295
FXUS63 KLSX 241944
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
244 PM CDT THU SEP 24 2026
KEY MESSAGES
- SEASONABLY COOL TEMPERATURES ALONG WITH CLOUDY CONDITIONS ARE
EXPECTED TO CONTINUE INTO THE WEEKEND.
- THERE ARE 30-60% CHANCES FOR LIGHT RAIN FRIDAY INTO SUNDAY,
GENERALLY ACROSS CENTRAL/NORTHEAST MO AND WEST-CENTRAL IL.
MORE WIDESPREAD AND SIGNIFICANT (0.50+ INCHES) RAIN IS
EXPECTED NEXT WEEK.
SHORT TERM /THROUGH FRIDAY/
ISSUED AT 242 PM CDT THU SEP 24 2026
A MID/UPPER-LEVEL RIDGE IS POSITIONED ACROSS NEW ENGLAND WITH A
CLOSED MID-LEVEL LOW TRAVERSING THE SOUTHERN PERIPHERY OF THIS RIDGE
TO THE EAST INTO THE OHIO RIVER VALLEY. THE SURFACE REFLECTION OF
THIS RIDGE, AN ANOMALOUSLY STRONG 1035MB HIGH, IS CENTERED ACROSS
SOUTHERN ONTARIO BRINING CONTINUED LOW-LEVEL NORTHEASTERLY FLOW INTO
THE REGION. THE CONTINUED LOW-LEVEL CAA FROM THE SLOW MOVING SURFACE
HIGH HAS ALLOWED FOR PERSISTENT AND RATHER IMPRESSIVE LOW-LEVEL
CLOUDS FOR LATE SEPTEMBER. ADDITIONALLY, A NARROW MID-LEVEL RIDGE IS
WORKING ITS WAY EASTWARD INTO THE MISSISSIPPI RIVER VALLEY. THE
EFFECTS OF THIS FEATURE (SUBSIDENCE/SINKING AIR) IS APPARENT ON
VISIBLE SATELLITE IMAGERY, INDICATED BY THE WESTERN EXTENT OF THE
STRATUS DECK THAT IS THROUGH THE CENTER OF MO. FOR MOST OF OUR AREA
TODAY, THIS STRATUS HAS GREATLY REDUCED DAYTIME HEATING, WITH
CURRENT AFTERNOON TEMPERATURES ONLY 4-7 DEGREES WARMER THAN THIS
MORNING'S LOWS. MOST LOCATIONS, AS OF 19Z, ARE IN THE MID TO LOW
60S, ASIDE FROM PORTIONS OF IL WHERE TEMPERATURES ARE NEAR 70, A
RESULT OF THINNER STATUS. A SLOW SCATTERING/LIFTING OF THE STRATUS
IS STILL FORECAST, BUT WILL LIKELY NOT HAPPEN UNTIL NEAR SUNSET OR
AFTER, RESULTING IN TEMPERATURES THAT STAY IN THE MID/UPPER 60S
ACROSS THE AREA. LOCATIONS THAT REMAINS MOSTLY CLOUDY TONIGHT WILL
STAY WARMER WITH LOWS IN THE 60S, WHILE LIGHT WINDS WILL ALLOW AREAS
THAT CLEAR TO LOWER INTO THE 50S, THANKS TO EFFICIENT RADIATIONAL
COOLING.
A SIMILAR SITUATION IS CERTAINLY POSSIBLE FRIDAY, AS BOTH THE
LOCATIONS OF THE MID-LEVEL RIDGE LOCATION AND LOW-LEVEL
NORTHEASTERLY CAA REMAIN RELATIVELY UNCHANGED FROM TODAY. STRATUS
MAY NOT BE AS WIDESPREAD FRIDAY FOR SOME AREAS, WITH HIGHER
CONFIDENCE IN CLOUDIER CONDITIONS NORTH OF I-70. THERE WILL BE
SUBTLE PIECES OF SHORTWAVE ENERGY TRAVERSING THE NORTHERN PERIPHERY
OF THE RIDGE, WORKING TO CREATE MORE WIDESPREAD CLOUD COVER ALONG
WITH SCATTERED SHOWERS. AS A RESULT, THERE IS A 30-60% CHANCE FOR
SHOWERS ACROSS NORTHEAST MO/WEST-CENTRAL IL FRIDAY INTO SATURDAY.
THIS WILL BE A LIGHT RAIN WITH LREF PROBABILITIES FOR 6HR RAINFALL
GREATER THAN 0.25" LESS THAN 30% ACROSS THE AREA. AREAS THAT STAY
LOCKED UNDER LOW-LEVEL CLOUDS WILL ONCE AGAIN STRUGGLE TO WARM OUT OF
THE 60S WHILE LOCATIONS THAT GET MORE CLEARING WILL WARM UP INTO THE
70S FRIDAY AFTERNOON.
LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/
ISSUED AT 242 PM CDT THU SEP 24 2026
MID-LEVEL PIECES OF ENERGY CONTINUE TO SWING AROUND THE
NORTHERN PERIPHERY OF A RIDGE CENTERED ACROSS TX, RESULTING IN
LOW CHANCES FOR SCATTERED RAIN SHOWERS CONTINUING INTO SATURDAY
AND POSSIBLY SUNDAY. AS WE PROGRESS FURTHER INTO THE WEEKEND,
SOME OF THE BETTER CHANCES (50%) MOVE SOUTH AND EAST REACHING
PORTIONS OF CENTRAL/EAST-CENTRAL MO. SIMILAR TO FRIDAY, MOSTLY
LIGHT RAIN SHOWERS ARE FORECAST AS THERE IS LESS THAN A 20%
CHANCE FOR THUNDERSTORMS. THE BETTER INSTABILITY (MUCAPE >1,000
J/KG) STAYS TO THE WEST ACROSS THE GREAT PLAINS THIS WEEKEND,
WITH LREF MEAN MUCAPE VALUES STAYING BELOW 200 J/KG ACROSS THE
ENTIRE AREA. BY TUESDAY, THE LARGE-SCALE PATTERN BEGINS TO SHIFT
AS A LONGWAVE TROUGH SWINGS INTO THE INTERMOUNTAIN WEST AND THE
SOUTHERN RIDGE INTO THE DEEP SOUTH. THIS PLACES OUR AREA IN
SOUTHERLY FLOW LEADING TO WARM/MOIST ADVECTION THAT WILL SUPPORT
INCREASING CHANCES FOR MORE WIDESPREAD SHOWERS ALONG WITH
THUNDERSTORMS. THE LREF ILLUSTRATES THIS POTENTIAL WELL AS
PROBABILITIES FOR PRECIPITATION >0.50" REACHES 50% FOR WESTERN
PORTIONS OF THE AREA, INDICATING THE INCREASING CHANCES FOR MORE
WIDESPREAD BENEFICIAL RAIN. WITH SOUTHERLY FLOW IN PLACE,
TEMPERATURES IQRS STEADILY INCREASE NEXT WEEK TO VALUES CENTERED
JUST ABOVE AVERAGE. HOWEVER, THESE IQR SPREADS INCREASE TO 10
DEGREES BY WEDNESDAY AND THURSDAY, SHOWING THE POTENTIAL FOR A
COLD FRONT BEHIND NEXT WEEKS SYSTEM. THIS REVEALS A RETURN TO
NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES ARE POSSIBLE BY THE
END OF NEXT WEEK.
AVIATION /18Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 1248 PM CDT THU SEP 24 2026
A WIDESPREAD FIELD OF MVFR STRATUS IS POSITIONED ACROSS THE AREA,
ENCOMPASSING ALL LOCAL TERMINALS. GUIDANCE HAS NOT HANDLED THE
COVERAGE AND DURATION OF THIS STRATUS DECK WELL, RESULTING IN A LOW
CONFIDENCE FORECAST REGARDING HOW CEILINGS EVOLVE OVER THE NEXT 3-6
HOURS. A GRADUAL LIFTING/SCATTERING OF THIS MVFR STRATUS FIELD WITH
CONDITIONS RETURNING TO VFR IS STILL EXPECTED, WITH UNCERTAINTY
REGARDING WHEN AND WHERE THAT HAPPENS. THE CURRENT TAFS INDICATE
THIS BY 23Z (LATE THIS AFTERNOON), BUT GIVEN RECENT TRENDS OF SLOWER
CLEARING, EVEN THIS MAY BE TOO EARLY. NEAR TERM TRENDS WILL NEED TO
BE MONITORED CLOSELY GIVEN THE UNCERTAIN FORECAST. A FEW
INTERMITTENT POCKETS OF MIST CANNOT BE RULED OUT, WITH LOW CHANCE
(20-30%) THESE LEAD TO BRIEF MVFR VISIBILITIES. LASTLY, THERE
REMAINS ANOTHER 30-50% CHANCE THAT MVFR CEILINGS RETURN TO PORTIONS
OF THE AREA TOMORROW MORNING, WHICH HAS BEEN INDICATED BY THE SCT025
GROUP. LIGHT NORTHEASTERLY SURFACE WINDS BECOME CALM AND VARIABLE
TONIGHT WITH EASTERLY WINDS RETURNING TOMORROW.
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
SHORT TERM...PEINE
LONG TERM...PEINE
AVIATION...PEINE
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page