Area Forecast Discussion
Issued by NWS Shreveport, LA

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000
FXUS64 KSHV 171121
AFDSHV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
521 AM CST WED DEC 17 2014

.AVIATION...
IR IMAGERY SHOWING INCREASING AC DECK ACROSS MOST OF NE TX
NOW...QUICKLY MOVING INTO SW AR AND NW LA. INITIAL CEILINGS ARE
RANGING FROM 10-8KFT WITH CEILINGS QUICKLY LOWERING TO NEAR 4-5KFT
ACROSS PORTIONS OF CENTRAL AND NORTHERN TEXAS. REGIONAL RADAR MOSAICS
ALSO DEPICTING SCATTERED SHOWERS ACROSS NORTH CENTRAL TEXAS INTO SOUTH
CENTRAL AND SOUTHWEST OK. THIS IN RESPONSE TO INCREASING SOUTHWEST
FLOW ALOFT AS AN UPPER LEVEL DISTURBANCE MOVES INTO THE FOUR
CORNERS REGION OF THE COUNTRY. INCREASING ISENTROPIC LIFT WITH A
STRONGLY VEERED LOWER 5KFT WIND PROFILE ALSO HELPING FOR THE
PRECIPITATION TO BEGIN BREAKING OUT ACROSS THE ABOVE REGION AS
WELL.

FOR THE TERMINAL FORECAST PACKAGE THIS MORNING...HAVE CEILINGS
STEADILY LOWERING THROUGHOUT THE DAY WITH VCSH MENTION AT THE TYR/TXK
TERMINALS AS EARLY AS 18Z...WITH A PREVAILING LIGHT AFTERNOON -RA.
GRADUALLY BRING THESE CONDITIONS FURTHER EAST ACROSS THE REMAINING
TERMINALS BY LATE AFTERNOON INTO THE OVERNIGHT HOURS WITH LOWERING
CEILINGS AS WE SATURATE THE ATMOSPHERIC COLUMN FROM THE TOP DOWN.
CEILINGS COULD BEGIN BECOMING MVFR AS EARLY AS 00Z ACROSS SOME OF
OUR NE TX TERMINALS DEPENDING UPON JUST HOW FAST THIS SATURATION
PROCESS OCCURS. OVERNIGHT...BRINGING ALL TERMINALS DOWN TO MVFR
WITH SOME REDUCTIONS IN VSBY WITH -SHRA WITH THE ONE EXCEPTION
BEING THE MLU TERMINAL WHICH MAY NOT GET IN ON THE PRECIP UNTIL
JUST BEYOND THE 18/12Z TIMEFRAME.

WINDS WILL GRADUALLY VEER AROUND TO MORE OF A E OR ESE DIRECTION
TODAY WITH SPEEDS GENERALLY BELOW 10KTS.

13

&&

.PREV DISCUSSION... /ISSUED 410 AM CST WED DEC 17 2014/

DISCUSSION...
FLOW ALOFT WILL BECOME MORE SWLY TODAY AS AN UPPER RIDGE MOVES EWD
AND A SHORTWAVE TROUGH OVER SRN AZ EMERGES ONTO THE HIGH PLAINS
LATE THIS AFTERNOON. PLUME OF MID/UPPER LVL MOISTURE FROM THE ERN
PACIFIC WILL ALSO STREAM OVERHEAD. A WEAK STATIONARY FRONT WILL
LEAD TO AN AREA OF INCREASING ISENTROPIC ASCENT OVER THE SRN
PLAINS AHEAD OF THE TROUGH. SHWRS...AND POSSIBLY A FEW ISOLATED
TSTMS...SHOULD DEVELOP LATER THIS MORNING ACROSS CNTRL TX AND
SPREAD ENEWD INTO THE CWA THIS AFTERNOON AND CONTINUING INTO
TONIGHT/EARLY THURSDAY MORNING. HIGHEST RAINFALL AMOUNTS WITH THIS
ROUND OF PRECIP SHOULD BE ALONG AND NORTH OF I-30. MID AND LOW
LVLS OF THE ATMOSPHERE ARE QUITE DRY AND SATURATION WILL LIKELY
TAKE PLACE FROM THE TOP DOWN. THIS SHOULD LIMIT RAINFALL POTENTIAL
SOMEWHAT AND KEEP RAINFALL TOTALS GENERALLY BELOW ONE INCH THROUGH
00Z FRIDAY.

ANOTHER UPPER TROUGH...CURRENTLY JUST OFF THE NRN CA/SRN OR
COAST...WILL DIVE SEWD TO NEAR THE BIG BEND OF TX BY THURSDAY
NIGHT. A SFC LOW IS EXPECTED TO DEVELOP OVER SRN TX ALONG THE
STATIONARY FRONT AND THEN LIFT NEWD ALONG THE GULF COAST.
WIDESPREAD SHWRS/TSTMS SHOULD MOVE INTO THE AREA FROM THE SW
THURSDAY EVENING. PRECIP WILL LIKELY AFFECT MOST OF THE CWA FOR
MUCH OF FRIDAY AND IS EXPECTED TO FINALLY EXIT THE REGION
OVERNIGHT FRIDAY/EARLY SATURDAY MORNING. CHANCES FOR CONVECTION
SHOULD BE HIGHER WITH THIS SECOND SYSTEM BUT THE SFC LOW AND
FRONTAL BOUNDARY SHOULD REMAIN SOUTH OF THE CWA. ISENTROPIC ASCENT
WITH THIS SECOND ROUND SHOULD BE STRONGER THAN THE FIRST AND THE
MOISTURE SHOULD BE MORE ABUNDANT. RAINFALL AMOUNTS BETWEEN 1 AND 3
INCHES SHOULD OCCUR OVER MUCH OF THE AREA ESPECIALLY ALONG AND
SOUTH OF I-20.

A VERY ACTIVE PATTERN SHOULD CONTINUE FOR MUCH OF THE NEXT WEEK.
FLOW ALOFT WILL BECOME NWLY ON SUNDAY WHICH WILL KEEP THE PARADE
OF UPPER TROUGHS GOING AS WELL AS PERIODIC COLD FRONT PASSAGES
ALONG WITH THEM. LATEST ECMWF IS MUCH WETTER THAN THE GFS FOR NEXT
TUES/WED AS A RATHER BROAD UPPER TROUGH MOVES ACROSS THE COUNTRY.
NO MAJOR COLD AIR MASSES ARE EXPECTED FOR THE NEXT 7 DAYS AND THE
FREQUENT PRECIP CHANCES AND ABUNDANT CLOUD COVER WILL GENERALLY
KEEP TEMPS SLIGHTLY BELOW NORMAL WITH PERHAPS A WARMING TREND
EARLY NEXT WEEK. /09/

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  53  44  54  48  51 /  10  60  40  60  80
MLU  52  42  52  46  52 /  10  50  40  70  80
DEQ  47  39  50  43  46 /  40  80  20  40  80
TXK  48  40  52  44  47 /  20  70  30  40  80
ELD  48  40  51  44  48 /  10  70  40  50  80
TYR  50  44  58  48  51 /  40  70  30  70  70
GGG  53  44  56  48  52 /  30  70  30  60  70
LFK  56  49  61  53  58 /  20  60  40  80  80

&&

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

$$

09/13






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