836
FXUS64 KLCH 161119
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
619 AM CDT WED SEP 16 2026
..NEW AVIATION
KEY MESSAGES
- A PASSING UPPER LEVEL DISTURBANCE WILL BRING LOW END RAIN
CHANCES (20-30 PERCENT) TO LOWER ACADIANA AND COASTAL AREAS
WEDNESDAY.
- DRIER AIR WILL MOVE INTO THE REGION, THURSDAY AND FRIDAY WHICH
WILL LOWER HEAT INDICES AND MAKE CONDITIONS FEEL MORE
COMFORTABLE.
- PRECIPITATION CHANCES INCREASE SUNDAY INTO EARLY NEXT WEEK, AS
AN AREA OF LOW PRESSURE MOVES INTO THE NORTHEASTERN GULF.
DISCUSSION
(TODAY THROUGH TUESDAY)
ISSUED AT 1223 AM CDT WED SEP 16 2026
THE LARGE SCALE UPPER LEVEL PATTERN TONIGHT IS DOMINATED BY AN
EXPANSIVE RIDGE OF HIGH PRESSURE CENTERED OVER THE SOUTHERN
APPALACHIANS, WITH OUR CWA LOCATED ON THE SOUTHWESTERN PERIPHERY OF
THIS RIDGE. AT THE SURFACE, A RIDGE OF HIGH PRESSURE CENTERED ALONG
THE ATLANTIC EASTERN SEABOARD IS BRINGING LIGHT, GENERALLY SOUTHERLY
SURFACE FLOW TO OUR AREA. DEEP TROPICAL MOISTURE REMAINS IN PLACE,
WITH THE KLCH 00Z SOUNDING MEASURING A PWAT OF 2.38 INCHES, NEARLY A
DAILY MAXIMUM AND WELL IN EXCESS OF THE 90TH PERCENTILE FOR THE DATE
PER SPC SOUNDING CLIMATOLOGY. WITH THIS DEEP MOISTURE IN PLACE AND
CLEAR SKIES EXPECTED OVERNIGHT, SOME PATCHY FOG MAY DEVELOP TONIGHT
AS IT HAS THE PAST SEVERAL NIGHTS. THIS WOULD BE MOST LIKELY TO
OCCUR IN INLAND AREAS THAT SAW RAINFALL TODAY. ANY FOG IS NOT
EXPECTED TO BE DENSE AND WILL DISSIPATE WITH SUNRISE.
THE UPPER-LEVEL RIDGE IS EXPECTED TO RETROGRADE AND BUILD OVER THE
MISSISSIPPI VALLEY WEDNESDAY. THE STRENGTH OF THIS RIDGE IS
IMPRESSIVE, WITH LREF MEAN 500 MB HEIGHTS IN EXCESS OF 99TH
PERCENTILE ACROSS A VAST SWATH OF THE SOUTHERN US THAT INCLUDES ALL
OF OUR CWA. DESPITE THIS, AN UPPER-LEVEL INVERTED SHORTWAVE
DISTURBANCE WILL TRANSIT THE NORTHERN GULF COAST FROM EAST TO WEST
TOMORROW, AND WILL COME WITH A PUSH OF ENHANCED DEEP LAYER MOISTURE.
SCATTERED AFTERNOON CONVECTION IS EXPECTED TO DEVELOP, BUT COVERAGE
AND INTENSITY IS LIKELY TO BE LIMITED BY LARGE-SCALE SUBSIDENCE AS
WELL AS MID-LEVEL WARMING DUE TO THE EXPANDING RIDGE. HIGHEST
CHANCES FOR STORMS WILL BE IN LOWER ACADIANA AND ALONG THE GULF
COASTLINE, IN CLOSER PROXIMITY TO THE UPPER DISTURBANCE AND FARTHER
FROM THE INFLUENCE OF THE RIDGE.
AS THE DISTURBANCE EXITS, THE UPPER-LEVEL RIDGE CONTINUES TO MIGRATE
WEST TOWARDS THE ARKLATEX REGION WHILE SURFACE HIGH PRESSURE BUILDS
INTO THE SOUTH. THIS WILL SET UP A LARGE-SCALE EASTERLY TO
NORTHEASTERLY FLOW PATTERN THAT WILL ADVECT NOTICEABLY DRIER AIR
INTO THE ENTIRE COLUMN STARTING THURSDAY INTO THE END OF THE WEEK.
