FXUS64 KSHV 221617
AFDSHV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
1017 AM CST TUE DEC 22 2009
.DISCUSSION...
SURFACE HIGH TO THE EAST PROVIDING SOUTHERLY FLOW ACROSS THE
REGION THIS MORNING. 12Z SHV UPPER AIR SOUNDING INDICATES INCREASED LOW
LEVEL-MOISTURE...ALONG WITH 30 KNOT SOUTHWESTERLY FLOW ABOVE THE
BOUNDARY LAYER. MID AND UPPER LEVELS REMAIN EXTREMELY DRY WITH A
STOUT 700 MB INVERSION. THUS...ANY SHOWER ACTIVITY LATER TODAY IS
LIKELY REMAIN SHALLOW AND RELATIVELY FAST MOVING. RADAR IMAGERY
INDICATES A FEW OF THESE LIGHT SHOWERS CURRENTLY MOVING NORTHEAST
ACROSS SOUTHERN ARKANSAS. MAY AN INCREASE IN THIS TYPE OF
PRECIPITATION LATER TODAY.
OTHERWISE...CURRENT FORECAST IS ON TRACK. NO CHANGES AT THIS TIME.
/05/
&&
.AVIATION...
MOSTLY VFR THIS AFTERNOON AND EARLY EVENING...WITH CIGS 3 TO 5 KFT
BKN. CEILINGS GRADUALLY LOWERING TO MVFR AND PATCHY IFR TONIGHT AS
LOW LEVEL MOISTURE INCREASES ACROSS THE REGION. PRESSURE GRADIENT
WILL CONTINUE TO INCREASE DURING THE DAY INTO THE OVERNIGHT HOURS
AS SFC LOW PRESSURE CONTINUES TO DEEPEN ACROSS THE TEXAS HIGH PLAINS
REGION. SOUTH TO SOUTHWEST LOW LEVEL WINDS WILL INCREASE AREAWIDE
TODAY WITH SURFACE GUSTS APPROACHING 25KTS ACROSS EAST TEXAS
THROUGH TONIGHT. WIDELY SCATTERED LIGHT SHOWERS TODAY DUE TO THE
INCREASE IN LIFT AND LOW LEVEL MOISTURE BECOMING MORE NUMEROUS
TONIGHT WITH ISOLATED THUNDERSTORMS POSSIBLE AFTER MIDNIGHT. /14/
&&
.PREV DISCUSSION... /ISSUED 334 AM CST TUE DEC 22 2009/
DISCUSSION...
ACTIVE WEATHER IS IN STORE FOR THE FOUR STATE REGION THIS WEEK AS A
STRONG STORM SYSTEM IS EXPECTED TO AFFECT THE CWFA WEDNESDAY NIGHT
INTO THURSDAY MORNING. SURFACE ANALYSIS THIS MORNING SHOWS HIGH
PRESSURE WELL TO OUR EAST OVER THE FL PANHANDLE...PUTTING THE REGION
UNDER SOUTHERLY WINDS. SATELLITE IMAGERY SHOWS HIGH CLOUDS
INCREASING THIS MORNING AS WELL AS MOISTURE CONTINUES TO INCREASE
OVER THE FOUR STATE REGION.
RETURN FLOW WILL CONTINUE THROUGH THE DAY...BRINGING A CONTINUED
INCREASE IN TEMPERATURES AND MOISTURE. AS A RESULT HAVE MADE A FEW
ADJUSTMENTS TO HIGH TEMPERATURES FOR TODAY. TEMPERATURES YESTERDAY
WERE ABLE TO REACH THE MID 60S FOR MANY LOCATIONS...AND BELIEVE WITH
SOUTHERLY SURFACE FLOW CONTINUING THAT TEMPERATURES TODAY SHOULD BE
COMPARABLE TO YESTERDAY. AS A RESULT...TEMPERATURES FOR MANY
LOCATIONS WERE RAISED FROM MAV GUI. CONTINUED RETURN FLOW WILL ALSO
ALLOW FOR PWATS TO INCREASE TO AROUND AN INCH BY THE MIDDLE OF THE
DAY. THE REGION WILL SEE THE DEVELOPMENT OF ISENTROPIC SHOWERS AS WE
MOVE THROUGH THE DAY...BEGINNING AROUND MID MORNING FOR THE WESTERN
HALF OF THE CWFA. THIS ACTIVITY IS EXPECTED TO INCREASE DURING THE
AFTERNOON AND INTO THE EVENING HOURS...ESPECIALLY OVER THE WESTERN
HALF OF THE CWFA. BY THE OVERNIGHT HOURS MUCH OF THE CWFA SHOULD BE
ABLE TO SEE PERIODS OF RAIN WITH AN OCCASIONAL THUNDERSTORM POSSIBLY
EMBEDDED.
