024
FXUS63 KLSX 261118
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
618 AM CDT SUN OCT 26 2025
KEY MESSAGES
- RAIN IS EXPECTED TODAY (90%+ CHANCE) FOR AREAS MAINLY ALONG AND SOUTH
OF I-70. HERE, THE PROBABILITY OF 0.5" OR MORE IS 60-80%.
- ANOTHER ROUND OF RAIN IS FORECAST TUESDAY INTO WEDNESDAY, WITH
THE PROBABILITY OF 0.5" OR MORE OF RAINFALL BEING 60-75%.
- SOME OF THE COOLEST AIR OF THE SEASON SO FAR IS EXPECTED MIDWEEK,
WITH A 70-80% CHANCE THAT HIGHS ON WEDNESDAY FAIL TO TOP 60
DEGREES.
SHORT TERM
(THROUGH MONDAY NIGHT)
ISSUED AT 232 AM CDT SUN OCT 26 2025
THE UPPER-LEVEL PATTERN IS ACTIVE ACROSS THE CONUS THIS MORNING PER
WATER VAPOR IMAGERY, WITH A TROUGH ALONG EACH COAST AND AN UPPER LOW
ENTERING THE MID SOUTH. AS THIS UPPER LOW HAS DRAWN CLOSER TO THE
CWA, MOISTURE AND LIFT HAS INCREASED TO THE POINT THAT THE
ASSOCIATED WAVES OF SHOWERS HAVE BEEN MORE PERSISTENT AND MORE
SUCCESSFUL IN REACHING THE SURFACE.
THIS TREND WILL ONLY INCREASE THROUGH THE DAYLIGHT HOURS AS THE LOW
PASSES DIRECTLY SOUTH OF THE CWA. A LOW-LEVEL JET IMMEDIATELY AHEAD
OF THE LOW WILL PROVIDE DEEP MOISTURE AND LIFT, WITH A RAIN SHIELD
EXPECTED TO ENCOMPASS MUCH OF THE AREA SOUTH OF THE I-70 CORRIDOR
STARTING DURING THE LATE MORNING AND CONTINUING THROUGH THE EARLY
EVENING. BY THE TIME THE MORE PERSISTENT RAIN WINDS DOWN, AREAS
SOUTH OF I-70 WILL SEE 0.2-0.5" OF ACCUMULATION, WITH LOCALIZED
AREAS OF UP TO 1" ACROSS FAR SOUTHEASTERN MISSOURI. MOISTURE
WRAPPING AROUND THE NORTHERN PERIPHERY OF THE LOW WILL KEEP A LOW
CHANCE FOR LIGHT SHOWERS AND SPRINKLES OVER SOUTHEASTERN MISSOURI
AND SOUTHERN ILLINOIS THROUGH MONDAY MORNING.
DUE TO CLOUD COVER AND COOLER MID-LEVEL TEMPERATURES FROM THE
DEPARTING LOW AND THE APPROACHING WESTERN TROUGH, AFTERNOON HIGHS
WILL BE SIMILAR TO WHAT IS EXPECTED TODAY AS HIGHS TOP OUT IN THE
UPPER 50S TO AROUND 60 DEGREES - ROUGHLY AT TO 10 DEGREES BELOW
CLIMATOLOGICAL NORMALS. THIS WILL SERVE AS A BRIEF BREAK IN THE
ACTIVE WEATHER AHEAD OF THE AFOREMENTIONED WESTERN TROUGH IMPACTING
THE AREA STARTING TUESDAY.
ELMORE
LONG TERM
(TUESDAY THROUGH SATURDAY)
ISSUED AT 232 AM CDT SUN OCT 26 2025
AT THE START OF THE EXTENDED FORECAST RANGE ON TUESDAY, GUIDANCE
CONSENSUS IS THAT A HIGHLY AMPLIFIED UPPER-LEVEL TROUGH WILL BE
DIGGING EQUATORWARD ACROSS THE GREAT PLAINS. THIS TROUGH WILL SWEEP
A POTENT COLD FRONT THROUGH THE PLAINS INTO THE MIDWEST TUESDAY INTO
WEDNESDAY. ALONG THIS FRONT, GUIDANCE HAS COME INTO BETTER CONSENSUS
IN CYCLOGENESIS ALONG THIS FRONT AS A SHORTWAVE ROUNDS THE BASE OF
THE TROUGH LATE TUESDAY INTO WEDNESDAY. A MAJORITY OF SOLUTIONS
FAVOR CYCLOGENESIS OVER THE CENTRAL PLAINS OR MIDDLE MISSISSIPPI
VALLEY - FAVORING SEVERAL ROUNDS OF SOAKING RAINFALL FOR THE CWA.
