Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 191537
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
1037 AM CDT FRI SEP 19 2014

.DISCUSSION...

MADE A FEW CHANGES TO THE ONGOING FORECAST WITH MAINLY ADJUSTMENTS
TO THE MENTION OF MORNING FOG AND EXTENDING IT INTO THE MID DAY
WITH INCREASING VISIBILITIES. LOOKING AT A SURFACE ANALYSIS THERE
LOOKS TO BE A WEAK LOW LEVEL SURFACE BOUNDARY ACROSS NORTHEAST TEXAS
JUST NORTH OF TYLER AND LONGVIEW TO NEAR SHREVEPORT AND JUST WEST
OF MONROE THEN SOUTHEAST INTO MISSISSIPPI. DRY AIR TO THE NORTH OF
THIS BOUNDARY WITH HIGHER DEW POINTS TO THE SOUTH. ABOVE THE
SURFACE THE WATER VAPOR LOOP SHOWS MUCH DRIER AIR OVER THE FOUR
STATE REGION IN THE MID LEVELS WITH NORTHERN WINDS. WINDS WERE EASTERLY
ABOVE THE SURFACE INTO THE MID LEVELS. JUST SOUTH OF THE
FORECAST AREA ACROSS SOUTHEAST TEXAS AND ACROSS SOUTHWEST
LOUISIANA THE ATMOSPHERE WAS MOIST THROUGH THE ENTIRE RANGE FROM
THE SURFACE TO THE MID AND UPPER LEVELS. /06/

&&

.PREV DISCUSSION... /ISSUED 654 AM CDT FRI SEP 19 2014/

AVIATION...
A WEAK FRONTAL BOUNDARY SLOWLY SHIFTED SOUTH OF INTERSTATE 20
DURING THE OVERNIGHT. LOW CLOUDS HAVE DEVELOPED NORTH OF THE FRONT...
WITH IFR CIGS AND PATCHY FOG...AND OCNL HIGHER MVFR DECKS. EXPECT
THESE DECKS TO TRANSITION TO MVFR BTWN 14-16Z. MOSTLY VFR
CONDITIONS HAVE PREVAILED SOUTH OF BOUNDARY THIS AM. DO NOT EXPECT
ANY CONVECTION THIS AFTN NORTH OF BOUNDARY...THUS...KLFK TERMINAL
ONLY ONE TO INCLUDE IN VCNTY TSTM THIS AFTN. SKIES AFTER 20/00Z
BECMG VFR SKC...WITH AREAS OF PATCHY FOG OR HIGH MVFR TO LOW VFR CLOUD
DECKS ALSO POSSIBLE./VII/

PREV DISCUSSION... /ISSUED 441 AM CDT FRI SEP 19 2014/

DISCUSSION...
THE 08Z SFC ANALYSIS THIS MORNING DEPICTS A VERY WEAK STATIONARY FRONT
THAT EXTENDS NW TO SE ACROSS THE REGION...FROM JUST S OF THE RED
RIVER OF NE TX ACROSS NW LA AND FARTHER SE INTO ECNTRL LA/SRN MS.
ISOLATED -SHRA THAT HAD BEEN DEVELOPING ALONG THIS BNDRY EARLY THIS
MORNING HAVE RECENTLY DISSIPATED AS A NARROW INSTABILITY AXIS ALONG
THIS BNDRY HAS DIMINISHED. HOWEVER...11-3.9U SATELLITE IMAGERY
INDICATES AN EXTENSIVE LOW STRATUS SHIELD/PATCHY FG DEVELOPING OVER SE
OK/SW AR JUST NNE OF THIS SFC FRONT...WHICH SHOULD CONTINUE TO EXPAND
IN AREAL COVERAGE TO NEAR THE AR/LA LINE INTO AREAS OF EXTREME NE TX
THROUGH DAYBREAK. MEANWHILE...SCT CONVECTION HAS AGAIN RECENTLY
REDEVELOPED OVER SE TX...ALONG A SHORTWAVE TROUGH AXIS THAT THE WATER
VAPOR IMAGERY INDICATES OVER CNTRL AND SE TX INTO SRN LA. MOSAIC RADAR
IMAGERY HAS JUST RECENTLY DEPICTED WEAK ELEVATED RETURNS OVER PORTIONS
OF DEEP E TX/LOWER TOLEDO BEND COUNTRY...THUS CAN/T RULE OUT MAINLY
ISOLATED CONVECTION AFFECTING THESE AREAS TODAY. THE WEAK STATIONARY
FRONT IS PROGGED TO WASH OUT TODAY...BUT AN ERLY LOW LEVEL FLOW WILL
RESULT IN A GRADUAL DRYING OF THE AIR MASS...WITH FLAT RIDGING ALOFT
ADDING SUBSIDENCE TO REDUCE MOST CONVECTION THAT SHOULD DEVELOP. HAVE
MAINTAINED SLIGHT CHANCE POPS TODAY ACROSS THE SRN ZONES OF E
TX/NCNTRL LA...ALTHOUGH THIS SHOULD DIMINISH BY LATE AFTERNOON/EARLY
EVENING AS THE AIR MASS CONTINUES TO DRY.

