565
FXUS63 KLSX 021208
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
708 AM CDT THU OCT 2 2025
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH EARLY NEXT WEEK.
- THERE IS A SLIGHT CHANCE (15%) OF SHOWERS AND/OR A STRAY
THUNDERSTORM THIS AFTERNOON OVER THE EASTERN OZARKS INTO
SOUTHWEST ILLINOIS. BETTER CHANCES (30-35%) ARRIVE TUESDAY INTO
WEDNESDAY.
SHORT TERM
(THROUGH LATE FRIDAY AFTERNOON)
ISSUED AT 234 AM CDT THU OCT 2 2025
EARLY THIS MORNING, RIDGING WAS VIRTUALLY STACKED OVER THE OHIO
VALLEY INTO THE NEW ENGLAND REGION AS A WEAK UPPER LEVEL TROUGH
EXTENDED SOUTHWARD OVER THE MISSISSIPPI VALLEY. IR SATELLITE SHOWED
HIGH CLOUDS EXTENDING FROM THE GREAT LAKES REGION SOUTHWESTWARD OVER
THE EASTERN OZARK IN RELATION TO THE UPPER TROUGH. THE PAST FEW
MORNINGS, FOG HAS DEVELOPED WITHIN THE LOWER ELEVATIONS AND AREAS
ADJACENT TO RIVER VALLEYS, BECOMING LESS PREVALENT OVER THE LAST
COUPLE OF MORNINGS. THOUGH IT CAN'T BE ENTIRELY RULED OUT IN THE
TYPICAL AREAS AROUND SPIRIT, PARKS AND JEFFERSON CITY AIRPORTS, IT
LIKELY TO BE MITIGATED BY THE INCREASE IN HIGH CLOUDS WITH LITTLE
DISRUPTION/IMPACT.
AS WE PROGRESS THROUGH TODAY, HIGH CLOUDS WILL GRADUALLY THIN AS
THICKER CLOUD COVER MOVES EAST. TEMPERATURES BUMP UP 1-2 DEGREES
OVER YESTERDAY, SUPPORTING TEMPERATURES IN THE MID TO UPPER 80S ONCE
AGAIN. MEANWHILE, SOUTHERLY MID-LEVEL FLOW ROUNDING THE WESTERN SIDE
OF THE MID-LEVEL RIDGE WILL CRAWL NORTHWARD THROUGH THE AFTERNOON.
AS MOISTURE INCREASES THROUGH DIURNAL PEAK, SCATTERED MID-LEVEL
CLOUDS ARE EXPECTED TO DEVELOP OVER SOUTHERN SECTIONS OF MISSOURI
AND ILLINOIS, ACCOMPANIED BY ISOLATED SHOWERS. SB CAPE STILL LOOKS
ON TRACK TO CLIMB TO 1000-1500 J/KG WITH SB LR BETWEEN 8-9C.
HOWEVER, MID-LEVEL LR ARE ONLY AROUND 6C WITH WEAK FLOW THROUGHOUT
THE VERTICAL EXTENT OF MODEL SOUNDINGS SAMPLED. A STRAY THUNDERSTORM
IS POSSIBLE, BUT CONSIDERING THE WEAK FLOW ENVIRONMENT, WEAK MID-
LEVEL LAPSE RATES AND SLOW-MOVING NATURE OF THE ACTIVITY WILL BE
DIFFICULT TO SUSTAIN ANYTHING VERY LONG., MUCH LESS BECOME
ORGANIZED. HREF 24-HOUR PROBABILITIES FOR MEASURABLE PRECIPITATION
SHOW A BROAD SMATTERING OF 10-30% ALONG WITH ISOLATED POCKETS OF 40-
50% RUNNING ALONG AND SOUTH OF I-44 (MO) AND SOUTH OF I-64 (IL).
WITH SURFACE DEWPOINT DEPRESSIONS AROUND 20 DEGREES, THE LIGHTER
SHOWERS MAY LARGELY EVAPORATE, AS THE MORE GLORIFIED SHOWERS PRODUCE
A FEW HUNDREDTHS OF AN INCH TO PERHAPS A LOCALIZED TENTH OF AN INCH.
SOME OF THE HI-RES GUIDANCE PLOT A COUPLE OF SHOWERS FRIDAY
AFTERNOON, BUT I'M NOT AS CONFIDENT THIS WILL OCCUR AS UPPER LEVEL
RIDGING AMPLIFIED OUT OF THE SOUTHWEST AND THE MID-LEVEL RIDGE
RETROGRADES WESTWARD INTO THE MID-MISSISPPI VALLEY. MODEL SOUNDING
ALSO INDICATE MID-LEVELS DRYING SOME ON MORE OF A WESTERLY FLOW
COMPONENT. THIS FAVORS A DRY FORECAST WITH A RETURN TO MOSTLY SUNNY
SKIES. HIGHS FRIDAY AND SATURDAY REMAIN IN THE MID TO UPPER 80S WITH
MORNING LOWS LARGELY IN THE LOW TO MID-60S.
