Area Forecast Discussion
Issued by NWS Shreveport, LA

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421
FXUS64 KSHV 221045
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
545 AM CDT FRI MAY 22 2015

.AVIATION...
DRIER AIR HAS BACKDOORED INTO THE REGION FROM THE NORTHEAST AND AS
A RESULT...ONLY SEEING MVFR/IFR CEILINGS ACROSS OUR NE TX
TERMINALS ATTM. QUICK CHECK OF OUR VAD WIND PROFILER SHOWS THIS
NORTHEAST WIND IS RATHER SHALLOW...MAINLY LESS THAN 4KFT OR SO
WITH WINDS QUICKLY VEERING AROUND TO A S/SW TRAJECTORY. THIS
SHOULD HELP TO BRING LOW LEVEL MOISTURE INTO AT LEAST OUR NE TX
TERMINALS WITH THE REMAINDER OF THE SITES GETTING IN ON THE
RETURNING LOW LEVEL CLOUD COVER OVERNIGHT TONIGHT. SMALL CHANCE
POPS ACROSS OUR WESTERN ZONES DOES NOT MERIT AN MENTION IN THE 12
TAF PACKAGE. LOOK FOR WIND SPEEDS NEAR 5-10KTS TODAY WITH A FEW
HIGHER GUSTS POSSIBLE ACROSS MAINLY EAST TEXAS.

13

&&

.PREV DISCUSSION... /ISSUED 510 AM CDT FRI MAY 22 2015/

DISCUSSION...
THE 09Z SFC ANALYSIS THIS MORNING INDICATES OUR STATIONARY FRONT
LINGERING FROM THE MIDDLE TX COAST E ALONG THE LA COAST...WITH SFC
RIDGING IN PLACE FROM THE MID MS VALLEY SW INTO E TX. ALTHOUGH THE
KSHV 88-D REMAINS QUIET THIS MORNING...SFC OBS STILL INDICATE THAT
SOME PATCHY -DZ PERSISTS ACROSS THE SW SECTIONS OF E TX...POSSIBLY DUE
TO WEAK ISENTROPIC FORCING ATOP THE SHALLOW COOL AIR MASS IN PLACE.
THE SHORT TERM PROGS MAINTAIN THE SFC BNDRY TO OUR S ALONG THE COAST
TODAY...ALTHOUGH THE MORNING WATER VAPOR IMAGERY INDICATES A WELL-
DEFINED SHORTWAVE LIFTING NE THROUGH THE TX PANHANDLE WELL AHEAD OF
THE CLOSED LOW OVER SRN CA. THIS SHORTWAVE IS PROGGED TO TRAVERSE NE
INTO THE PLAINS TODAY...ATOP FLAT RIDGING ALOFT THAT WILL GRADUALLY
BUILD N ACROSS THE MID-SOUTH/LOWER MS VALLEY. THE FAR NW ZONES MAY SEE
A WEAK INFLUENCE WITH THIS SHORTWAVE RESULTING IN WIDELY SCT
CONVECTION THIS AFTERNOON...ALTHOUGH CONVECTION SHOULD BE HARD TO COME
BY ELSEWHERE...AND ISOLATED AT BEST. HAVE TRIMMED BACK POPS TO SLIGHT
CHANCE FOR MUCH OF E TX/SRN SECTIONS OF NCNTRL LA...AND REMOVED POPS
ACROSS SCNTRL AR/THE I-20 CORRIDOR OF N LA.

