Severe Thunderstorm Warning 169, NWS Shreveport, LA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
402 PM CDT MON AUG 11 2014

.DISCUSSION...
SCT CONVECTION EARLY THIS AFTERNOON HAS ORGANIZED INTO A SMALL MCS
OVER NCNTRL LA...AHEAD OF A WEAK SFC TROUGH THAT LINGERS NEAR OR
JUST S OF THE I-20 CORRIDOR OF N LA/E TX AS OF 20Z. ALSO SEEING
ADDITIONAL SCT CONVECTION ONGOING ACROSS ECNTRL TX SE OF CRS...AND
JUST S OF JSO...WHICH WILL AFFECT PORTIONS OF DEEP E TX THROUGH
EARLY EVENING. ALL OF THIS CONVECTION SHOULD QUICKLY RACE OUT OF
THE REGION NEAR OR JUST PRIOR TO 00Z...BUT HAVE CONCENTRATED HIGH
CHANCE POPS EARLY IN THE PERIOD FOR THESE AREAS...TAPERING TO
SLIGHT CHANCE FARTHER N TOWARDS THE I-20 CORRIDOR NEAR THE
FRONT...WHERE VERY ISOLATED -SHRA HAVE REDEVELOPED. HAVE TRENDED
THE SHORT TERM FORECAST TOWARDS THE NAM...WHICH HAS HANDLED THE
FRONT BEST WITH A SLOWER MOVEMENT MORESO THAN THE PROGRESSIVE
GFS...WHICH ACTUALLY EXITS THE FRONT OUT OF THE AREA LATE. GIVEN
THE SHALLOW NATURE OF THE POST-FRONTAL AIR MASS OVER OUR AREA AND
WEAK PRESSURE RISES FARTHER N...DON/T THINK THE TRUE FRONT WILL GO
VERY FAR OVERNIGHT...UNTIL IT IS SLOWLY REINFORCED SWD LATE AS SFC
RIDGING TO THE N BEGINS TO BUILD IN. DID MAINTAIN SLIGHT CHANCE
POPS AFTER 06Z IN VC AND S OF THE FRONT...UNTIL DRIER AIR DEEPENS
LATE WITH THE APPROACH OF A LONGWAVE TROUGH AXIS NOW DIGGING
THROUGH CNTRL OK/NW AR THIS AFTERNOON. THIS SHOULD HELP NUDGE THE
SFC TROUGH S OUT OF THE AREA BY TUESDAY AFTERNOON...WITH SLIGHTLY
DRIER SFC AIR FILTERING SWD IN ITS WAKE.

THIS DRY NW FLOW ALOFT SHOULD PERSIST THROUGH MUCH OF THIS
WEEK...RESULTING IN SLIGHTLY LOWER TEMPS BUT NOTICABLY DRIER
RH/S...WITH MIN TEMPS FALLING INTO THE 60S AREAWIDE
TUESDAY/WEDNESDAY NIGHTS...WITH EVEN SOME UPPER 50S POSSIBLE IN
THE MORE PROTECTED AREAS OF SE OK/ADJACENT SW AR. UPPER RIDGING
OVER THE FOUR CORNERS AREA SHOULD SLOWLY BUILD BACK E INTO THE SRN
PLAINS LATE WEDNESDAY INTO THURSDAY...WITH TEMPS GRADUALLY WARMING
BACK TO NEAR NORMAL READINGS. RH/S SHOULD BEGIN TO MODIFY BY
FRIDAY AND SATURDAY WITH A RETURN SSE LOW LEVEL FLOW...JUST IN
TIME FOR THE RIDGE TO FLATTEN IN RESPONSE TO SHORTWAVE ENERGY
SPILLING SE ACROSS THE CNTRL/SRN PLAINS. THE 12Z GFS IS MORE
AGGRESSIVE WITH THIS THAN THE CURRENT ECMWF SATURDAY...AS WELL AS
EARLIER RUNS...BUT BOTH AGREE ON ADDITIONAL ENERGY TRIGGERING A
POTENTIAL MCS FROM AR INTO NCNTRL LA SUNDAY. HAVE SIDED CLOSER TO
THE ECMWF SOLUTION THIS COMING WEEKEND GIVEN ITS BETTER RUN TO RUN
CONTINUITY...AND HAVE INCREASED POPS TO CHANCE FOR THESE AREAS
SUNDAY.

PRELIMS TO FOLLOW BELOW...