THE EXACT TRACK OF THE LOW IS UNCERTAIN DUE TO DIVERGING SOLUTIONS
IN THE PHASING OF THE TROUGH AS IT BECOMES CUT OFF AND INTERACTS
WITH ANOTHER UPPER LOW WEDNESDAY INTO THURSDAY. A SLOWER MOVING
SURFACE LOW THAT TRACKS CLOSER TO THE CWA WOULD LEAD TO GREATER
RAINFALL TOTALS, WHILE A FASTER LOW AND/OR ONE THAT TRACKS FURTHER
AWAY FROM THE CWA WILL LEAD TO LOWER TOTALS. LOOKING AT THE MOST
RECENT NBM INITIALIZATION, THE PROBABILITY FOR 0.5" OR GREATER ONCE
RAIN CHANCES DIE DOWN WEDNESDAY NIGHT IS 60-75% ACROSS THE CWA, WITH
THE HIGHER VALUES ACROSS SOUTHERN ILLINOIS.
THE CWA WILL BE FULLY BEHIND THE FRONT ON WEDNESDAY, WITH SOME OF
THE COOLEST AIR OF THE SEASON THUS FAR SPREADING INTO THE AREA IN
ITS WAKE. THE INTER QUARTILE RANGE OF THE RECENT GLOBAL ENSEMBLE
INITIALIZATIONS IS CONFINED TO THE LOW TO MID 50S FOR HIGHS DURING
THE AFTERNOON, WITH LOWS POTENTIALLY DROPPING INTO THE MID 30S FOR
MANY LOCATIONS THAT NIGHT. THIS RAISES CONCERNS FOR FROST POTENTIAL;
HOWEVER, WITH THE SURFACE LOW RELATIVELY CLOSE BY, CLOUD COVER AND
WINDS MAY MITIGATE THIS THREAT. TEMPERATURES GRADUALLY MODERATE TO
END THE WEEK, BUT HOW MUCH SO DEPENDS ON HOW QUICKLY THE CUTOFF
PUSHES EASTWARD. A SLOWER LOW WILL LEAD TO A SLOWER REBOUND IN
TEMPERATURES, WHILE QUICKER LOW WILL ALLOW FOR TEMPERATURES TO RISE
TO SEASONAL VALUES BY SATURDAY.
ELMORE
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 608 AM CDT SUN OCT 26 2025
A SLOW MOVING WEATHER SYSTEM WILL CONTINUE TO IMPACT THE LOCAL
TERMINALS THROUGH THE FORECAST PERIOD, THOUGH KUIN IS EXPECTED TO
STAY JUST TO THE NORTH OF IMPACTS. THROUGH THE MORNING, AN
EXPANSIVE AREA OF LIGHT RAIN WILL SPREAD NORTHWARD AND OVERCOME
KCOU, KJEF, KSUS, KSTL, AND KCPS. CONFIDENCE IS CURRENTLY HIGH
THAT THE HEAVIER RAIN CAPABLE OF MVFR VISIBILITIES WILL REMAIN
SOUTH OF THESE TERMINALS, BUT THERE IS A LOW CHANCE FOR BRIEF
BOUTS OF 4-5 MILE VISIBILITIES. WITH THE MORE PERSISTENT RAINFALL
WILL COME AN INCREASE IN LOW-LEVEL MOISTURE, LEADING TO CEILINGS
GRADUALLY DROPPING. KCOU AND KJEF WILL BE ON THE EDGE OF THE
CEILINGS FOR MUCH OF THE DAY, AND CEILINGS AT THESE TWO TERMINALS
MAY DECREASE SOONER THAN FORECAST. RAIN WILL BECOME MORE SCATTERED
LATER THIS EVENING BEFORE ENDING, THOUGH CEILINGS WILL CONTINUE
TO DROP THROUGH THE END OF THE PERIOD, WITH A LOW CHANCE OF IFR
CEILINGS POSSIBLE VERY LATE IN THE PERIOD.
ELMORE
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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