797
FXUS63 KLSX 250901
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
301 AM CST THU DEC 25 2025
KEY MESSAGES
- A QUASI-STATIONARY BOUNDARY MEANDERS THROUGH THE REGION THROUGH
SATURDAY WITH WELL ABOVE NORMAL TEMPERATURES FAVORED. WHERE
PARTIAL CLEARING OCCURS, TEMPERATURES WILL BE NEAR-RECORD
TERRITORY.
- SHOWERS AND THUNDERSTORMS ARE BECOMING MORE LIKELY SUNDAY ALONG
A STRONG COLD FRONT. MUCH COLDER TEMPERATURES RETURN NEXT WEEK.
SHORT TERM
(THROUGH LATE FRIDAY AFTERNOON)
ISSUED AT 256 AM CST THU DEC 25 2025
BROAD MIDLEVEL RIDGING REMAINS IN PLACE ACROSS THE MID-MISSISSIPPI
VALLEY THROUGH THE PERIOD, RESULTING IN WEAK HEIGHT TENDENCIES AND
LITTLE SYNOPTIC-SCALE FORCING. WATER VAPOR IMAGERY CONTINUES TO
DEPICT SUBSIDENT FLOW ALOFT, SUPPORTING THE MAINTENANCE OF A STRONG
LOW-LEVEL INVERSION. BENEATH THE INVERSION, A QUASI-STATIONARY
FRONTAL BOUNDARY REMAINS POSITIONED NEAR THE I-70 CORRIDOR, WITH
SHALLOW COOL AIR NORTH OF THE BOUNDARY AND WARMER, MORE HUMID AIR TO
THE SOUTH.
SURFACE OBSERVATIONS AS OF 08Z THIS MORNING SHOW WIDESPREAD FOG
NORTH AND WEST OF THE ST. LOUIS METRO, WITH VISIBILITY REDUCTIONS
AROUND 1/4 MILE AND LOW IN SOME CASES. FOG IS SLOWLY EXPANDING
SOUTHWARD ALONG THE BOUNDARY, BUT HAS MADE SLOWER PROGRESS IN THE
LAST HOUR. THAT BUILDS CONFIDENCE THAT THE DENSE FOG ADVISORY IS IN
GOOD STANDING. CONTINUED LOW-LEVEL MOISTURE ADVECTION ATOP THE
SHALLOW COOL LAYER, COMBINED WITH WEAK MIXING, WILL SUPPORT LOW
STRATUS AND FOG THROUGH AT LEAST MID-MORNING, ESPECIALLY ALONG AND
NORTH OF I-70. THE PRIMARY CHALLENGE OTHERWISE, WILL BE THE IMPACT
OF PERSISTENT FOG AND LOW CLOUDS ON TEMPERATURE TRENDS. RECENT
TRENDS FAVOR SLOWER EROSION THAN GUIDANCE SUGGESTS, CURBING
POTENTIAL HIGHS AT AFFECTED LOCATIONS.
DESPITE ANOMALOUSLY WARM TEMPERATURES (15-18C AT 850MB) ALOFT, HIGH
TEMPERATURES TODAY WILL BE HIGHLY CONDITIONAL ON CLOUD EVOLUTION.
WHERE FOG AND STRATUS PERSIST INTO THE LATE MORNING OR EVEN EARLY
AFTERNOON, PARTICULARLY ACROSS NORTHERN MISSOURI AND WEST-CENTRAL
ILLINOIS, HIGHS WILL REMAIN CONFINED TO THE 50S. MANUAL ADJUSTMENTS
WERE MADE TO LOWER TEMPERATURES A FEW DEGREES NORTH OF THE FRONT,
WHERE FOG AND STRATUS IS FAVORED TO PERSIST LATER INTO THE MORNING.
FARTHER SOUTH/SOUTHWEST, INCLUDING AREAS SOUTH OF THE MISSOURI RIVER
AND THE ST. LOUIS METRO, PARTIAL CLEARING, IMPROVED MIXING AND
DOWNSLOPE SOUTHWEST FLOW OFF THE OZARKS WILL ALLOW TEMPERATURES TO
RISE WELL INTO THE 60S. FASTER-THAN-EXPECTED CLEARING WOULD RESULT
IN WARMER OUTCOMES WITH 70S FAVORED IN SIMILAR AREAS AS WEDNESDAY.