MOSTLY DRY AND ABOVE NORMAL SUMMERLIKE TEMPS WILL CONTINUE THROUGH
THIS WEEKEND...WITH THE FLAT RIDGING OVER THE SRN PLAINS EXPECTED TO
WEAKEN BY LATE SATURDAY AS A PROGRESSIVE SHORTWAVE QUICKLY TRAVERSES
THE NRN PLAINS AND AMPLIFIES INTO THE GREAT LAKES REGION SATURDAY
NIGHT/SUNDAY. THIS TROUGH WILL SEND A WEAK COLD FRONT S INTO CNTRL
OK/AR SUNDAY MORNING...WHICH WILL GRADUALLY MIX S THROUGH THE REGION
DURING THE AFTERNOON. SFC WINDS ARE EXPECTED TO BECOME NNE EVEN AHEAD
OF THE FROPA SUNDAY...MAKING THE ACTUAL BNDRY HARD TO PINPOINT AS IT
MOVES THROUGH THE AREA. HOWEVER...THE SHORT TERM PROGS ARE IN
AGREEMENT WITH SOME COMPRESSIONAL WARMING ESPECIALLY OVER E TX/N
LA/SRN AR SUNDAY...WITH MAX TEMPS IN THE LOWER TO POSSIBLY MID 90S.
FRONTAL CONVERGENCE AND DEEP LAYER MOISTURE WILL BE MINIMAL
ALONG/AHEAD OF THE FRONT...WITH ONLY ISOLATED CONVECTION POSSIBLE
SUNDAY AFTERNOON N OF I-20...WITH THE THREAT SPREADING FARTHER S TO
THE I-20 CORRIDOR OF E TX/N LA SUNDAY NIGHT. DRIER AIR BEHIND THE
FRONT WILL BEGIN TO BACKDOOR SSW INTO SE OK/SW AR LATE SUNDAY
NIGHT...WITH THIS DRIER AIR SEEPING ACROSS THE REMAINDER OF THE REGION
MONDAY AS SFC RIDGING BECOMES CENTERED OVER THE MID MS VALLEY. DID
MAINTAIN SLIGHT CHANCE POPS FOR DEEP E TX/SRN SECTIONS OF NCNTRL LA
MONDAY...BUT THIS MAY BE A STRETCH AS FORCING AND MOISTURE WILL REMAIN
MINIMAL. TEMPS SHOULD FINALLY FALL BACK DOWN TO NEAR/SLIGHTLY BELOW
SEASONAL NORMS BY MONDAY...WITH EVEN SLIGHTLY COOLER TEMPS EXPECTED
THROUGHOUT THE REMAINDER OF NEXT WEEK.

THE GFS/ECMWF ARE IN GENERAL AGREEMENT THIS MORNING WITH FLAT RIDGING
ALOFT EXPANDING E ACROSS THE SRN PLAINS/LOWER MS VALLEY
TUESDAY/WEDNESDAY...THUS ROADBLOCKING ANY SHORTWAVE ENERGY THAT WILL
TRY TO NUDGE SSE INTO THE REGION. GIVEN THE LACK OF ANY SRLY RETURN
FLOW AND FORCING AT THE SFC/ALOFT...HAVE TAKEN POPS OUT OF THE
EXTENDED...WITH DRY CONDITIONS PERSISTING PERHAPS THROUGH THE END OF
SEPTEMBER. TEMPS MAY BEGIN A SLOW WARMING TREND BY THE MIDDLE AND
LATTER PART OF THE EXTENDED AS WELL. /15/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  91  71  92  70  93 /  10  10  10  10  10
MLU  90  68  92  68  92 /  10  10  10  10  10
DEQ  86  67  89  67  90 /  10   0  10  10  20
TXK  88  69  90  69  91 /  10   0  10  10  20
ELD  89  67  91  67  92 /  10   0  10  10  20
TYR  90  70  90  70  92 /  10  10  10  10  10
GGG  90  70  91  69  92 /  10  10  10  10  10
LFK  88  71  91  70  92 /  20  10  10  10  10

&&

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

$$

06




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