831
FXUS64 KLCH 172340
AFDLCH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAKE CHARLES LA
640 PM CDT MON AUG 17 2026
..NEW AVIATION
KEY MESSAGES
- A HEAT ADVISORY IS IN EFFECT UNTIL TO 8PM THIS EVENING. TUESDAY,
ANOTHER HEAT ADVISORY HAS BEEN ISSUED FOR ACADIANA BETWEEN 12PM
AND 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 THIS WEEK KEEPING AFTERNOON
HIGHS ABOVE NORMAL.
- NO APPRECIABLE PRECIPITATION CHANCES EXIST THROUGH THE NEXT SEVEN
DAYS.
DISCUSSION
(THIS EVENING THROUGH NEXT SUNDAY)
ISSUED AT 230 PM CDT MON AUG 17 2026
MIDDAY SURFACE ANALYSIS DEPICTS 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 500 MB 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 NOTED A SUBSIDENCE INVERSION AT 900 MB. 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, WHERE OVERALL MOISTURE IS GREATER,
BUT WOULD BE SURPRISED TO SEE ANY MORE THAN A SPRINKLE OF RAINFALL
OUT OF THIS.
THE MAIN CONCERN THROUGH THE SHORT TERM PERIOD WILL BE THE RISK FOR
POTENTIALLY HAZARDOUS HEAT. DESPITE THE NEAR-RECORD HEIGHTS, HEAT
CONCERNS HAVE BEEN PARTIALLY MITIGATED BY DEWPOINTS LOWERING 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 DEEP LAYER MOISTURE IS
GREATER. FOR THIS REASON, A HEAT ADVISORY HAS BEEN ISSUED FOR
CENTRAL AND SOUTH-CENTRAL LOUISIANA 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, 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
(00Z TAFS)
ISSUED AT 638 PM CDT MON AUG 17 2026
VFR CONDITIONS ONGOING AND EXPECTED TO PREVAIL THROUGH THIS TAF
CYCLE WITH MAINLY LIGHT AND VARIABLE WINDS.
MARINE
ISSUED AT 230 PM CDT MON AUG 17 2026
SURFACE HIGH PRESSURE 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. HIGH PRESSURE ALOFT
WILL KEEP RAIN CHANCES 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 230 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 MINIMUM
VALUES WILL RANGE FROM 35 TO 50 PERCENT ACROSS THE AREA THIS WEEK.
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...30
AVIATION...87
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