Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 191759
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
1259 PM CDT SUN APR 19 2015

.AVIATION...
FOR THE 19/18Z TAFS...MVFR CIGS ACROSS SE OK/E TX ARE SPREADING
EWD AS LOW LVL MOISTURE DEEPENS AHEAD OF AN APPROACHING DRYLINE
AND COLD FRONT. STRONG TO SEVERE CONVECTION EXPECTED TO DEVELOP
ALONG THE DRYLINE/COLD FRONT AS EARLY AS 19/21Z. CONVECTIVE
COVERAGE IS EXPECTED TO REMAIN SCATTERED SO HAVE ONLY MENTIONED
VCTS IN THE TAFS. CONVECTION SHOULD MOVE EAST OF ALL TAF SITES BY
20/06Z AND AS THE COLD FRONT MOVES ACROSS THE AREA. CIGS WILL
GRADUALLY LIFT AS WINDS BECOME NWLY AND BRING DRIER AIR INTO THE
REGION. /09/

&&

.PREV DISCUSSION... /ISSUED 1139 AM CDT SUN APR 19 2015/

DISCUSSION...
CURRENT FORECAST LOOKS IN ORDER AND WILL MAKE NO CHANGES OR
UPDATES. /06/

PREV DISCUSSION... /ISSUED 510 AM CDT SUN APR 19 2015/

DISCUSSION...
THE REMNANTS OF THE MCS THAT ORIGINATED OVER WCNTRL TX SATURDAY
AFTERNOON HAS FINALLY BEGUN TO EXIT THE REGION INTO SE AR/NE LA
THIS MORNING...WITH THE AIR MASS HAVING BEEN CONVECTIVELY TURNED
OVER/STABILIZED IN ITS WAKE. THE MORNING WATER VAPOR IMAGERY
DEPICTS THE LEAD SHORTWAVE WHICH HAS DRIVEN THIS MCS OVER E
TX...WHICH SHOULD LIFT QUICKLY NE OUT OF THE REGION SHORTLY AFTER
DAYBREAK. WILL HAVE TO AWAIT THE WRN KS CLOSED LOW AS IT BEGINS TO
OPEN UP LATER TODAY...WITH THE ATTENDANT TROUGH SWINGING SE ACROSS
OK...THUS DRIVING THE W TX DRYLINE E INTO E TX/SE OK THIS
AFTERNOON. THE SHORT TERM PROGS ARE ALSO IN GOOD AGREEMENT WITH
WEAK SFC CYCLOGENESIS DEVELOPING ALONG THE NRN EXTENT OF THE
DRYLINE OVER NW TX...ADVANCING NE INTO ERN OK THIS
AFTERNOON...THUS ALLOWING COOLER AIR BEHIND A COLD FRONT TO SHIFT
SE INTO THE SRN PLAINS. A TIGHTENING PRESSURE GRADIENT WILL RESULT
IN GUSTY SW WINDS ACROSS THE WRN SECTIONS OF E TX THIS
AFTERNOON...THUS HAVE HOISTED A LAKE WIND ADVISORY FOR THESE AREAS
FROM 18-00Z TODAY.

