590
FXUS64 KLCH 221738
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
1238 PM CDT FRI OCT 22 2021
DISCUSSION
FOR 10/22/2021 18Z TAF ISSUANCE.
AVIATION
A WEAK FRONTAL BOUNDARY THAT SLID THROUGH THE REGION OVERNIGHT IS
NOW LARGELY STATIONARY NEAR THE COAST. AS A RESULT, WINDS AT THE
TERMINALS ARE GENERALLY EASTERLY, AND AT TIMES LIGHT AND VARIABLE.
THROUGH THE DAY, SHOULD CONTINUE TO SEE A MIX OF SOME VFR CU
~3500 TO 6000 FT ALONG WITH SOME HIGHER LEVEL CIRRUS FILTERING
THROUGH. GUIDANCE SUGGESTS AN OUTSIDE SHOT AT A WIDELY ISOLATED
SHOWER OR TWO ALONG THE I-10 CORRIDOR THIS AFTERNOON AS THE
BOUNDARY WASHES OUT, BUT COVERAGE IS FAR TOO LOW TO INCLUDE ANY
MENTION IN THE TAFS. BOUNDARY CONTINUES TO WASH OUT OVERNIGHT WITH
SURFACE WINDS BECOMING LIGHT AND VARIABLE TO CALM. CONDITIONS
ONCE AGAIN LOOK FAVORABLE FOR FOG TO DEVELOP AFTER MIDNIGHT GIVEN
THE ABUNDANT LOW LEVEL MOISTURE AND VERY LIGHT LOW LEVEL WINDS.
GUIDANCE SUGGESTS FOG DEVELOPMENT AFTER MIDNIGHT AT
BPT/LCH/LFT/ARA, BECOMING MORE DENSE PRIOR TO SUNRISE. A LITTLE
LESS CONFIDENCE AT AEX, BUT WILL LIKELY SEE SOME VIS REDUCTIONS AS
WELL. AFTER SUNRISE, EXPECT FOG TO GRADUALLY LIFT INTO A BKN MVFR
STRATUS DECK FOR A TIME, WITH WINDS PICKING UP OUT OF THE SSE.
50
PREV DISCUSSION
/ISSUED 1030 AM CDT FRI OCT 22 2021/
UPDATE...
A WEAK SURFACE BOUNDARY HAS WORKED THROUGH THE REGION OVERNIGHT,
STALLING IN THE COASTAL WATERS THIS MORNING. KLCH SHOWING SOME
VERY ISOLATED CONVECTION WITH THIS, WITH GOES-16 VISIBLE ALSO
SHOWING A LINE OF AGITATED CU LIKELY DEMARCATING THE BOUNDARY.
WITH THE BOUNDARY TO THE SOUTH, SOME DRIER AIR HAS MANAGED TO
FILTER INTO CENLA, WITH DEW POINT READINGS IN THE MID 50S. CLOSER
TO THE I-10 CORRIDOR, LOW LEVEL MOISTURE REMAINS QUITE RICH, AND
AS A RESULT DEW POINTS REMAIN CLOSER TO 70. NOT EXPECTING TOO MUCH
DRY AIR TO ADVECT FURTHER SOUTH, AND IF ANYTHING MIGHT SEE THE DEW
POINTS IN CENLA CREEP BACK UP A BIT AS THE STALLED BOUNDARY BEGINS
TO WASH OUT AND WINDS BEGIN TO SHIFT EASTERLY AND THEN BACK TO
SOUTHERLY. NO REAL CAA BEHIND THE AFOREMENTIONED BOUNDARY EITHER,
SO AFTERNOON HIGHS STILL EXPECTED TO BE WELL ABOVE SEASONAL
NORMALS. COMBINATION OF SURFACE HIGH TO OUR NORTH AND 850MB RIDGE
CENTERED ATOP THE REGION WILL HELP KEEP PWATS A BIT MORE IN CHECK,
AND ALSO HELP TO SUPPRESS ALL BUT A FEW WIDELY ISOLATED
THUNDERSHOWERS TODAY. OVERALL, ONLY MADE A FEW MINOR TWEAKS TO THE
INHERITED GRIDS TO ACCOUNT FOR SHORT TERM TRENDS AND GUIDANCE.
50
PREV DISCUSSION... /ISSUED 425 AM CDT FRI OCT 22 2021/
DISCUSSION...
SHORT TERM [TODAY THROUGH SUNDAY NIGHT]...
WX MAP SHOWS WEAK COOL FRONTAL BOUNDARY ACROSS C LA WITH A LIGHT
NORTHEAST WIND AND SLIGHTLY LOWER DEWPOINTS BEHIND THE FRONT. AHEAD
OF THE BOUNDARY LIES CALM WINDS AND AREAS OF DENSE FOG ALONG AND
SOUTH OF THE I-10 CORRIDOR. DENSE FOG ADVISORY REMAINS IN EFFECT
THROUGH 9 AM. LATER THIS AFTERNOON, SLIGHT CHANCE OF SHOWERS AND
PERHAPS A THUNDERSTORM WITH THE WEAK FRONT, STILL QUESTIONABLE IF
IT WILL REACH THE COAST OR STALL ALONG THE I-10 CORRIDOR. CHANCES
REMAIN AT A LOW 20%. WHAT'S CERTAIN IS MUCH ABOVE NORMAL TEMPERATURES
WITH AFTERNOON HIGHS REACHING THE MID TO UPPER 80S. LOWS TONIGHT
IN THE LOWER 60S BEHIND THE FRONT ACROSS C LA/INLAND SE TX, BUT
REMAINING IN THE UPPER 60S TO LOWER 70S FURTHER SOUTH.
