807
FXUS63 KLSX 120838
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
338 AM CDT FRI SEP 12 2025
KEY MESSAGES
- SEASONALLY HOT TEMPERATURES WILL CONTINUE THROUGH AT LEAST THE MIDDLE
OF NEXT WEEK. THE HOTTEST TEMPERATURES ARE EXPECTED THIS
WEEKEND.
- THERE IS A SLIGHT CHANCE (10 - 20%) OF SHOWERS AND THUNDERSTORMS EACH
DAY FROM SUNDAY THROUGH WEDNESDAY.
SHORT TERM
(THROUGH LATE SATURDAY AFTERNOON)
ISSUED AT 337 AM CDT FRI SEP 12 2025
CONTINUED MID-LEVEL RIDGING, PLENTY OF SUN, AND WARM AIR ADVECTION
ALONG LOW-LEVEL SOUTHWEST WINDS WILL BOOST TEMPERATURES INTO THE LOW
TO MID-90S THIS AFTERNOON. TOMORROW, THE RIDGE WILL BE ALMOST
DIRECTLY OVERHEAD AND 850 MB TEMPERATURES WILL CLIMB INTO THE LOW
20S C, TRANSLATING TO MID-90S AT THE SURFACE. THANKFULLY, THE LACK
OF HIGH HUMIDITY WILL KEEP HEAT INDEX VALUES WITHIN A COUPLE OF
DEGREES OF THE ACTUAL TEMPERATURE, MAKING TRIPLE DIGIT HEAT INDEX
VALUES AN UNCOMMON OCCURRENCE ACROSS THE AREA.
JAJA
LONG TERM
(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 337 AM CDT FRI SEP 12 2025
ON SUNDAY THE MID-LEVEL RIDGE AXIS WILL BE DIRECTLY OVERHEAD WITH
TROUGHING OVER THE CENTRAL AND NORTHERN PLAINS. THE TEMPERATURE
FORECAST WILL BE ON PAR WITH SATURDAY, THOUGH THERE WILL BE A SLIGHT
GRADIENT INCREASING FROM WEST TO EAST DUE TO INCOMING HIGH CLOUDS.
THE CONTINUED INFLUENCE OF THE RIDGE WILL KEEP TEMPERATURES IN THE
90S THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. THIS IS CORROBORATED
BY A TIGHT NBM INTERQUARTILE TEMPERATURE SPREAD OF 2 - 3 DEGREES
EACH DAY.
THERE IS A SLIGHT CHANCE (10 - 20%) OF DIURNALLY DRIVEN ISOLATED
SHOWERS AND THUNDERSTORMS FROM SUNDAY THROUGH WEDNESDAY AS
INSTABILITY INCREASES. THE MID-LEVELS WON'T SEE THE SAME DEGREE OF
WARMING AS THE LOW-LEVELS. THIS REMOVES CAPPING AS A HINDRANCE
FOR CONVECTION, BUT A LACK OF SIGNIFICANT FORCING WILL KEEP
COVERAGE LOW.
A PATTERN CHANGE IS IN STORE LATE IN THE WEEK AS MID-LEVEL RIDGING
BREAKS DOWN AHEAD OF AN INCOMING SHORTWAVE. ENSEMBLE AND
DETERMINISTIC GUIDANCE AGREE IN THE EXISTENCE OF THIS FEATURE, BUT
DETAILS VARY WHICH DIRECTLY IMPACTS HOW LONG THE HEAT WILL LAST. THE
NBM INTERQUARTILE RANGE EXPRESSES CONFIDENCE IN THURSDAY BEING
ANOTHER HOT DAY, WITH A SPREAD OF 4 DEGREES AT KSTL AND 5 DEGREES AT
KIRK, SLIGHTLY CLOSER TO THE INFLUENCE OF THE SHORTWAVE. THIS IS
CONSISTENT WITH MOST MEMBERS IN THE WPC CLUSTER ANALYSIS FAVORING A
LESS AMPLIFIED SHORTWAVE AND SUGGESTS THAT A RETURN TO SEASONALLY
AVERAGE TEMPERATURES (77-80) MAY COME MORE GRADUALLY THAN MOST OF US
WOULD PREFER.
JAJA
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1032 PM CDT THU SEP 11 2025
VFR FLIGHT CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE PERIOD.
ISOLATED RIVER VALLEY FOG REMAINS POSSIBLE BEFORE SUNRISE, MAINLY
ACROSS THE EASTERN OZARKS. ANY FOG THAT DOES DEVELOP WILL
DISSIPATE QUICKLY AFTER SUNRISE. LIGHT AND VARIABLE TO SOUTHERLY
FLOW WILL PREVAIL.
CARNEY
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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