760
FXUS64 KLCH 171935
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
235 PM CDT MON AUG 17 2026
..NEW DISCUSSION, MARINE, FIRE WEATHER
KEY MESSAGES
- A HEAT ADVISORY IS IN EFFECT FROM 11 AM TO 8PM. HIGHS IN THE
MID 90S TO 100F AND HUMIDITY WILL RESULT IN HEAT INDICES IN THE
105 TO 111F RANGE.
- AN UPPER LEVEL RIDGE WILL REMAIN IN PLACE ACROSS THE NORTHERN
GULF COAST THROUGH THE MIDDLE OF NEXT WEEK KEEPING AFTERNOON
HIGHS ABOVE NORMAL.
- PRECIPITATION CHANCES REMAIN NEAR ZERO THROUGH THE WORKWEEK.
SOME ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS MAY RETURN TO
EASTERN PORTIONS OF THE AREA BY THE WEEKEND, THOUGH CONFIDENCE
IS LOW AT THIS TIME.
DISCUSSION
(THIS EVENING THROUGH NEXT SUNDAY)
ISSUED AT 226 PM CDT MON AUG 17 2026
MIDDAY SURFACE ANALYSIS SHOWS A HIGH PRESSURE SYSTEM CENTERED OVER
THE NORTHERN GULF, RESULTING IN LIGHT WINDS ACROSS THE AREA
GENERALLY OUT OF THE SOUTHWEST. THE LARGE-SCALE UPPER LEVEL PATTERN
IS DOMINATED BY A SPRAWLING RIDGE OVER THE SOUTHERN TIER OF THE
CONUS. THE 18Z KLCH RAOB MEASURED A 500 MB HEIGHT OF 596 DAM, WHICH
IS 99TH PERCENTILE COMPARED TO LOCAL CLIMATOLOGY FOR MID-AUGUST, AND
ALSO DEPICTED A SUBSIDENCE INVERSION AT 900 MB. A GRADIENT IN TOTAL
COLUMN MOISTURE IS NOTED ACROSS OUR CWA TODAY, WITH GOES DERIVED
BLENDED PWAT RANGING FROM 1.4-1.5 INCHES OVER SOUTHEAST TEXAS TO
1.9-2.0 INCHES OVER LOWER ACADIANA AND THE ATCHAFALAYA BASIN. THIS
SUBSIDENT ENVIRONMENT HAS RESULTED IN MOST OF THE AREA BEING
DEVOID OF ANY CLOUD COVER AT ALL. SOME CUMULUS IS NOTED ALONG THE
SEA BREEZE AND OVER LOWER ACADIANA, BUT WOULD BE VERY SURPRISED
TO SEE ANY MORE THAN A SPRINKLE OF RAINFALL IN THESE AREAS (IF
ANYTHING AT ALL).
THE MAIN CONCERN THROUGH THE SHORT TERM PERIOD WILL BE THE RISK FOR
POTENTIALLY HAZARDOUS HEAT. DESPITE THE NEAR-RECORD UPPER-LEVEL
HEIGHTS, HEAT CONCERNS HAVE BEEN PARTIALLY MITIGATED BY LOWERING
DEWPOINTS WITH AFTERNOON MIXING, AND THAT IS EXPECTED TO BE THE CASE
FOR THE NEXT SEVERAL DAYS AS WELL. THAT SAID, DOWNWARD MIXING OF
DRIER AIR WILL BE LESS EFFICIENT FURTHER EAST, WHERE MORE DEEP LAYER
MOISTURE IS PRESENT. FOR THIS REASON, A HEAT ADVISORY HAS BEEN
ISSUED FOR AREAS GENERALLY ALONG AND EAST OF THE I-49 CORRIDOR FOR
TOMORROW, WHERE HEAT INDICES MAY REACH UP TO 109-110 DEGREES.
CONFIDENCE IN REACHING ADVISORY CRITERIA IS LOWER FOR THE REMAINDER
OF THE CWA, SO THESE AREAS HAVE BEEN LEFT OUT OF THE HEAT ADVISORY
FOR NOW. EVENING SHIFT WILL REASSESS FOR ANY CHANGES TO THE HEAT
HEADLINES TONIGHT WITH UPDATED GUIDANCE.