THIS POP-FREE PERIOD WILL BE SHORT LIVED THOUGH AS THE REMNANTS OF THE
SFC BNDRY TO OUR S LIFT QUICKLY N AND WASH OUT...ALLOWING THE WARM AND
MUGGY AIR TO SURGE BACK NWD THROUGH THE AREA. FLAT UPPER RIDGING OVER
THE REGION TODAY WILL SHIFT E OF THE MS RIVER SATURDAY AND AMPLIFY
NWD...AS THE CA CLOSED LOW LIFTS NE INTO THE FOUR CORNERS REGION BY
AFTERNOON. THUS...A DEEP SRLY FLOW WILL SET UP WEST OF THE DEPARTING
RIDGE...RESULTING IN AN ENHANCED SEABREEZE SURGING N ACROSS THE
REGION. HAVE MAINTAINED HIGH CHANCE POPS FOR E TX/N LA WITH THIS
CONVECTION EXPECTED TO WEAKEN DURING THE EVENING WITH THE LOSS OF
HEATING/DIMINISHED INSTABILITY...BUT LARGE SCALE FORCING WILL BE ON
THE INCREASE AS THE LONGWAVE TROUGH AXIS ENTERS THE SRN PLAINS. SOME
OF THIS CONVECTION MAY AFFECT THE NW ZONES NW OF I-30 SATURDAY
NIGHT...ALTHOUGH THE MORE FOCUSED HEAVY RAIN THREAT WILL REMAIN JUST OFF
TO OUR W OVER CNTRL OK/TX.

THE PROGS ARE IN GOOD AGREEMENT WITH A SHORTWAVE EJECTING NE AHEAD OF
THE CLOSED LOW ACROSS CNTRL/E TX SUNDAY...RESULTING IN A INCREASE IN
CONVECTION ESPECIALLY BY SUNDAY AFTERNOON. THE HEAVY RAINFALL/FLASH
FLOOD THREAT WILL ALSO INCREASE SUNDAY AS IT SLOWLY SPREADS ACROSS E
TX/SE OK/ADJACENT SW AR...THUS A FLASH FLOOD WATCH WILL LIKELY BE
NEEDED SUNDAY FOR THE REGION WITH THE HEAVY RAIN THREAT EXPECTED TO
SHIFT FARTHER E INTO N LA/SW AR SUNDAY NIGHT. HOWEVER...GIVEN THAT THE
MORE FOCUSED HEAVY RAINFALL THREAT FOR OUR REGION IS STILL 5 PERIODS
OUT...IT/S STILL TOO SOON FOR A WATCH ISSUANCE AT THIS POINT OF THE
FORECAST. DID INSERT MENTION OF HEAVY RAINFALL FOR E TX/SE OK SUNDAY
AFTERNOON...AND ACROSS THE REMAINDER OF THE REGION SUNDAY NIGHT AS IT
SPREADS E. THE CLOSED LOW SHOULD OPEN UP AND LIFT NE INTO THE CNTRL
PLAINS MONDAY...BUT SW FLOW ALOFT WILL BE MAINTAINED OVER THE SRN
PLAINS/LOWER MS VALLEY MONDAY...WITH SCT/NUMEROUS CONVECTION
PERSISTING OVER THE REGION. BOTH THE GFS/ECMWF INDICATE THE NEXT
SHORTWAVE TRAVERSING THE SRN PLAINS TUESDAY WITH CONVECTION BECOMING
MORE NUMEROUS THROUGH THE AFTERNOON INTO TUESDAY NIGHT...THUS RENEWING
THE HEAVY RAINFALL/FLASH FLOOD THREAT THROUGH WEDNESDAY. CONVECTION
SHOULD BECOME MORE ISOLATED/WIDELY SCT AND DIURNAL TOWARDS THE LATTER
PART OF THE EXTENDED AS FLAT RIDGING ALOFT MAY REBUILD BACK WWD INTO
PORTIONS OF THE LOWER MS VALLEY. TEMPS SHOULD ALSO BEGIN CLIMBING BACK
TO NEAR CLIMO BY THE END OF THE PERIOD AS WELL.

PRELIMS TO FOLLOW BELOW...

15

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  75  62  83  71 /  10  10  40  30
MLU  74  60  84  70 /  10  10  40  30
DEQ  72  58  79  68 /  20  20  30  40
TXK  73  60  82  69 /  10  10  30  40
ELD  74  57  83  69 /  10  10  30  30
TYR  75  65  82  71 /  20  20  50  40
GGG  75  64  82  71 /  20  20  50  40
LFK  79  69  83  72 /  20  20  50  30

&&

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

$$

15/13



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