353
FXUS64 KSHV 231744
AFDSHV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SHREVEPORT LA
1244 PM CDT TUE JUL 23 2019
AVIATION
BACK EDGE OF POST FRONTAL CLOUDS ACROSS EXTREME SOUTHERN SECTIONS
OF CWA, AND JUST MOVG SOUTH OF KLFK. ISOLD FAIR WX CUMULUS FILLING
IN ACROSS REMAINING PORTIONS OF AREA. NE WINDS 10 TO 15 KTS THIS
AFTN WITH HIGHER GUSTS POSSIBLE, MAINLY KSHV AND KMLU. WINDS BACK
DOWN EITHER SIDE OF 5 KTS BY 24/00Z AND WILL INCREASE TO EITHER
SIDE OF 10 KTS BY AROUND 24/15Z WITH DAYTIME MIXING UNDER
CONTINUED VFR SKC./07/.
PREV DISCUSSION
/ISSUED 1023 AM CDT TUE JUL 23 2019/
UPDATE...
CLOUD FREE CLEARING LINE IS NOW SOUTH OF I-20, EXCEPT JUST
CROSSING THE INTERSTATE NEAR MLU. NE WINDS 10 TO 15 MPH WITH
PRESSURE GRADIENT AND WIND SPEEDS GRADUALLY DECREASING FROM THE
NORTH THIS AFTN. A FEW LIGHT SHOWERS LINGERING OVER SE CORNER OF
AREA AND WILL RESEND ZONES AT 1 PM TO REMOVE WORDING OF THESE
ISOLD SHOWERS. WILL ALSO MAKE SURE TEMPS STILL ON TRENDS TO REMAIN
IN MIDDLE TO UPPER 80'S AREAWIDE./07/.
PREV DISCUSSION... /ISSUED 320 AM CDT TUE JUL 23 2019/
SHORT TERM.../TODAY THROUGH WEDNESDAY/
PREFRONTAL TROUGH HAS PUSHED THROUGH OUR ENTIRE REGION WITH THE
TRUE COLD FRONT CURRENTLY PUSHING THROUGH OUR SOUTHERN ZONES
ATTM. SHOWERS HAVE BEEN SPOTTY AT BEST AND MAINLY CONFINED TO OUR
EASTERN THIRD EARLY THIS MORNING DESPITE HIGH RES PROGS SUGGESTING
WE COULD STILL SEE SOME POST FRONTAL CONVECTION ALONG AND SOUTH
OF THE I-20 CORRIDOR OF N LA CLOSER TO SUNRISE. THE 850MB TROUGH
AXIS LAGS THE SFC FRONTAL BOUNDARY ABOUT A HUNDRED MILES OR SO TO
THE NORTH AND UNTIL WE GET THAT FEATURE THROUGH OUR REGION, WILL
CONTINUE TO CARRY SLIGHT CHANCE POPS AS FAR NORTH AS THE I-20
CORRIDOR WITH A PRE-FIRST PERIOD POP, TAPERING POPS UPWARD TO MID
CHANCE CATEGORIES FURTHER SOUTH ENCOMPASSING DEEP EAST TEXAS AS
WELL AS WEST CENTRAL AND EAST CENTRAL LOUISIANA THROUGH MID
MORNING.
OTHERWISE, MUCH DRIER AIR WILL CONTINUE TO BLEED INTO THE REGION
FROM THE NORTH AND EAST TODAY WITH A NOTICEABLE DIFFERENCE IN
TEMPERATURES AND HUMIDITY LEVELS, QUITE A SURPRISE FOR LATE JULY.
DID NOT STRAY TOO FAR FROM MOS OUTPUT CONCERNING TEMPERATURES
TODAY WITH HIGHS RANGING MOSTLY IN THE MIDDLE TO UPPER 80S.
OVERNIGHT, SFC RIDGE AXIS WILL REMAIN WELL TO OUR NORTH AND WEST
AND WHILE WINDS WILL DECOUPLE THIS EVENING, THEY WILL NOT GO CALM
WHICH SHOULD NOT ALLOW LOWS FROM FALLING AS COOL AS THEY COULD.
HAVING SAID THAT, STILL EXPECTING LOWS TO FALL INTO THE LOWER TO
MIDDLE 60S AREAWIDE WITH UPPER 50S POSSIBLE ACROSS THE MORE
PROTECTED AREAS OF SE OK AND SW AR.
NORTHERLY FLOW ALOFT AND NORTHEASTERLY FLOW AT THE SFC WILL KEEP
THE MILDER AIRMASS IN PLACE ON WEDNESDAY WITH MIDDLE TO UPPER 80S
ONCE AGAIN BY AFTERNOON AND ANOTHER DAY OF PLEASANT AFTERNOON
HUMIDITY LEVELS.
13
LONG TERM.../WEDNESDAY NIGHT THROUGH MONDAY NIGHT/
A GRADUAL WARMING TREND WILL COMMENCE THURSDAY THROUGH THE UPCOMING
WEEKEND AS A MORE ERLY LOW LEVEL FLOW SETS UP S OF THE MIDWEST SFC
RIDGE, ONCE IT BEGINS TO DRIFT E INTO THE OH VALLEY. HOWEVER,
ABNORMALLY LOW RH'S WILL PERSIST WEDNESDAY NIGHT THROUGH FRIDAY AS
THE GULF INFLOW WILL REMAIN SHUT OFF. HAVE AGAIN TRENDED MAX TEMPS
CLOSER TO THE SLIGHTLY WARMER BLENDS/MOS GUIDANCE THAN THE COOLER
NBM NUMBERS, GIVEN THE STRONG INSOLATION EXPECTED AND ONLY A MINIMAL
DIURNAL CU FIELD EXPECTED TO DEVELOP THURSDAY AND FRIDAY. BELOW
NORMAL AND COMFORTABLE MIN TEMPS LOOK TO PERSIST THROUGH FRIDAY
NIGHT BEFORE THE AIR MASS BEGINS TO SIGNIFICANTLY MODIFY.
