL NCNTRL
LA OUTFLOW BNDRY FROM CONVECTION EARLIER THIS MORNING AND NEARBY
850MB TROUGH AXIS THAT EXTENDS W-E FROM E TX INTO N LA. THIS
COMPLEX IS ALSO FEEDING INTO A MORE UNSTABLE AIR MASS...AS 20Z
MESOANALYSIS INDICATES 2000-2500 J/KG OF SBCAPE HAS DEVELOPED OVER
NCNTRL LA AS CIGS HAVE BROKEN OUT TO ALLOW TEMPS TO WARM INTO THE
MID/UPPER 80S. GIVEN THE DEEP WARM LYR AND HIGH PW NOTED ON THE
12Z KSHV RAOB...LOCALLY HEAVY RAINFALL WILL ALSO BE POSSIBLE THIS
EVENING...EVEN AS DEEP LYR FORCING INCREASES WITH THE MCV NOW
ENTERING ECNTRL TX. HAVE INSERTED MENTION OF LOCALLY HEAVY
RAINFALL THIS EVENING FOR NCNTRL LA...WITH THE ANY ISOLATED SVR
AND HEAVY RAINFALL THREAT GRADUALLY DIMINISHING LATER THIS EVENING
AS THE COMPLEX EXITS THE AREA.

MEANWHILE...THE MCV SHOULD GRADUALLY ACCELERATE ESE INTO CNTRL LA
AS THE NRN MX/SRN ROCKIES UPPER RIDGE BEGINS TO GRADUALLY EXPAND N
ACROSS THE PLAINS. THE AFOREMENTIONED SFC FRONT SHOULD BECOME
STATIONARY LATER THIS EVENING FROM NCNTRL LA INTO E TX...AND
PERSIST THROUGH WEDNESDAY MORNING BEFORE GRADUALLY SHIFTING BACK N
DURING THE AFTERNOON. THE GFS HAS DRIED OUT CONSIDERABLY BUT SEEMS
TO HAVE PROBLEMS HANDLING THIS FRONT...WITH BETTER AGREEMENT AND
CONSISTENCY AMONGST THE NAM/ECMWF IN SLOWLY LIFTING THE FRONT N
WEDNESDAY AFTERNOON AND WASHING IT OUT WEDNESDAY NIGHT OR THURSDAY.
PREFER THE SLIGHTLY WETTER NAM/ECMWF SOLUTION WITH DAYTIME
HEATING/INSTABILITY AND AMPLE LOW LEVEL MOISTURE CONTRIBUTING TO
THE DEVELOPMENT OF ISOLATED/WIDELY SCT CONVECTION IN VC OF THE
FRONT WEDNESDAY. HAVE MAINTAINED LOW CHANCE POPS FOR E TX/N LA ALONG AND S
OF I-20...AND EXPANDED SLIGHT CHANCE POPS A TAD FARTHER N TO THE
RED RIVER INTO EXTREME SRN AR SHOULD THE SFC FRONT DRIFT BACK N.
ANY CONVECTION THAT DIMINISHES SHOULD DIMINISH AROUND
SUNSET...ESPECIALLY AS THE UPPER RIDGE BEGINS TO EXPAND NE TOWARDS
THE MID MS VALLEY LATE WEDNESDAY INTO THURSDAY.

THE SFC BNDRY SHOULD WASH OUT COMPLETELY DURING THE DAY THURSDAY...ALTHOUGH
WEAKNESSES ALOFT WILL ROUND THE ERN PERIPHERY OF THE RIDGE THURSDAY
AND FRIDAY DURING PEAK HEATING TO WARRANT THE CONTINUATION OF
SLIGHT CHANCE POPS FOR NCNTRL LA/PORTIONS OF DEEP E TX BY FRIDAY
THROUGH THE WEEKEND. TEMPS SHOULD ALSO WARM INTO THE MID 90S BY
THIS TIME AS WELL. SEE VERY LITTLE CHANGE IN THE UPPER AIR PATTERN
AS WE BEGIN THE NEW WORK WEEK...WITH RIDGING ALOFT STRONGEST FROM
THE SRN PLAINS INTO THE MS VALLEY...AND AN UPPER LEVEL WEAKNESS
OVER THE GULF COAST STATES WHICH COULD RESULT IN MAINLY ISOLATED
AFTERNOON CONVECTION OVER N LA/DEEP E TX.

PRELIMS TO FOLLOW BELOW...

15

&&

.AVIATION...
MAIN CONCERN FOR THE 19/00Z TAF ISSUANCE WILL BE FLIGHT HAZARDS FROM
SCATTERED TSTMS WHICH WILL CONTINUE FOR MUCH OF THIS EVENING. A WEAK
FRONTAL BOUNDARY NEAR A KELD TO KTYR LINE WILL BE THE DIVIDING LINE
BETWEEN MORE NUMEROUS STORMS TO THE SOUTH AND ONLY ISOLATED COVERAGE
NORTH. EXPECT MOSTLY VFR FLIGHT WEATHER OUTSIDE OF THE CONVECTIVE
AREAS...BUT NEAR STORMS EXPECT MVFR/IFR CONDITIONS ALONG WITH
MODERATE TO SEVERE TURBULENCE AND SURFACE WIND GUSTS UP TO 45 KTS.
THE FRONT WILL DRIFT SLOWLY SOUTH TONIGHT AND MOST OF THE CONVECTION
WILL REMAIN SOUTH OF THE BOUNDARY. HOWEVER AFTER 08Z AND CONTINUING
THROUGH 14Z WEDNESDAY....MUCH OF THE AREA ALONG AND SOUTH OF
INTERSTATE 20 MAY EXPERIENCE MVFR TO BRIEFLY IFR CIGS AND VSBYS
DUE TO FOG. SURFACE WIND WILL BE DETERMINED BY FRONTAL LOCATION...
BUT GENERALLY IN THE 5 TO 10 KT RANGE.  /14/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  69  90  73  93  74 /  30  30  10  20  10
MLU  70  89  70  92  72 /  40  30  10  20  10
DEQ  64  90  68  92  72 /  10  10  10  20  10
TXK  68  90  70  91  73 /  20  20  10  20  10
ELD  67  90  69  92  71 /  20  20  10  10  10
TYR  69  91  74  93  74 /  20  30  10  20  10
GGG  69  90  73  93  73 /  20  30  10  20  10
LFK  71  92  73  94  74 /  40  30  10  20  10

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&

$$

15/14