TO THE CONTRARY, SLOWER CLEARING WOULD RESULT IN HIGH TEMPERATURES
COOLER-THAN-FORECAST. HREF SHOW MEAN CLOUD COVER OF 90% FROM KCOU TO
KSTL THROUGH SOUTHWEST ILLINOIS. THIS COINCIDES WITH AN AREA WHERE
30-50% OF THE HREF ENSEMBLES PUSH HIGH TEMPERATURES ABOVE 70
DEGREES. WHILE THIS MAY CURB CONFIDENCE IN WARMTH OF THIS MAGNITUDE,
YESTERDAY'S TEMPERATURE BEHAVIOR SERVES AS THE BEST REFERENCE FOR
TODAY'S EXPECTATIONS.
BY FRIDAY MORNING, THE FRONT BEGINS TO SHIFT BACK TO THE NORTH.
ANOTHER ROUND OF FOG IS EXPECTED OVER NORTHERN SECTIONS OF THE
FORECAST AREA, WITH LOCALLY DENSE FOG POSSIBLE. THE NORTHWARD
ADJUSTMENT IN THE BOUNDARY DRAWS WARMTH AND MOISTURE NORTHWARD,
RESULTING IN PARTIAL CLEARING OVER MUCH OF THE AREA. THIS WILL WARM
HIGH TEMPERATURES SLIGHTLY OVER AREAS THAT HAVE ALREADY BEEN IN THE
WARM SECTOR, WHILE TEMPERATURES NORTH OF I-70 CLIMB ROUGHLY 4-7
DEGREES HIGHER THAN THURSDAY.
MAPLES
LONG TERM
(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 256 AM CST THU DEC 25 2025
FRIDAY NIGHT MARKS THE TRANSITION TO A MORE PROGRESSIVE PATTERN THAT
CONTINUES INTO SATURDAY AS A DEEPENING WESTERN CONUS TROUGH ADVANCES
EASTWARD. HEIGHT FALLS AND STRENGTHENING SOUTHWESTERLY FLOW ALOFT
WILL ALLOW THE BOUNDARY TO LIFT EVEN FURTHER NORTHWARD, SUPPORTING
RENEWED MOISTURE ADVECTION AND CONTINUATION OF ABOVE-NORMAL
TEMPERATURES.
A STRONG COLD FRONT MOVES THROUGH THE REGION VERY LATE SATURDAY
NIGHT INTO SUNDAY WITH LATEST TRENDS SHOWING A MUCH LATER ARRIVAL
THAT JUST 24 HOURS AGO. THIS KEEP WARMER AIR OVER AT LEAST THE
SOUTHEAST HALF OF THE CWA THROUGH SUNDAY. ADDITIONALLY, IT BOOSTS
CONVECTIVE POTENTIAL OVER THE REGION SUNDAY AFTERNOON. INCREASING
LARGE-SCALE ASCENT ASSOCIATED WITH POSITIVE VORTICITY ADVECTION AND
FRONT CONVERGENCE WILL SUPPORT WIDESPREAD SHOWERS AND THUNDERSTORMS
ALONG AND AHEAD OF THE FRONT. THE MAGNITUDE OF INSTABILITY IS
UNCERTAIN AT THIS RANGE WITH THE LATEST LREF DATA SHOWING MEAN
SBCAPE OF 200-300 J/KG FROM SPRINGFIELD, MO THROUGH ST. LOUIS
THROUGH NORTHERN INDIANA. CAPE VALUES MIGHT SOUND LOW, BUT WINTER
SYSTEMS TEND TO PERFORM BETTER WITH MUCH COLDER AIR ALOFT.
ADDITIONALLY, MEAN SHEAR VALUES APPROACH 60 KNOTS WITH A SLOWING
TREND IN BOUNDARY ARRIVAL. THIS MAINTAINS THE MOISTURE ADVECTION
SUNDAY AND OPENS THE WINDOW FOR BETTER THUNDERSTORM POTENTIAL, SOME
OF WHICH COULD PRODUCE STRONG WIND GUSTS SUNDAY AFTERNOON.
CONSIDERING THE UNCERTAINTY IN TIMING, THIS WILL BE SOMETHING TO
CONTINUE TO MONITOR AS WE HEAD INTO THE WEEKEND.