MAPLES
LONG TERM
(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 234 AM CDT THU OCT 2 2025
THE RIDGING PATTERN PROTECTS THE ONGOING STREAK OF ABOVE NORMAL
TEMPERATURES AND DRY CONDITIONS THROUGH SUNDAY. BY MONDAY, CERTAINTY
BEGINS TO DIP BEFORE ENSEMBLE SPREAD INCREASES DRAMATICALLY TUESDAY
AND BEYOND.
THE SYNOPTIC PATTERN FINALLY BEGINS TO SHOW A SHIFT EARLY IN THE
WEEK WITH RAIN CHANCES GRADUALLY BEING INTRODUCED FROM MONDAY INTO
TUESDAY. AS THE AXIS TO THE UPPER RIDGE MOVES OVER THE EASTERN
SEABOARD, FRAGMENTS OF VORACITY'S SPOKE NORTHWARD OUT OF THE GULF
AROUND THE WESTERN SIDE OF THE MID-LEVEL RIDGE. MEANWHILE, A COLD
FRONT BEGINS TO DROP IN FROM THE NORTH AND THIS IS WHERE GUIDANCE
BEGINS TO DIVERGE. ACCORDING TO GLOBAL DETERMINIST GUIDANCE, THE
FRONT IS QUICK ENOUGH TO BISECT MISSOURI (GFS) BY MONDAY AFTERNOON
OR LAGGING NEAR THE MISSOURI/IOWA BORDER (ECM). GRAPHICAL OUTPUT
FROM THE HREF TEMPERATURES SPREADS SHOW TWO AREAS OF UNCERTAINTY 1)
ONE AREA STRETCHING FROM CHICAGO THROUGH QUINCY AND KANSAS CITY,
WHICH IS ASSOCIATED WITH THE COLD FRONT 2) A SECOND OVER SOUTHEAST
MISSOURI AND SOUTHWEST ILLINOIS THAT IS LIKE THE RESULT OF RAIN
POTENTIAL. THE DISPARITY LEAVES TOO MUCH IN QUESTION WITH RESPECT TO
COVERAGE AND LOCATION-SPECIFIC CHANCES. LOW RAIN CHANCES (20-25%)
OVER PARTS OF THE AREA SEEMS SUFFICIENT WITH THE LACK OF CONFIDENCE.
NONETHELESS, MONDAY MAY BRING LIGHT RAIN TO SOME WITH SOUTHEAST
MISSOURI AND SOUTHWEST ILLINOIS MORE FAVORABLE FOR SCATTERED
ACTIVITY MONDAY AFTERNOON.
RAIN POTENTIAL IS BEGINNING TO LOOK A LITTLE BETTER TUESDAY INTO
WEDNESDAY. DESPITE THE DISPARITY MENTIONED ABOVE, THE FRONT
EVENTUALLY GET INTO THE AREA BY TUESDAY WITH LREF ENSEMBLE MEMBERS
FAVORING TUESDAY NIGHT INTO WEDNESDAY FOR MEASURABLE RAINFALL.
LATEST LREF SHOW THE HIGHEST 6-HOUR PROBABILITIES (30-40%) ORIENTED
IN AN EAST-WEST LINE ALONG THE FRONT, PROGRESSING NORTH TO SOUTH
BETWEEN 00Z WEDNESDAY (TUESDAY NIGHT) AND WEDNESDAY MORNING.
TEMPERATURES TREND COOLER OVER THE LATER HALF OF THE WEEK, BUT HOW
MUCH OF THE COOL AIR INFILTRATES THE LOCAL AREA IS NOT ENTIRELY
CERTAIN EITHER. THE ECM HAS BEEN TAKING A BROAD SURFACE RIDGE INTO
THE EASTERN GREAT LAKES AND NEW ENGLAND REGION (WARMER), WHILE THE
GFS HAS IT BUILDING FURTHER SOUTH (COOLER). THE 00Z ENSEMBLE RUN
LOOKS A BIT MORE ENCOURAGING AS BOTH ENSEMBLE MEANS SHOW A RELATIVE
TREND TOWARD NORMAL TEMPERATURES WITH HIGHS IN THE 70S AND LOWS IN
THE 50S. SHOULD THIS TREND CONTINUE TO SHOW TIGHTENING IN THE
ENSEMBLE DATA, WE MIGHT FINALLY SEE A RETURN TO MORE FALL-LIKE
WEATHER.
MAPLES
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 705 AM CDT THU OCT 2 2025
ISOLATED SHOWERS ARE POSSIBLE TODAY, BUT SHOULD LARGELY REMAIN
OVER SOUTHEAST MISSOURI AND SOUTHWEST ILLINOIS. MID/HIGH VFR
CLOUDS WILL OCCASIONALLY STREAM THROUGH THE REGION WITH LIGHT AND
VARIABLE SURFACE WINDS THROUGH THE END OF THE PERIOD.
MAPLES
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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