15

&&

.PREV DISCUSSION... /ISSUED 105 PM CDT MON AUG 11 2014/

AVIATION...
FOR THE 11/18Z TAFS...WEAK FRONTAL BOUNDARY TO CONTINUE SLOW SWRD
PROGRESS DURING THE TAF PERIOD. SCATTERED CONVECTION ALREADY SEEN
EARLY THIS AFTERNOON WITH GREATEST CONCENTRATION ACROSS THE EAST
AFFECTING THE ELD/MLU TERMINALS. FARTHER WEST...COVERAGE WILL STAY
MORE ISOLATED SO HAVE HANDLED REMAINING SITES WITH VCTS THROUGH
THIS AFTERNOON/EARLY EVENING. CONDITIONS ARE EXPECTED TO REMAIN
MOSTLY VFR WITH PERIODS OF MVFR CIGS/VSBYS POSSIBLE DURING HEAVY
DOWNPOURS. CLOUDS WILL GRADUALLY DECREASE FROM NORTH TO SOUTH
OVERNIGHT BEHIND THE FRONT WITH WINDS BECOMING MORE N/NW AND
SPEEDS LESS THAN 10 KTS OUTSIDE AREAS OF CONVECTION. /19/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  74  92  67  92  68 /  20   0   0   0   0
MLU  72  91  64  91  65 /  20  10   0   0   0
DEQ  65  88  59  89  63 /   0   0   0   0   0
TXK  71  89  64  90  65 /  10   0   0   0   0
ELD  71  89  62  90  62 /  10   0   0   0   0
TYR  72  92  66  92  68 /  10   0   0   0   0
GGG  72  92  64  92  67 /  10   0   0   0   0
LFK  74  96  67  95  67 /  30  10  10   0  10

&&

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

15

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SHREVEPORT LA
1149 AM CDT MON AUG 11 2014

ARZ050-051-059>061-070>073-LAZ001>006-010>014-017>022-OKZ077-
TXZ096-097-108>112-124>126-136>138-149>153-165>167-121200-
SEVIER-HOWARD-LITTLE RIVER-HEMPSTEAD-NEVADA-MILLER-LAFAYETTE-
COLUMBIA-UNION AR-CADDO-BOSSIER-WEBSTER-CLAIBORNE-LINCOLN-
UNION LA-DE SOTO-RED RIVER-BIENVILLE-JACKSON-OUACHITA-SABINE LA-
NATCHITOCHES-WINN-GRANT-CALDWELL-LA SALLE-MCCURTAIN-BOWIE-
FRANKLIN-TITUS-CAMP-MORRIS-CASS-WOOD-UPSHUR-MARION-SMITH-GREGG-
HARRISON-CHEROKEE-RUSK-PANOLA-NACOGDOCHES-SHELBY-ANGELINA-
SAN AUGUSTINE-SABINE TX-
1149 AM CDT MON AUG 11 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTH CENTRAL
ARKANSAS...SOUTHWEST ARKANSAS...NORTH CENTRAL LOUISIANA...
NORTHWEST LOUISIANA...SOUTHEAST OKLAHOMA...EAST TEXAS AND
NORTHEAST TEXAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT...

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON
OVER PORTIONS OF EAST TEXAS AND NORTH LOUISIANA...NEAR A WEAK
SURFACE FRONT THAT SHOULD REMAIN STATIONARY NEAR THE INTERSTATE 20
CORRIDOR. GIVEN THE EXTENT OF INSTABILITY AND MOISTURE IN PLACE
ALONG AND SOUTH OF THIS FRONT...ISOLATED STRONG STORMS CAN NOT BE
RULED OUT...CAPABLE OF PRODUCING BRIEF HEAVY RAINFALL AND LOCALLY
GUSTY WINDS. THESE SHOWERS AND THUNDERSTORMS SHOULD DIMINISH FROM
NORTH TO SOUTH THIS EVENING AS DRIER AIR ALOFT BEGINS TO SPILL
SOUTH INTO THE REGION. IN ADDITION...AFTERNOON TEMPERATURES WILL
CLIMB INTO THE MID AND UPPER 90S ACROSS PORTIONS OF EAST TEXAS AND
NORTHWEST LOUISIANA. WHEN COMBINED WITH THE HIGH HUMIDITY...HEAT
INDICES WILL RANGE FROM 100 TO 105 DEGREES THIS AFTERNOON. THOSE
THAT MUST BE OUTSIDE SHOULD DRINK PLENTY OF WATER AND TAKE
FREQUENT BREAKS FROM THE HEAT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF EMERGENCY MANAGERS...SKYWARN NETWORKS...AND AMATEUR
RADIO OPERATORS...SHOULD NOT BE NEEDED THIS AFTERNOON OR TONIGHT.

15

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