THIS PATTERN WILL PERSIST THROUGH MIDWEEK, WITH RIDGING KEEPING
TEMPERATURES HOT WITH LITTLE TO NO CHANCE OF RAINFALL. CURRENT
THINKING IS THAT A GENERAL DRYING TREND SHOULD KEEP HEAT INDICES
BELOW CRITERIA AFTER TOMORROW, BUT CONFIDENCE IN THE EVOLUTION OF
LOW-LEVEL MOISTURE IS LOW. REGARDLESS OF WHETHER ANY HEAT HEADLINES
ARE IN EFFECT, HEAT SAFETY PRACTICES ARE STRONGLY RECOMMENDED
PARTICULARLY FOR THOSE WHO ARE MORE SENSITIVE TO HIGH TEMPERATURES.
AFTER MIDWEEK, THE UPPER LEVEL RIDGE WILL BUILD OVER THE FOUR
CORNERS STATES WHILE A TROUGH DIGS SOUTHWARD INTO THE MISSISSIPPI
AND OHIO VALLEYS, HELPING ERODE THE RIDGE TO OUR NORTHEAST. THIS
WILL ALLOW A FEW DEGREES OF COOLING FOR OUR AREA, THOUGH IT WILL
STILL BE HOT, WITH AFTERNOON HIGHS LOOKING GENERALLY IN THE LOW TO
MID 90S. THIS PATTERN SHIFT WOULD ALSO ALLOW ISOLATED AFTERNOON
CONVECTION TO MAKE A RETURN TO THE FORECAST AREA BY THE END OF THE
WEEK, WITH GREATER CHANCES OVER THE EASTERN PORTIONS OF OUR AREA
FURTHER REMOVED FROM THE UPPER-LEVEL RIDGE.
64/SILAS
AVIATION
(18Z TAFS)
ISSUED AT 1239 PM CDT MON AUG 17 2026
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. A FEW SHOWERS
AND EVEN AN ISOLATED THUNDERSTORM MIGHT DEVELOP THIS AFTERNOON
ALONG THE SEA BREEZE BOUNDARY IN ACADIANA BRIEFLY IMPACTING KLFT
AND KARA. WINDS ARE MAINLY LIGHT AND VARIABLE BELOW 10 KT.
MARINE
ISSUED AT 226 PM CDT MON AUG 17 2026
SURFACE HIGH PRESURE OVER THE NORTHWEST GULF WILL KEEP WINDS LIGHT
OUT OF THE SOUTHWEST THROUGH THE FORECAST PERIOD, GENERALLY NO MORE
THAN 5-12 KT, WITH SEAS AROUND 1-2 FT. WITH STRONG HIGH PRESSURE
ALOFT, RAIN CHANCES WILL BE NEAR ZERO THROUGH MUCH OF THE WEEK.
SOME ISOLATED SHOWER ACTIVITY MAY RETURN BY THIS WEEKEND, WITH
GREATER CHANCES FURTHER EAST.
FIRE WEATHER
ISSUED AT 226 PM CDT MON AUG 17 2026
HOT CONDITIONS ARE EXPECTED ACROSS THE CWA THROUGH THE FORECAST
PERIOD, WITH POPS NEARLY ZERO THROUGH MIDWEEK. DAILY RH MINIMA
WILL RANGE FROM 35 TO 50 PERCENT ACROSS THE AREA, WITH LOWER
VALUES FURTHER NORTH. SURFACE HIGH PRESSURE OVER THE NORTHERN GULF
WILL KEEP WINDS LIGHT OUT OF THE SOUTHWEST THROUGH THE PERIOD.
LCH WATCHES/WARNINGS/ADVISORIES
LA...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR LAZ027>033-044-045-
055-073-074-141>143-152>154-241>243-252>254.
HEAT ADVISORY FROM NOON TO 8 PM CDT TUESDAY FOR LAZ028-029-032-
033-044-045-055-143-152>154-243-252>254.
TX...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR TXZ180-201-259>262-
515-516-615-616.
GM...NONE.
PUBLIC/FIRE/MARINE...64
AVIATION...05
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