LREF MEAN PWATS FALL TO 1.1-1.2 INCHES (CLIMATOLOGICAL 20TH
PERCENTILE), WHILE SURFACE DEWPOINTS SHOULD FALL INTO THE 60S AREA-
WIDE EXCEPT PERHAPS FOR IMMEDIATE COASTAL SITES. SOME INLAND
LOCATIONS MAY EVEN BE LUCKY ENOUGH TO SEE DEWPOINTS FALL INTO THE
50S, PARTICULARLY FRIDAY AFTERNOON. WHILE AFTERNOON MAX TEMPERATURES
ARE NOT EXPECTED TO CHANGE MUCH, THE DRIER AIR WILL BRING A
NOTICEABLE DROP IN HEAT INDEX VALUES, AS WELL AS KEEP RAIN CHANCES
ESSENTIALLY ZERO THROUGH SATURDAY.
THE FORECAST THEN BECOMES A BIT MORE UNCERTAIN AS AN UPPER-LEVEL LOW
DETACHES FROM A TROUGH CURRENTLY OFF THE ATLANTIC EAST COAST AND
ROTATES INTO THE FLORIDA PENINSULA AND NORTHEAST GULF EARLY THIS
WEEKEND. GUIDANCE DIVERGES ON THE STRENGTH, TRACK, AND SPEED OF THIS
LOW, WITH THE EURO AND ITS ENSEMBLE GENERALLY SLOWER AND FURTHER
EAST THAN THE GFS/GEFS SOLUTIONS. REGARDLESS, A PUSH OF MOISTURE IS
EXPECTED WITH THIS FEATURE WITH DEWPOINTS LIKELY RISING BACK INTO
THE 70S AREA-WIDE. WITH THE ADDED MOISTURE WILL COME A GRADUAL
RETURN OF RAIN CHANCES, FIRST FOR LOWER ACADIANA AND GRADUALLY
SPREADING ACROSS THE REMAINDER OF THE CWA TO START NEXT WEEK.
64/SILAS
AVIATION
(12Z TAFS)
ISSUED AT 617 AM CDT WED SEP 16 2026
IT WILL BE A BATTLE TODAY BETWEEN DRIER AIR MOVING IN WITH A
BUILDING UPPER HIGH FROM THE NORTH WITH A WAVE MOVING ACROSS THE
NORTHERN GULF. IT LOOKS LIKE THE DRIER AIR ALOFT WILL WIN OUT SO
WILL NOT MENTION ANY CONVECTION AT TERMINALS WITH VFR CONDITIONS.
07/RUA
MARINE
ISSUED AT 1223 AM CDT WED SEP 16 2026
A PASSING UPPER DISTURBANCE WILL BRING SCATTERED SHOWERS AND
THUNDERSTORMS TO GULF WATERS FOR WEDNESDAY THROUGH EARLY THURSDAY
MORNING. INITIALLY LIGHT SOUTHEAST WINDS WILL BEGIN TO SHIFT MORE
EASTERLY AS HIGH PRESSURE BUILDS INTO THE SOUTHEAST CONUS. THE
TIGHTENED PRESSURE GRADIENT WILL CAUSE WINDS TO RAMP UP STARTING
WEDNESDAY AFTERNOON, WITH EAST WINDS GUSTING TO 25+ KT POSSIBLE
ALONG WITH SEAS TO 6 FT. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR
ALL OPEN GULF WATERS THROUGH THURSDAY EVENING, AND WILL LIKELY NEED
TO BE EXTENDED FURTHER PARTICULARLY FOR EASTERN ZONES.
FIRE WEATHER
ISSUED AT 1223 AM CDT WED SEP 16 2026
A DEEP TROPICAL AIRMASS REMAINS IN PLACE OVER THE AREA, WITH
ISOLATED SHOWERS AND THUNDERSTORMS EXPECTED FOR COASTAL AREAS
WEDNESDAY AFTERNOON. A MUCH DRIER AIRMASS MOVES IN FOR THURSDAY INTO
THE WEEKEND, WITH RAIN CHANCES NEAR ZERO AREA-WIDE. AFTERNOON MINRH
VALUES WILL DECREASE TO 30-40 PERCENT INLAND AND 45-55 PERCENT NEAR
THE COAST THROUGH THIS PERIOD, WITH 5-10 KT WINDS OUT OF THE EAST OR
NORTHEAST.
LCH WATCHES/WARNINGS/ADVISORIES
LA...NONE.
TX...NONE.
GM...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 7 PM CDT
THURSDAY FOR GMZ450-452-455-470-472-475.
PUBLIC/FIRE/MARINE...64
AVIATION...07
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