A LOW LEVEL CAPPING INVERSION SHOULD DEVELOP THIS MORNING ACROSS
THE REGION IN WAKE OF THE MORNING CONVECTION...BUT FORECAST
SOUNDINGS SUGGEST THIS CAP QUICKLY ERODING BY EARLY
AFTERNOON...AS THE DRYLINE APPROACHES E TX. THE PROGS REMAIN IN
GOOD GENERAL AGREEMENT /ALTHOUGH THE GFS REMAINS A FASTER OUTLIER/
WITH SCT CONVECTION DEVELOPING BY MID-AFTERNOON ALONG THE DRYLINE
/PRE-FRONTAL TROUGH OVER PORTIONS OF E TX INTO SW AR...WHERE
STRONG BNDRY LYR HEATING WILL RESULT IN MODERATE/HIGH MLCAPES OF
3500-4000 J/KG. STEEPENING 850-500MB LAPSE RATES WILL ALSO
INCREASE ALONG/JUST AHEAD OF THE APPROACHING UPPER TROUGH LATER
THIS MORNING...WHICH WILL HELP ENHANCE UPDRAFT GROWTH ONCE THE
LARGE SCALE FORCING INCREASES THIS AFTERNOON. GIVEN THIS
SIGNIFICANT INSTABILITY/INCREASING DIFFLUENCE ALOFT...LOW WET BULB
ZERO HEIGHTS...AND 40-45KTS OF DEEP LAYER SHEAR...SCT SUPERCELLS
CAPABLE OF VERY LARGE HAIL AND DAMAGING WINDS ARE EXPECTED TO
DEVELOP BY MID TO LATE AFTERNOON...WHICH SHOULD QUICKLY ADVANCE
ESE ACROSS DEEP E TX/N LA/SCNTRL AR THIS EVENING. HAVE ADDED SVR
MENTION TO THE FORECAST FOR THIS AFTERNOON/EVENING...WITH THE COLD
FRONT EXPECTED TO OVERTAKE THE DRYLINE/PREFRONTAL TROUGH THIS
EVENING...AND THE CONVECTION POSSIBLY DEVELOPING A COLD POOL AND
ACCELERATING SE WITH MORE OF A DAMAGING WIND THREAT AND EXITING
THE AREA PRIOR TO 06Z MONDAY.

MUCH COOLER AIR WILL FOLLOW THE FROPA LATE TONIGHT AS LONGWAVE
TROUGHING DEEPENS OVER THE CNTRL CONUS...WITH SLIGHTLY BELOW
NORMAL TEMPS EXPECTED TO SPILL SE IN ITS WAKE THE NEXT COUPLE OF
DAYS. SFC RIDGING WILL MOVE INTO THE REGION MONDAY NIGHT...WITH
THE COOLEST MORNING EXPECTED THIS COMING WEEK AS TEMPS FALL WELL
INTO THE 40S OVER MUCH OF THE REGION. SHOULD BEGIN TO SEE TEMPS
QUICKLY MODERATE TUESDAY AFTERNOON AS A SRLY LOW LEVEL FLOW
RETURNS...WITH HUMIDITY LEVELS EXPECTED TO MODIFY BY MIDWEEK AS
WELL. THE GFS IS A LITTLE MORE BULLISH THAN THE ECMWF IN
BACKDOORING A WEAK COOL FRONT INTO THE AREA THURSDAY...ACTUALLY
TAKING THE FRONT INTO S LA/SE TX BY FRIDAY MORNING. PREFER THE
ECMWF WITH A MORE NRLY POSITION OF THE FRONT BY EARLY FRIDAY OVER
ECNTRL TX/CNTRL LA...WITH OVERRUNNING EXPECTED TO INCREASE BY
THURSDAY AS A SWRLY FLOW ALOFT IS AGAIN ESTABLISHED OVER THE SRN
PLAINS. THIS UNSETTLED PATTERN LOOKS TO PERSIST THROUGH AT LEAST
THE FIRST HALF OF THE WEEKEND AS THE FRONT BEGINS TO RETURN NWD
FRIDAY.

PRELIMS TO FOLLOW BELOW...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  84  56  73  49 /  40  40   0   0
MLU  83  59  73  49 /  30  60   0   0
DEQ  78  50  71  42 /  50  30   0   0
TXK  80  53  72  45 /  40  30   0   0
ELD  81  55  71  44 /  40  60   0   0
TYR  83  52  72  49 /  30  20   0   0
GGG  83  53  73  49 /  30  20   0   0
LFK  86  56  76  51 /  30  30   0   0

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...LAKE WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR TXZ096-
     108>111-124-125-136-137-149-150.

&&

$$

09



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