FXUS64 KSHV 060953
AFDSHV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
353 AM CST SUN DEC 6 2009
.SHORT TERM /TODAY THROUGH TUESDAY NIGHT/...
AFTER A RESPITE FROM THE RAINFALL...THE MORNING WEATHER MAPS
PROPHESY THE RETURN OF WET STUFF FROM AN OVERCAST SKY.
A BROAD SOUTHWESTERLY FLOW ALOFT REMAINS IN PLACE THIS MORNING...AS
LOW-LEVEL MOISTURE CONTINUES DEEPENING ACROSS THE REGION. THE FIRST
IN A SERIES OF PERTURBATIONS IS EXPECTED TO MOVE INTO THE REGION BY
THIS AFTERNOON. WHEN COMBINED WITH INCREASING AMOUNTS OF ISENTROPIC
UPGLIDE AND LOWERING CONDENSATION PRESSURE DEFICITS...RAIN WILL
LIKELY DEVELOP OVER EAST TEXAS BEFORE NOON THEN GRADUALLY SPREAD
NORTH/EAST THIS AFTERNOON. RAIN WILL LIKELY CONTINUE THROUGH
TONIGHT FOR MOST OF THE FORECAST AREA...BEFORE ENDING FROM WEST TO
EAST MONDAY AS A COLD FRONT /TO OUR NORTHWEST THIS MORNING/ PUSHES
ACROSS THE AREA.
ANOTHER BREAK IN THE ACTION MAY BE SEEN MONDAY NIGHT...BUT IT WILL
LIKELY NOT LAST LONG. THE UPPER-LEVEL FLOW IS EXPECTED TO AMPLIFY
ONCE AGAIN...AS AN UPPER LOW DEEPENS ACROSS THE WESTERN UNITED
STATES. THIS WILL LIKELY RESULT IN A QUICK RETURN OF BOUNDARY LAYER
MOISTURE TO THE FORECAST AREA MONDAY NIGHT. ONCE AGAIN...A HEALTHY
DOSE OF ISENTROPIC UPGLIDE AND LOWER CONDENSATION PRESSURE DEFICITS
SHOULD YIELD ANOTHER ROUND OF RAIN AS A WARM FRONT MOVES NORTHWARD
ACROSS THE AREA.
TUESDAY WILL LIKELY YIELD MOST OF THE RAINFALL IN THE SHORT TERM
PORTION OF THE FORECAST...AS THE UPPER-LEVEL LOW PUSHES A COLD FRONT
ACROSS THE REGION. WE MIGHT EVEN HAVE THE POTENTIAL OF SEEING AN
ACTIVE WEATHER DAY AS THE STORM SYSTEM MOVES THROUGH. INSTABILITY
VALUES ARE STILL FORECAST TO BE MARGINAL. LOW-LEVEL WIND SHEAR IS
FORECAST TO BE PLENTIFUL THOUGH WITH A 50 TO 60 KNOT 850MB JET
EXPECTED TO PUSH DEWPOINTS WELL INTO THE 50S /MAYBE EVEN 60
DEGREES/...ESPECIALLY OVER MY SOUTHERN TIER OF COUNTIES/PARISHES.
WITH THE MORNING HAZARDOUS WEATHER OUTLOOK...I PLAN ON MENTIONING
THE POSSIBILITY OF STRONG THUNDERSTORMS SOUTH OF A JACKSONVILLE
TEXAS TO COLUMBIA LOUISIANA LINE. THIS IS IN GENERAL AGREEMENT WITH
THE SENTIMENTS EXPRESSED BY THE STORM PREDICTION CENTER IN THEIR DAY
3 OUTLOOK. I WILL ALSO UPGRADE THE WORDING /SO-TO-SPEAK/ ACROSS
THIS REGION IN THE GRIDDED AND TEXT FORECASTS BUT LEAVE OUT THE
MENTION OF STRONG/SEVERE STORMS AT THIS TIME. WE STILL HAVE A FEW
DAYS TO WATCH THIS EVENT.
PRECIPITATION PROBABILITIES ARE EXPECTED TO TAPER FROM WEST TO EAST
TUESDAY NIGHT AS THE FRONT MOVES THROUGH THE REGION.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
IF THE MEDIUM-RANGE MODELS ARE CORRECT...WEDNESDAY MIGHT BE A RATHER
YUCKADOO DAY ACROSS THE FORECAST AREA. GUSTY NORTH TO NORTHWEST
WINDS ARE EXPECTED IN WAKE OF THE COLD FRONT TUESDAY NIGHT. WHEN
COMBINED WITH LOW-LEVEL COLD ADVECTION AND LINGERING CLOUD COVER...