THE UPPER LEVEL FLOW WILL BEGIN TO CHANGE THOUGH BY FRIDAY AS THE
GFS/ECMWF CONTINUE TO DEVELOP A WEAK LOW/SHEAR AXIS THURSDAY
NIGHT/FRIDAY OVER THE LOWER MS VALLEY, AROUND THE ERN PERIPHERY OF
THE FOUR CORNERS RIDGE. THIS SHEAR AXIS REMAINS PROGGED TO BACKBUILD
SW INTO SW LA/SCNTRL LA/THE EXTREME SE TX COAST/NW GULF FRIDAY, THUS
FOCUSING ISOLATED CONVECTION FRIDAY AFTERNOON OVER THESE AREAS.
HOWEVER, THE SE LOW LEVEL FLOW SHOULD RETURN TO THE REGION FRIDAY
NIGHT/SATURDAY ALLOWING FOR GRADUAL BNDRY LYR MODIFICATION, WITH THE
INCREASE IN RH'S QUITE APPARENT BY SATURDAY. THIS WEAK SHEAR AXIS
STILL APPEARS AS IF IT MAY DRIFT N/WOBBLE A BIT SATURDAY SUCH THAT
ISOLATED TO WIDELY SCT CONVECTION MAY DEVELOP FARTHER N ACROSS DEEP
E TX/NCNTRL LA, AND THUS HAVE MAINTAINED LOW CHANCE POPS ACROSS THE
FAR SRN TIER OF COUNTIES/PARISHES AND SLIGHT CHANCE POPS FARTHER N
TO JUST S OF THE I-20 CORRIDOR OF E TX/N LA. HAVE ALSO TRENDED MAX
TEMPS BACK CLOSER TO THE SEASONAL NORMS FOR NEXT WEEKEND WITH THE
INCREASING RH'S. SIMILAR CONDITIONS ARE EXPECTED SUNDAY WITH THE
SHEAR AXIS LINGERING FROM THE TN VALLEY SW ACROSS THE LOWER MS
VALLEY/SE TX, ALTHOUGH THE POTENTIAL FOR WIDELY SCT CONVECTION MAY
SPREAD A BIT FARTHER N INTO SCNTRL AR/NW LA AND ADJACENT AREAS OF
LOWER E TX. THUS, LOW CHANCE POPS WERE ADJUSTED N A BIT OVER THESE
AREAS, WITH SLIGHT CHANCE POPS FARTHER N ACROSS NE TX/SE OK/SW AR
WHICH SHOULD BE UNDER THE INFLUENCE OF THE PLAINS UPPER RIDGING, AND
APPEARS TO EXPAND E ACROSS THE OZARKS TOWARDS THE MID-SOUTH REGION.
WITH THIS RIDGE EXPANSION, THE MEDIUM RANGE PROGS SUGGEST THAT THE
RESIDUAL SHEAR AXIS WILL BEGIN SHIFTING SE INTO THE NRN GULF/SE
LA/CNTRL AND SRN MS MONDAY, AND THUS HAVE MAINTAINED SLIGHT CHANCE
POPS AREAWIDE TO ACCOUNT FOR ANY LINGERING WEAKNESS ALOFT ALONG THE
ERN SIDE OF THE RIDGE.
BOTH THE 00Z ECMWF AND GFS SUGGEST A WEAK UPPER TROUGH WILL SLIDE SE
INTO THE REGION MONDAY NIGHT/TUESDAY, WHICH MAY ALLOW FOR A WEAK SFC
FRONT TO MIX SE ACROSS ACROSS PORTIONS OF AR/N LA. WHILE THIS IS
CURRENTLY PROGGED TO OCCUR JUST BEYOND THE END OF THE EXTENDED
PERIOD, THE UPPER TROUGH AND ASSOCIATED FRONT LOOKS TO BE MUCH
WEAKER THAN THE CURRENT TROUGH/FRONT SWEEPING THROUGH THE REGION
THIS MORNING. HOWEVER, LARGE SCALE FORCING MAY BE GREAT ENOUGH FOR
AN INCREASE IN SCT CONVECTION AT LEAST OVER THE NRN HALF OF THE AREA
EARLY NEXT WEEK.
15
PRELIMINARY POINT TEMPS/POPS
SHV 87 64 87 65 / 10 0 0 0
MLU 84 62 86 64 / 20 0 0 0
DEQ 87 59 87 61 / 0 0 0 0
TXK 85 62 85 63 / 0 0 0 0
ELD 84 59 86 62 / 0 0 0 0
TYR 86 64 87 65 / 0 0 0 0
GGG 86 63 86 64 / 10 0 0 0
LFK 88 64 88 64 / 30 0 0 0
SHV WATCHES/WARNINGS/ADVISORIES
AR...NONE.
LA...NONE.
OK...NONE.
TX...NONE.
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