960
FXUS63 KLSX 280440
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1040 PM CST MON JAN 27 2025
KEY MESSAGES
- DRY WEATHER WITH ABOVE-NORMAL TEMPERATURES IS FORECAST THROUGH
WEDNESDAY.
- WIDESPREAD RAINFALL IS FORECAST THURSDAY-FRIDAY. MOST LOCATIONS
ARE LIKELY (50-90+%) TO SEE AT LEAST A HALF INCH OF RAIN.
SHORT TERM
(THROUGH LATE TUESDAY NIGHT)
ISSUED AT 223 PM CST MON JAN 27 2025
A WEAK "COLD" FRONT WILL BE MOVING THROUGH THE REGION OVERNIGHT
TONIGHT. HOWEVER, THIS IS A PACIFIC FRONT WITH NO REAL CHANGE IN THE
AIR MASS. IN FACT, TEMPERATURES TONIGHT AND TUESDAY WILL ACTUALLY BE
WARMER THAN THE PAST 24 HOURS. CONTINUED WEST/SOUTHWEST WINDS WILL
PROVIDE LOW-LEVEL WARM AIR ADVECTION. THIS COMBINED WITH PLENTY OF
SUNSHINE AND SOME DOWNSLOPE OFF OF THE OZARK PLATEAU WILL COMBINE TO
YIELD HIGHS IN THE UPPER 40S TO MID 50S FROM NORTH TO SOUTH. GIVEN
THESE FAVORABLE CONDITIONS, LEANED CLOSE TO THE 90TH PERCENTILE OF
AVAILABLE MODEL GUIDANCE FOR HIGHS. LOWS TONIGHT ARE EXPECTED TO BE
IN THE MID 20S TO LOW 30S, WITH LOW TO MID 30S FORECAST TUESDAY
NIGHT.
GOSSELIN
LONG TERM
(WEDNESDAY THROUGH NEXT MONDAY)
ISSUED AT 223 PM CST MON JAN 27 2025
(WEDNESDAY - WEDNESDAY NIGHT)
THERE IS VERY LITTLE CHANGE IN THE SYNOPTIC PATTERN ACROSS THE CONUS
INTO WEDNESDAY AS A WEAK SURFACE RIDGE MOVES QUICKLY ACROSS THE MID-
MISSISSIPPI VALLEY. THERE IS WEAK LOW-LEVEL COLD AIR ADVECTION, BUT
850-HPA TEMPERATURES THEMSELVES REMAIN ABOVE NORMAL. ANOTHER SUNNY
DAY IS ALSO EXPECTED, SO WE ARE LOOKING AT ANOTHER DAY WITH HIGHS
MAINLY IN THE UPPER 40S TO MID 50S.
(THURSDAY - FRIDAY)
DETERMINISTIC MODELS AND ENSEMBLE GUIDANCE ARE IN GOOD AGREEMENT
WITH RESPECT TO THE NEXT WEATHER SYSTEM APPROACHING THE AREA EARLY
THURSDAY. THE CLOSED, CUTOFF LOW IS FINALLY EXPECTED TO MOVE
EASTWARD INTO THE SOUTH-CENTRAL PLAINS ON THURSDAY. STRONG MID/UPPER
LEVEL DIFFLUENCE AHEAD OF THIS FEATURE COMBINED WITH INCREASING LOW-
LEVEL MOISTURE ADVECTION IS EXPECTED TO YIELD WIDESPREAD RAIN ACROSS
THE AREA ON THURSDAY. THE RAIN SHOULD MOVE INTO PARTS OF SOUTHEAST
MISSOURI FIRST (LIKELY DURING THE MORNING HOURS), THEN SPREAD NORTH
AND EASTWARD ACROSS THE REMAINDER OF THE BI-STATE AREA DURING THE
DAYLIGHT HOURS. THE RAIN SHOULD BE HEAVIEST AND MOST CONSISTENT IN
PARTS OF SOUTHEAST MISSOURI AND SOUTHWEST ILLINOIS THROUGH THURSDAY
NIGHT, BUT A DRY SLOT SHOULD MOVE INTO THESE AREAS TOWARD EARLY
FRIDAY MORNING. THE FOCUS SHOULD SHIFT THEN FOR THE STEADIER RAIN TO
BE MORE CENTERED ACROSS NORTHEAST MISSOURI AND WEST-CENTRAL ILLINOIS
ON FRIDAY WITHIN THE DEFORMATION ZONE. THERE REMAINS HIGH CONFIDENCE
IN ALL OF THIS EVENT BEING RAIN, WITH TEMPERATURES EVEN ON FRIDAY IN
OUR NORTHERN COUNTIES WELL ABOVE FREEZING NOT ONLY AT THE SURFACE
BUT ALSO UP TO AT LEAST 925 HPA.
THIS WILL BE THE FIRST WIDESPREAD PRECIPITATION EVENT IN NEARLY 3
WEEKS. MOST LOCATIONS SHOULD SEE AT LEAST A HALF INCH OF RAIN, WITH
PROBABILITIES ON THE LATEST LREF ABOVE 50% EVERYWHERE. HIGHEST ODDS
(80-90+%) ARE IN PARTS OF SOUTHEAST MISSOURI AND SOUTHWEST ILLINOIS.
THIS IS ALSO WHERE 1+" TOTALS ARE MOST LIKELY (30-60%).
(FRIDAY NIGHT - NEXT MONDAY)
THE MID/UPPER LEVEL FLOW ACROSS THE CONUS IS MAINLY ZONAL, WITH A
FAST JET STREAM ACROSS THE PACIFIC OCEAN. THIS MEANS A RETURN TO
MILD AND DRY CONDITIONS FOR THIS UPCOMING WEEKEND HEADING INTO NEXT
WEEK.
GOSSELIN
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1033 PM CST MON JAN 27 2025
PRIMARY CONCERN DURING THE 06Z TAF PERIOD CONTINUES TO BE THE
POTENTIAL FOR LLWS, BOTH AT THE BEGINNING AND NEAR THE END OF THE
PERIOD. CURRENTLY MARGINAL LLWS HAS BEEN OBSERVED IN ACARS
SOUNDINGS AT STL THIS EVENING, PRIMARILY IN THE FORM OF WIND SPEED
SHEAR WITH A SMALL DIRECTIONAL COMPONENT AS WELL. SURFACE WINDS
ARE VARIABLE ACROSS TERMINALS, AND WIND SHEAR IS MAXIMIZED WHERE
SURFACE WINDS HAVE BECOME LIGHT (CPS/JEF IN PARTICULAR AS OF 04Z).
ADDITIONAL AMENDMENTS MAY BE NEEDED AT OTHER TERMINALS PENDING
SURFACE WIND TRENDS.
LLWS IS EXPECTED TO DIMINISH BEFORE SUNRISE, AND BREEZY SOUTHWEST
SURFACE WINDS WILL RESUME THROUGH THE DAY TOMORROW. A WEAK COLD
FRONT WILL CAUSE WINDS TO VEER SLIGHTLY IN THE EVENING, WITH MORE
PRONOUNCED VEERING JUST OFF THE SURFACE. MODEST LLWS MAY ALSO BE A
CONCERN TOMORROW EVENING AS A SLIGHTLY MORE PRONOUNCED
DIRECTIONAL COMPONENT IS PRESENT IN CURRENT MODEL GUIDANCE, WITH
SIMILARLY STRONG SPEED SHEAR.
BRC
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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