BY WEDNESDAY WE SEE THE MAIN SHORTWAVE BEGIN TO MOVE INTO TX. THIS
WILL BRING AN APPROACHING SURFACE LOW WHICH IS EXPECTED TO MOVE INTO
CENTRAL OK BY WEDNESDAY AFTERNOON. THE LOW WILL REACH E OK/NW AR BY
AROUND MIDNIGHT WEDNESDAY NIGHT/THURSDAY MORNING...WITH A PREFRONTAL
TROUGH SETTING UP OVER EAST TEXAS. DURING THE AFTERNOON AND EVENING
HOURS...ESPECIALLY INTO THE LATE EVENING...THE WESTERN HALF OF THE
CWFA COULD BEGIN TO SEE THE DEVELOPMENT OF STRONG AND SEVERE
THUNDERSTORMS. INSTABILITY WILL BE SOMEWHAT OF A LIMITING FACTOR
WITH MLCAPES EXPECTED TO BE AROUND OR BELOW 1K J/KG. HOWEVER THERE
WILL BE A DECENT UPPER JET APPROACHING WITH DIVERGENCE ALOFT
EXPECTED TO BEGIN OVER THE AREA BY WEDNESDAY AFTERNOON AND
ESPECIALLY INTO WEDNESDAY EVENING. IN ADDITION THE AREA WILL SEE
DECENT LOW LEVEL FLOW WITH 850MB WINDS WEDNESDAY AFTERNOON AND
EVENING EXPECTED TO BE BETWEEN 40-50 KTS. THERE WILL BE ENOUGH SHEAR
AVAILABLE TO SUPPORT STORMS. MOISTURE WILL BE PLENTIFUL WITH PWATS
INCREASING TO AROUND 1.5 INCHES BY WEDNESDAY EVENING. THIS SHOULD
BRING THE POSSIBILITY OF SEEING SOME SEVERE STORMS DEVELOP WEDNESDAY
EVENING...WITH DAMAGING WINDS...HAIL...AS WELL AS A FEW TORNADOES
ALL BEING POSSIBLE. IN ADDITION...THIS ACTIVITY WILL BE CAPABLE OF
PRODUCING HEAVY RAINFALL. THE STRONGEST OF THIS ACTIVITY SHOULD
REMAIN OVER THE WESTERN HALF OF THE CWFA WEDNESDAY AFTERNOON AND
EVENING.
TOWARD LATE WEDNESDAY EVENING AND NEARING MIDNIGHT...A SQUALL LINE
IS EXPECTED TO DEVELOP OVER EAST TEXAS LOCATIONS ALONG THE
PREFRONTAL TROUGH. AS THIS OCCURS THE MAIN CONCERN FOR SEVERE
WEATHER WILL BECOME DAMAGING WINDS AND HEAVY RAINFALL. HOWEVER
HAIL...AND POSSIBLY A TORNADO OR TWO CAN NOT BE RULED OUT. THE
LATEST MODELS ARE HINTING THAT THIS SQUALL LINE WILL BE NEAR OR JUST
EAST OF SHREVEPORT BY AROUND SUNRISE THURSDAY MORNING...AND MOVE
EAST OUT OF THE CWFA BEFORE LUNCHTIME. THEREFORE IT APPEARS THAT IT
WILL BE MOVING THROUGH THE CWFA SOMEWHAT SLOWLY...PRODUCING A DECENT
AMOUNT OF RAINFALL AS IT PASSES THROUGH THE CWFA. MANY LOCATIONS
COULD SEE TWO TO THREE INCHES WEDNESDAY NIGHT INTO THURSDAY
MORNING...WITH ISOLATED HIGHER AMOUNTS POSSIBLE. THIS COULD RESULT
IN FLOODING PROBLEMS FOR PORTIONS OF THE FOUR STATE REGION...AND A
FLASH FLOOD WATCH MAY NEED TO BE CONSIDERED BY LATER SHIFTS.
BY THURSDAY AFTERNOON THINGS SHOULD BE A LITTLE QUIETER FOR THE FOUR
STATE REGION. THERE MAY BE SOME LINGERING LIGHT SHOWERS OVER THE
AREA DURING THE AFTERNOON. THE MAIN SHORTWAVE WILL KICK THE COLD
FRONT THROUGH THE CWFA BY THURSDAY EVENING TO ALLOW ALL SHOWER
ACTIVITY TO END BY THAT TIME.