TIMING DIFFERENCES BETWEEN GUIDANCE IS ALSO IMPACTING PRECIPITATION
TYPES AMONG SOME OF THE ENSEMBLE DATA, SHOWING A VERY BRIEF AND LOW
CHANCE (<10%) OF FLURRIES. WHILE NOT ENTIRELY IMPOSSIBLE, THE SPREAD
MAY BE HANGING ON TO PRECIPITATION A LITTLE LONGER THAN IT SHOULD
BE, RESULTING IN A BRIEF CHANGEOVER. NBM, HOWEVER, EVACUATES POPS
WELL BEFORE SUB-FREEZING AIR MAKES IT INTO THE CWA. THEREFORE, IF A
BRIEF CHANGEOVER WERE TO OCCUR, IT ISN'T EXPECTED TO RESULT IN
IMPACTS. THE TEMPERATURES DROP BEHIND THE FRONT IS ALMOST
REMINISCENT OF THE DAKOTAS, WITH A FEW LOCATIONS NEARLY 50
DEGREES COLDER BY MONDAY MORNING.
FORECAST CONFIDENCE DECREASES AS WE HEAD INTO NEXT WEEK. ENSEMBLE
GUIDANCE INDICATES A WIDE SPREAD IN TEMPERATURE OUTCOMES MONDAY
THROUGH WEDNESDAY, WITH INTERQUARTILE RANGES OF ROUGHLY 15-20
DEGREES. THIS SPREAD IS MOST PRONOUNCED IN DIURNAL MAXIMUMS DUE TO
CLOUD COVER AND RELATIVE POSITION/AMPLITUDE OF EASTERN CONUS
TROUGHING AND WESTERN CONUS RIDGING. SOLUTIONS RANGE FROM NORTHWEST
FLOW AND BELOW NORMAL TEMPERATURES TO A QUICKER RETURN TO RIDGING
AND MODERATING TEMPERATURES. PRECIPITATION CHANCES APPEAR MINIMAL
BEYOND SUNDAY.
MAPLES
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1009 PM CST WED DEC 24 2025
DENSE FOG AND IFR STRATUS ARE PLAGUING MUCH OF THE CWA NORTH OF
I-70. THE CLOUD DECK WILL CONTINUE TO CRAWL SOUTH THIS MORNING,
WITH ALL TERMINALS RECEIVING A TASTE OF IT BY SUNRISE. FOG WILL
CONTINUE TO THICKEN THIS MORNING AS WELL, SWALLOWING ALL
TERMINALS. THE MOST DENSE FOG, FOR LOCATIONS THAT ARE NOT ALREADY
EXPERIENCING IT, IS EXPECTED TO OCCUR BETWEEN SUNRISE AND NOON
CHRISTMAS MORNING. ALONG AND JUST SOUTH OF I-70, RIVER VALLEY
SITES ARE EXPECTED TO SEE THE MOST DENSE FOG, WITH TOPOGRAPHY
MATTERING LESS AND LESS WITH NORTHERN EXTENT. FOG WILL CLEAR BY
MIDDAY, AND CEILINGS ARE FORECAST TO LIFT TO MVFR AT ABOUT THE
SAME TIME. CLEARING WILL OCCUR FROM SOUTH TO NORTH WITH VFR
CONDITIONS FORECAST BY LATE AFTERNOON/EARLY EVENING FOR LOCATIONS
SOUTH OF I-70 AND WEST OF I-55. ELSEWHERE, LOW STRATUS MAY LINGER
THROUGH CHRISTMAS NIGHT.
JAJA
CLIMATE
ISSUED AT 220 PM CST MON DEC 22 2025
WELL ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR MUCH OF CHRISTMAS
WEEK. RECORD HIGH TEMPERATURES ARE WITHIN REACH ON SEVERAL DAYS.
DAILY RECORD HIGHS FOR EACH SITE ARE LISTED BELOW.
ST LOUIS COLUMBIA QUINCY
12/2473(2021)74(2021)69(2021)
12/2571(1889)74(1889)66(2019)
12/26 70(1942) 69(1942) 63(1942)
12/27 72(1971) 71(1946) 70(1946)
THE ALL TIME DECEMBER RECORD HIGHS ARE LISTED BELOW.
ST LOUIS - 76 MOST RECENTLY ON DEC 3, 2021
COLUMBIA - 76 MOST RECENTLY ON DEC 15, 2021
QUINCY - 75 ON DEC 15, 2021
LSX WATCHES/WARNINGS/ADVISORIES
MO...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR AUDRAIN MO-
BOONE MO-CALLAWAY MO-KNOX MO-LEWIS MO-LINCOLN MO-MARION MO-
MONROE MO-MONTGOMERY MO-PIKE MO-RALLS MO-SAINT CHARLES MO-
SHELBY MO-WARREN MO.
IL...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR ADAMS IL-
BOND IL-BROWN IL-CALHOUN IL-FAYETTE IL-GREENE IL-JERSEY IL-
MACOUPIN IL-MADISON IL-MONTGOMERY IL-PIKE IL.
WFO LSX
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