HIGH TEMPERATURES ARE NOT EXPECTED TO RISE MUCH ABOVE THE MORNING
LOWS. THE GOOD NEWS APPEARS TO BE A BRIEF BREAK IN THE ACTIVE
WEATHER PATTERN...WITH VERY LITTLE /IF ANY/ ADDITIONAL RAINFALL.
SURFACE HIGH PRESSURE IS EXPECTED TO GENERALLY REMAIN IN CONTROL OF
OUR WEATHER INTO THURSDAY. SUBTLE CHANGES ARE EXPECTED TO TRANSPIRE
THROUGH JUST TO OUR WEST...AS A WEAK SHORTWAVE TROUGH DEEPENS A BIT
OVER THE DESERT SOUTHWEST. THIS SUBTLE AMPLIFICATION OF THE
UPPER-LEVEL PATTERN WILL RESULT IN THE RETURN OF BOUNDARY LAYER
MOISTURE TO PARTS OF EAST TEXAS...MAYBE AS EARLY AS THURSDAY
AFTERNOON. EVEN THOUGH A LITTLE BIT OF ISENTROPIC UPGLIDE IS
EVIDENT ON THE 300K THETA SURFACE...CONDENSATION PRESSURE DEFICITS
DO NOT APPEAR TO BE LOW ENOUGH TO GENERATE RAINFALL. THAT SAID...I
PLAN ON KEEPING RAIN PROBABILITIES LESS THAN 15 PERCENT IN PLACE
THROUGH THURSDAY.
LOW-LEVEL MOISTURE IS FORECAST TO CONTINUE DEEPENING OVER THE REGION
THURSDAY NIGHT AS THE SURFACE HIGH STARTS SLIDING EAST. AS THE
SHORTWAVE TROUGH HEADS EASTWARD...A COLD FRONT IS FORECAST TO MOVE
SOUTH/EAST TOWARD OUR REGION FROM THE HIGH PLAINS. THIS...ALONG
WITH LOW CONDENSATION PRESSURE DEFICITS...WILL PROBABLY RESULT IN
ANOTHER ROUND OF RAIN FOR OUR AREA BY LATE THURSDAY NIGHT/EARLY
FRIDAY. THE GREATEST ODDS OF SEEING RAIN WITH THIS ROUND WILL
LIKELY BE OVER MY SOUTHERN TIER OF COUNTIES/PARISHES IN VICINITY OF
THE DEEPER MOISTURE.
PRECIPITATION SHOULD GRADUALLY END FROM WEST TO EAST EARLY SATURDAY
AS THE COLD FRONT MOVES SOUTH OF THE REGION. SOME CLOUD COVER WILL
LIKELY LINGER THROUGH SATURDAY AS THE LAST BIT OF SHORTWAVE TROUGH
ENERGY MOVES THROUGH THE REGION. IN GENERAL THOUGH...I WILL PLAN ON
MAINTAINING THE ONGOING TREND OF DECREASING PRECIPITATION
PROBABILITIES AS WELL AS SLIGHTLY BELOW NORMAL TEMPERATURES.
THANKS TO WFO JACKSON FOR COLLABORATIVE EFFORTS IN THE SHORT TERM
PORTION OF THE FORECAST THIS MORNING. /21/
&&
.AVIATION...
CONDITIONS FORECAST TO GRADUALLY DETERIORATE THROUGHOUT THE TERMINAL
FORECAST PERIOD STARTING WITH THE WESTERN SITES TYR/LFK/GGG AS
CEILINGS BECOME MVFR. BY 18Z...-RA CONDITIONS EXPECTED ACROSS EAST
TEXAS SHIFTING TO MLU/ELD AFTER 00Z. LOW LEVEL MOISTURE AND LIGHT
WINDS MAY LEAD TO LIFR CONDITIONS DUE TO FG ACROSS MANY AREA
TERMINALS EARLY MONDAY MORNING. OTHERWISE...LIGHT WINDS CAN BE
EXPECTED THROUGHOUT THE PERIOD. /05/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 49 40 56 46 62 / 50 70 10 70 60
MLU 51 44 54 45 62 / 30 80 30 60 80
DEQ 46 32 54 37 51 / 40 50 10 40 50
TXK 47 37 54 41 54 / 40 50 10 50 60
ELD 50 36 54 43 58 / 40 80 20 60 70
TYR 48 38 56 47 61 / 50 40 10 60 60
GGG 49 39 58 46 61 / 50 50 10 70 60
LFK 51 46 60 50 66 / 60 60 20 80 60
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
PUBLIC FORECASTER... D. BUTTS
AVIATION/FIRE WEATHER FORECASTER... MAYEAUX