FOR SATURDAY, A WEAK SHORTWAVE WITHIN THE ZONAL FLOW ALOFT WILL
LIKELY IMPACT THE REGION GIVING SCATTERED AFTERNOON SHOWERS AND A
FEW THUNDERSTORMS. GIVEN THE MOISTURE AVAILABILITY AND INSTABILITY
WITH AFTERNOON HIGHS IN THE MID TO UPPER 80S ONCE AGAIN, 30-40%
SEAMS REASONABLE. HAD TO LOWER THE NATIONAL BLENDED GUIDANCE WHICH
WAS A BIT TOO HIGH GOING OVER 50%.
SUNDAY, NOT MUCH CHANGE EXPECTED WITH ANOTHER WEAK SHORTWAVE TO
GIVE ISOLATED TO SCATTERED SHOWERS ACROSS THE COASTAL WATERS
DURING THE MORNING, AND DEVELOPING INLAND DURING THE AFTERNOON
HOURS. CHANGES AGAIN 30-40%, AND BELOW THE OVERDONE NATIONAL
BLENDED GUIDANCE. HIGHS ONCE AGAIN IN THE MID TO UPPER 80S.
DML
LONG TERM [MONDAY THROUGH SATURDAY 12Z]...
THE HEAT AND HUMIDITY CONTINUE TO CLIMB AT THE BEGINNING OF THE
FORECAST PERIOD WITH SOUTHERLY WINDS OFF THE GULF OF MEXICO MONDAY
AND TUESDAY. WITH HIGH TEMPERATURES IN THE MID TO UPPER 80S COMBINED
WITH DEWPOINTS IN THE LOW TO MID 70S, THE OUTDOORS WILL FEEL
DOWNRIGHT OPPRESSIVE. CONDITIONS MONDAY AND TUESDAY WILL SUPPORT THE
CHANCE FOR SHWRS AND THUNDERSTORMS, AS GULF MOISTURE AND DAYTIME
RADIATION COULD OFFER AFTERNOON INSTABILITY.
BEYOND TUESDAY, CONFIDENCE MARKEDLY DECREASES AS MODEL GUIDANCE
CONTINUES TO STRUGGLE WITH THE NEXT FRONTAL PASSAGE ACROSS THE US.
AS WE GO FURTHER INTO THE WEEKEND, MODELS WILL HAVE MORE TIME TO
RESOLVE THIS COMING SYSTEM, STAY TUNED AS THE FORECAST WILL UPDATE
WITH LATEST TRENDS. FOR NOW, EURO AS A DEEPER SURFACE LOW SWINGING
THROUGH THE CENTRAL US WITH THE FRONT TRAILING BEHIND IT IN THE FORM
OF A STRONG LINE OF STORMS SWIFTLY MOVING THROUGH ON WEDNESDAY
MORNING/AFTERNOON. THE GFS ON THE OTHER HAND, HAS THE SURFACE LOW
MUCH FURTHER NORTH, RESULTING WITH A SLIGHTLY WEAKER BOUNDARY
PASSING THROUGH THE AREA WHICH WOULD KEEP THE REGION MUCH DRIER ON
WEDNESDAY. AS FOR THE FORECAST, DECIDED TO LEAN INTO THE WETTER
OUTCOME AND KEPT POPS IN THE 40 TO 60 PERCENT RANGE WITH MODEST
RAINFALL TOTALS. FCST PWAT VALUES IN THE 1.50 TO 1.80 INCH RANGE,
ALONG WITH THE FORCING MECHANISM OF THE FRONTAL PASSAGE, RAIN SHOULD
BE EXPECTED.
AFTER WEDNESDAY, GUIDANCE SETTLES IN WITH MINIMAL RAIN CHANCES AS
HIGH PRESSURE TAKES OVER AND NORTHWEST FLOW SPILLS DRY AIR DOWN INTO
THE REGION. AFTER THE FRONT, THURSDAY MORNING COULD SEE TEMPERATURES
IN THE UPPER 50S TO LOW 60S WITH AFTERNOON TEMPERATURES IN THE LOW
80S.
11
AVIATION...
LIFR VISIBILITIES/CEILINGS DUE TO DENSE FOG WILL CONTINUE AT
BPT/LCH/ARA/LFT THROUGH 13-14Z, EXPECTED TO BURN OFF RAPIDLY BY
15Z. FOR AEX, NO SIGNIFICANT RESTRICTIONS EXPECTED AS THE COOL
FRONT HAS MOVED SOUTH OF THIS TERMINAL. LATER THIS MORNING INTO
THE AFTERNOON HOURS, EAST NORTHEAST WINDS AROUND 6-8 KTS EXPECTED,
WITH ONLY ISOLATED SHOWERS POSSIBLE DURING THE AFTERNOON HOURS,
TOO LOW OF A CHANCE TO PUT VCSH IN THE TERMINALS.
DML
MARINE...
THE WEAK SURFACE BOUNDARY EXPECTED TO JUST MAKE IT ACROSS THE
COASTAL WATERS LATER THIS AFTERNOON BEFORE STALLING AND MOVING
BACK NORTH BY SATURDAY. BRIEF OFFSHORE WINDS ACROSS THE NEAR SHORE
WATERS, BUT MOST LIKELY, LIGHT AND VARIABLE ELSEWHERE. WINDS WILL
QUICKLY SHIFT BACK TO AN ONSHORE DIRECTION BY TONIGHT AS THE
FRONT WASHES OUT.
PRELIMINARY POINT TEMPS/POPS
AEX 61 86 64 86 / 10 20 10 30
LCH 68 84 70 84 / 10 40 10 40
LFT 68 85 69 86 / 20 20 10 40
BPT 69 84 71 84 / 10 40 20 40
LCH WATCHES/WARNINGS/ADVISORIES
LA...NONE.
TX...NONE.
GM...NONE.
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