Area Forecast Discussion
Issued by NWS Shreveport, LA

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FXUS64 KSHV 252211
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
411 PM CST THU DEC 25 2014

.DISCUSSION...
SUFFICIENT MIXING THIS AFTERNOON HAS RESULTED IN WINDY CONDITIONS
ESPECIALLY ACROSS E TX AND SE OK...BUT THIS SHOULD WEAKEN BY
DUSK...THUS WILL ALLOW THE LAKE WIND ADVISORY TO EXPIRE AS SCHEDULED
AT 22Z. HOWEVER...A 30-35KT SWRLY LLJ WILL RESULT IN LOW LEVEL
MOISTURE ADVECTION OVERNIGHT...RESULTING IN A RETURN OF LOW CLOUDS
AFTER 06Z ACROSS MUCH OF THE REGION. THE TWO BRANCHES OF CIRRUS
OVERHEAD /ONE NE OF I-30 AND THE OTHER OVER SE TX/S LA/ SHOULD ALSO
INCREASE AND THICKEN THIS EVENING...AHEAD OF THE NEXT CLOSED LOW THAT
WILL SETTLE SWD THROUGH UT AND INTO NRN AZ LATE. THIS LOW IS PROGGED
TO OPEN UP FRIDAY OVER THE FOUR CORNERS REGION...WITH MUCH OF ITS
ENERGY EJECTING NE THROUGH THE ROCKIES AND INTO THE CNTRL PLAINS
FRIDAY NIGHT. THE SHORT TERM PROGS ARE IN AGREEMENT WITH A SHORTWAVE
EJECTING QUICKLY NE FROM NCNTRL OLD MX TONIGHT AND ACROSS SE TX/NCNTRL
LA FRIDAY MORNING AHEAD OF THE TROUGH...WHICH MAY TRIGGER ISOLATED/SCT
-SHRA MAINLY OVER DEEP E TX/NCNTRL LA AS THE LOW LEVEL MOISTURE
CONTINUES TO DEEPEN. AFTERWARDS...THE UPPER LEVEL FLOW WILL REMAIN
UNIDIRECTIONAL...WITH RIPPLES IN THE FLOW RESULTING IN SCT -SHRA
REDEVELOPMENT AREAWIDE FRIDAY NIGHT.

WITH A REMNANT OF THE UPPER TROUGH TO OUR W WILL HELP NUDGE A COLD
FRONT INTO SE OK/ECNTRL TX SATURDAY MORNING...WHICH MAY STRUGGLE
THROUGH THE HIGHER TERRAIN OVER SE OK/WRN AR AT FIRST BEFORE IT IS
DEEP ENOUGH TO DRIFT SE INTO N LA/SCNTRL AR SATURDAY AFTERNOON. THE
PROGS ARE CONSISTENT WITH SCT CONVECTION BECOMING MORE NUMEROUS AHEAD
OF THE FRONT...ALTHOUGH INSTABILITY AHEAD OF THE FRONT WILL REMAIN
ELEVATED AND MARGINAL KEEPING THUNDER EMBEDDED. ADDITIONAL
REDEVELOPMENT MAY OCCUR SATURDAY NIGHT BEHIND THE SFC FRONT CLOSER TO
THE 850MB TROUGH...BEFORE DRIER AIR FINALLY BEGINS TO DEEPEN/SPREAD E
SUNDAY THUS TAPERING THE RAINFALL. THIS FRONT WILL HELP TO REINFORCE
THE COLDER /MORE SEASONAL/ AIR THAT BRIEFLY VISITED THE REGION THE LAST
COUPLE OF DAYS...WITH A SECOND AND MUCH STRONGER REINFORCEMENT OF
ARCTIC AIR EXPECTED TO BUILD SWD INTO THE REGION TUESDAY.

THE ECMWF IS QUICK A BIT STRONGER WITH THE ARCTIC RIDGE BUILDING BY
MIDWEEK INTO WRN KS /1049MB/ COMPARED TO A WEAKER GFS /1041MB/...WITH
THE RIDGE EXPECTED TO WEAKEN/MODIFY AS IT BUILDS SWD INTO THE SRN
PLAINS/LOWER MS VALLEY. BOTH THE GFS AND ECMWF HAVE TRENDED MUCH DRIER
BEHIND THIS SECOND FROPA...THUS HAVE DROPPED MENTION OF POPS THROUGH
MUCH OF THE EXTENDED. HOWEVER...THE END OF THE EXTENDED /NEW YEAR/S
EVE/ DOES LOOK INTERESTING AS ELEVATED MOISTURE BEGINS TO OVERRUN THIS
ARCTIC AIR MASS OVER PORTIONS OF NE TX/SE OK/SW AR...THUS HAVE
MAINTAINED A -FZRA/-RA MIX ALTHOUGH QPF AMOUNTS ATTM LOOK MINIMAL.
HOWEVER...THE MOISTURE BEGINS TO DEEPEN NEW YEAR/S DAY AND THEREAFTER
AHEAD OF SHORTWAVE ENERGY THAT WILL EJECT AHEAD OF A CLOSED LOW OVER
THE DESERT SW/NEAR THE CA COAST...WHICH MAY RESULT IN A CHANCE OF A
WINTRY MIX OVER THE NRN HALF OF THE REGION JUST BEYOND THE EXTENDED
RANGE. HOWEVER...CONSIDERABLE DIFFERENCES PERSIST AMONGST THE
GFS/ECMWF WITH THE PLACEMENT ON THIS NEXT CLOSED LOW...AND THE AIR
MASS MAY BEGIN TO MODIFY SOME LATE NEXT WEEK AS WELL. JUST SOMETHING
TO KEEP AN EYE ON AS WE RING IN THE NEW YEAR.

FROM ALL OF US AT WFO SHV...MERRY CHRISTMAS!

PRELIMS TO FOLLOW BELOW...

15

&&

AVIATION.../ISSUED AT 1025 AM CST THU DEC 25 2014/

SOUTHERLY RETURN FLOW AT THE SURFACE ALREADY UNDERWAY THIS YULETIDE
MORNING AHEAD OF THE NEXT SHORTWAVE TROUGH CURRENTLY CENTERED OVER SE
UT. BY EARLY FRIDAY MORNING NEAR SUNRISE...EXPECT WIDESPREAD MVFR
CEILINGS TO RAPIDLY DEVELOP IN WARM AIR ADVECTION REGIME AND CONTINUE
THROUGHOUT FRIDAY. ALSO SCT TO NUMEROUS SHOWERS AND EVEN A FEW TSTMS
TO DEVELOP BY FRIDAY AFTERNOON AS WELL.  /VIII./

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  45  63  57  66  45 /  10  20  60  70  60
MLU  38  62  56  68  49 /   0  30  60  70  70
DEQ  38  57  52  55  37 /  10  20  60  50  20
TXK  43  59  54  60  41 /  10  20  60  60  50
ELD  38  60  54  64  45 /   0  20  60  70  60
TYR  48  62  57  58  39 /  10  20  60  50  30
GGG  46  63  57  61  40 /  10  20  60  60  50
LFK  47  66  59  67  44 /  10  30  60  60  50

&&

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

&&

$$

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