Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 200943
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
443 AM CDT MON APR 20 2015

.DISCUSSION...
THE COLD FRONT CONTINUES TO MAKE STEADY PROGRESS SE CNTRL LA/MS THIS
MORNING...WITH COOLER AND DRIER AIR SPILLING SE IN ITS WAKE. IR
SATELLITE IMAGERY INDICATES SOME POST-FRONTAL CU ALONG AND JUST
BEHIND THE 850MB TROUGH OVER PORTIONS OF EXTREME NE TX/SW AR/NW
LA...WHICH SHOULD QUICKLY SHIFT SE OUT OF SCNTRL AR/NCNTRL LA BY
MIDDAY. LONGWAVE TROUGHING WILL PERSIST ACROSS THE CNTRL CONUS DURING
THE NEXT 24-36 HRS...WITH SFC RIDGING SETTLING SE INTO THE REGION BY
THIS EVENING. THIS WILL SET THE STAGE FOR THE COOLEST NIGHT THIS WEEK
AS TEMPS FALL INTO THE 40S OVER A LARGE PART OF THE REGION. THE ONLY
FLY IN THE OINTMENT COULD BE AN INCREASE IN AC LATE THIS AFTERNOON AND
TONIGHT FROM THE WNW AS IT ROUNDS THE BASE OF THE TROUGH. THE COOL
TEMPS WILL BE SHORT LIVED HOWEVER AS A SERLY LOW LEVEL FLOW RETURNS
TUESDAY ONCE THE SFC RIDGE DEPARTS THE AREA TO THE E. THE SHORT TERM
PROGS DO SHOW A WEAK SHORTWAVE TRAVERSING THE RED RIVER VALLEY OF SRN
OK/N TX TUESDAY WHICH MAY YIELD SOME LIGHT QPF EVEN AS IT ENTERS
PORTIONS OF EXTREME NE TX/SE OK/SW AR...DESPITE THE VERY DRY AIR MASS
IN PLACE. HAVE EXPANDED SLIGHT CHANCE POPS OVER THESE AREAS...WITH LOW
LEVEL MOISTURE EXPECTED TO GRADUALLY DEEPEN TUESDAY NIGHT. 850MB
THETA-E RIDGING NEAR/JUST N OF A RETURNING WARM FRONT WITHIN THE DIRTY
WNW FLOW MAY YIELD ISOLATED CONVECTION MAINLY ALONG/N OF THE I-30
CORRIDOR OF NE TX/SW AR TUESDAY NIGHT...WITH THE FRONT EXPECTED TO
PLAY MORE OF A ROLE IN FOCUSING CONVECTION BY WEDNESDAY.

THE WARM SECTOR WILL CONTINUE TO EXPAND NWD WEDNESDAY INTO SE OK/CNTRL
AND SRN AR...WITH A SFC LOW DEEPENING ALONG THE DRY LINE ACROSS NW TX.
MODERATE MLCAPES ARE EXPECTED TO DEVELOP BY WEDNESDAY AFTERNOON FROM
SRN OK ACROSS N AND NE TX...WHILE 700-500MB LAPSE RATES STEEPEN DURING
THE DAY AS PERTURBATIONS IN THE DIRTY WNW FLOW IN VC OF THE FRONT
TRAVERSE SE ALONG/N OF THE RED RIVER. ENHANCED CONVERGENCE ALONG THE
BNDRY SHOULD YIELD SCT CONVECTION DEVELOPING ALONG/N OF THE FRONT
WEDNESDAY...WHICH SHOULD SHIFT SE ALONG THE FRONT INTO THE REGION DURING
THE DAY. GIVEN THE ADAQUATE SHEAR AND MODERATE INSTABILITY EXPECTED TO
BE IN PLACE...COULD SEE SCT SVR CONVECTION DEVELOP BY AFTERNOON OVER
THE RED RIVER VALLEY...AFFECTING PORTIONS OF THE REGION THROUGH
WEDNESDAY EVENING.

THE GFS/ECMWF ARE IN BETTER AGREEMENT THIS MORNING WITH A WEAK COLD
FRONT BACKDOORING SW INTO SW AR THURSDAY MORNING...PULLING UP
STATIONARY NEAR OR JUST N OF THE I-20 CORRIDOR OF N LA INTO NE TX
THURSDAY AFTERNOON. THIS BNDRY SHOULD ALSO FOCUS SCT CONVECTION
THURSDAY AND THURSDAY NIGHT...BEFORE IT BEGINS TO RETURN BACK N BY
FRIDAY. THE MEDIUM RANGE PROGS CONTINUE TO SUGGEST SW FLOW ALOFT
RETURNING TO THE SRN PLAINS BY THURSDAY NIGHT/FRIDAY AHEAD OF A CLOSED
LOW THAT WILL LIFT NE AND OPEN UP ACROSS BAJA CA AND INTO THE FOUR
CORNERS REGION...FOCUSING AN UPTICK IN CONVECTION AREAWIDE
FRIDAY/FRIDAY NIGHT AS THE WARM SECTOR BEGINS TO EXPAND BACK NWD.
CONFIDENCE IS LOW IN THE DETAILS THOUGH...THUS HAVE MENTIONED HIGH
CHANCE POPS AREAWIDE DURING THIS TIMEFRAME BEFORE DRIER AIR AT THE SFC
AND ALOFT BEGINS TO SPREAD ENE ACROSS THE SRN PLAINS/LOWER MS VALLEY
BENEATH A SFC CYCLONE THAT WILL MIGRATE E FROM THE CNTRL PLAINS INTO
THE MID-SOUTH REGION. THESE DRY WRLY WINDS WOULD ALSO SUGGEST A
PRONOUNCED WARMING IN TEMPS BY NEXT WEEKEND...WITH ABOVE NORMAL
READINGS /WELL INTO THE 80S/ EXPECTED ESPECIALLY OVER E TX/N LA.

PRELIMS TO FOLLOW BELOW...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  73  48  77  60 /   0   0  10  10
MLU  74  47  76  56 /   0   0   5  10
DEQ  70  42  73  53 /   0   0  20  20
TXK  71  46  75  58 /   0   0  20  20
ELD  71  44  75  55 /   0   0  10  10
TYR  72  50  77  62 /   0   0  10  10
GGG  73  48  77  60 /   0   0  10  10
LFK  76  51  81  62 /   0   0   5  10

&&

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

$$

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