043
FXUS63 KLSX 122259
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
559 PM CDT FRI SEP 12 2025
KEY MESSAGES
-ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH AT LEAST WEDNESDAY.
-DAILY CHANCES FOR SPOTTY AFTERNOON SHOWERS AND THUNDERSTORMS
STARTS SATURDAY AND EXTENDS THROUGH AT LEAST WEDNESDAY.
SHORT TERM
(THROUGH LATE SATURDAY NIGHT)
ISSUED AT 211 PM CDT FRI SEP 12 2025
AS OF 2PM TEMPERATURES HAVE WARMED INTO THE UPPER 80S TO LOW 90S
AREAWIDE UNDER THE INFLUENCE OF A BUILDING MID-LEVEL RIDGE, LOW-
LEVEL WARM AIR ADVECTION, AND ABUNDANT SUNSHINE. A SHORTWAVE
DISTURBANCE IS EXPECTED TO MOVE ALONG THE NORTHERN PERIPHERY OF
THE RIDGE THIS EVENING, AND WHILE THE WEAK FORCING AND DRY LOW
LEVEL AIR WILL LARGELY MITIGATE ANY RAINFALL, I CANNOT RULE OUT A
FEW SPRINKLES ACROSS NORTHEAST MISSOURI AND WEST-CENTRAL ILLINOIS.
BY SATURDAY THE MID-LEVEL RIDGE WILL BE SQUARELY OVER THE MID-
MISSISSIPPI VALLEY, WITH 850 MB TEMPERATURES PUSHING ABOVE THE 90TH
CLIMATOLOGICAL PERCENTILE FOR THIS TIME OF YEAR. COMBINED WITH
PLENTY OF SUNSHINE, THIS WILL RESULT IN ONE OF THE HOTTEST DAYS OF
THE PERIOD WITH HIGHS PUSHING THE MID TO UPPER 90S. INSTABILITY WILL
BE ABLE TO FORM UNDERNEATH THE RIDGE, WITH THE HREF IS DEPICTING
UP TO 1000-1500 J/KG OF MUCAPE DURING THE AFTERNOON. WITHIN THE
LOW-LEVEL WARM AIR ADVECTION REGIME, CONVECTIVE INHIBITION WILL
BE AT A MINIMUM, PARTICULARLY DURING THE AFTERNOON. COMBINED WITH
STEEP LOW-LEVEL LAPSE RATES, WIDELY ISOLATED SHOWERS AND
THUNDERSTORMS ARE POSSIBLE DURING THE AFTERNOON SATURDAY, DESPITE
THE BUILDING MID-LEVEL RIDGE.
DELIA
LONG TERM
(SUNDAY THROUGH NEXT FRIDAY)
ISSUED AT 211 PM CDT FRI SEP 12 2025
SUNDAY THROUGH WEDNESDAY OF NEXT WEEK WILL FEEL LIKE NEARLY A CARBON
COPY OF SATURDAY AS THE MID-LEVEL RIDGE PERSISTS ACROSS THE CENTRAL
CONUS AS A PART OF AN OMEGA BLOCK. SUNDAY'S TEMPERATURES WILL PEAK
ONCE AGAIN IN THE MID TO UPPER 90S AREAWIDE, A LITTLE WARMER THAN 24
HOURS AGO AS THE SIGNAL FOR HIGH CLOUDS HAS DISSIPATED. THE MID-
LEVEL RIDGE WILL SHIFT EASTWARD OVER THE WEEK, AND HIGH TEMPERATURES
WILL COOL A FEW DEGREES BUT REMAIN IN THE 90S THROUGH AT LEAST
WEDNESDAY. EACH DAY ISOLATED AFTERNOON SHOWERS AND PERHAPS A
THUNDERSTORM WILL DEVELOP ACROSS THE REGION. WHILE THE LOCATION OF
WHERE THIS RAIN FORMS IS UNCERTAIN, CONFIDENCE IS HIGH THAT AMOUNTS
WILL NOT BE ENOUGH TO MAKE A SIGNIFICANT IMPACT IN THE HOT AND DRY
CONDITIONS GRIPPING THE REGION.
AS THE MID-LEVEL RIDGE TIPS TO THE NORTHEAST BY MID-WEEK, A MID-
LEVEL TROUGH WILL SLIDE INTO THE UPPER PLAINS, HELPING TO BREAK THE
OMEGA BLOCK. THE EVOLUTION OF THIS FEATURE AND ITS IMPACTS REMAIN
UNCERTAIN, THOUGH ALL GLOBAL ENSEMBLE MEMBERS DEPICT THE TROUGH. THE
INTERQUARTILE SPREAD FOR HIGH TEMPERATURES DEPICTS A CLEAR COOLING
TREND FOR THE END OF NEXT WEEK AND NEXT WEEKEND, THE DETAILS OF
WHICH ARE WRAPPED UP IN THE UNCERTAINTY OF THE TROUGH.
DELIA
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 558 PM CDT FRI SEP 12 2025
CONFIDENCE IS HIGH IN DRY AND VFR FLIGHT CONDITIONS THROUGH THE
TAF PERIOD AT ALL LOCAL TERMINALS.
ELMORE
CLIMATE
ISSUED AT 218 PM CDT WED SEP 10 2025
RECORD DAILY HIGHS FRIDAY 9/12 THROUGH MONDAY 9/15:
9/12 | 9/13 | 9/14 | 9/15
STL 98 100 101 101
COU 100 99 104 101
UIN 99 100 99 100
DELIA
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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