THE NEXT CONCERN FOR THE FOUR STATE REGION WILL BE COOLER
TEMPERATURES THAT WILL BE MOVING IN BEHIND THIS SYSTEM. A SURFACE
HIGH PRESSURE WILL BE MOVING INTO THE REGION FOR CHRISTMAS DAY AND
THROUGH THE WEEKEND TO KEEP THE AREA DRY. NORTHWEST FLOW WILL
DEVELOP ALOFT AS THE SHORTWAVE PASSES TO THE NORTHEAST OF THE AREA.
THESE SHOULD BRING IN COOLER TEMPERATURES TO THE FOUR STATE REGION.
THIS WILL BRING HIGHS TO THE UPPER 40S AND LOWS AROUND FREEZING TO
POSSIBLY THE UPPER 20S FOR THE HOLIDAY WEEKEND FOR MUCH OF THE FOUR
STATE REGION.
THE UPPER FLOW WILL BECOME MORE ZONAL TOWARD THE BEGINNING OF THE
WORK WEEK...WITH A FEW IMPULSES PASSING THROUGH THE SOUTHERN
STREAM. MODELS THIS MORNING ARE DEVELOPING A SURFACE LOW OVER THE
NORTHERN GULF OF MEXICO FOR THE BEGINNING OF THE WEEK. MODELS ARE
NOT YET IN AGREEMENT WITH THE TIMING OR EXACT POSITION OF THIS LOW
SO IT WILL NEED TO BE MONITORED OVER THE NEXT FEW DAYS. REGARDLESS
IT SHOULD BRING A RETURN OF RAIN CHANCES TO THE FOUR STATE REGION
FOR THE BEGINNING OF NEXT WEEK. /22/
AVIATION...
HIGH CLOUDS QUICKLY INVADING THE REGION FROM THE WEST IN RESPONSE TO
STRONG UPPER LEVEL JET AXIS ACROSS THE SOUTHERN GREAT BASIN. OF MORE
IMPORTANCE IS LOW LEVEL MOISTURE AROUND 4-5KFT STEADILY MOVING
NORTHWARD FROM SE TX. EXPECT THESE CEILINGS TO BE INTO THE
LFK/TYR/GGG TERMINALS NEAR OR BEFORE 10Z WITH CEILINGS LIKELY MAKING
IT INTO THE TXK/SHV TERMINALS NEAR OR SHORTLY AFTER 10Z THIS
MORNING. CROSS SECTIONAL ANALYSIS SUPPORTIVE OF CEILINGS BRIEFLY
STARTING OUT AT VFR NEAR 4KFT WITH THESE CEILINGS GRADUALLY BECOMING
MVFR AND IFR THROUGHOUT THE DAY AS LOW LEVEL MOISTURE INCREASES
ACROSS THE REGION. THIS TREND WAS FOLLOWED WITH THE 06Z TAF SUITE
AND WILL CONTINUE THIS TREND FOR THE 12Z PACKAGE. PRESSURE GRADIENT
CONTINUES TO INCREASE DURING THE DAY INTO THE OVERNIGHT HOURS AS SFC
LOW PRESSURE CONTINUES TO DEEPEN ACROSS THE OK/TX PHNDL REGION.
SOUTH TO SOUTHEAST WINDS WILL INCREASE AREAWIDE TODAY WITH SOME
GUSTS APPROACHING 20KTS ACROSS THE NE TX TERMINALS THIS AFTERNOON
THROUGH TONIGHT.
CANNOT RULE OUT SOME SCATTERED SHOWERS TODAY ACROSS NE TX/SW AR AND
NW LA TERMINALS AS ISENTROPIC LIFT BECOMES QUITE STRONG WITH THE
MOISTURE RETURNING. RAIN CHANCES ARE NOT SIGNIFICANT ENOUGH HOWEVER
TO MENTION ATTM...AT LEAST THROUGH THE DAYTIME HOURS. MAY NEED TO
MAKE MENTION OF SOME SHOWERS BETWEEN 06-12Z TIMEFRAME AT A FEW
LOCATIONS IN NE TX/SW AR. /13/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 65 55 68 54 57 / 30 80 90 100 70
MLU 64 53 65 56 57 / 20 80 90 100 80
DEQ 58 54 64 51 52 / 30 80 90 100 70
TXK 60 54 66 52 56 / 40 80 90 100 70
ELD 63 54 64 56 59 / 20 80 90 100 80
TYR 65 58 68 49 53 / 30 80 90 100 50
GGG 66 58 68 51 56 / 30 80 90 100 50
LFK 70 59 69 52 58 / 30 80 90 100 50
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
&&
$$
05/14
