038
FXUS63 KLSX 170510
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1110 PM CST TUE DEC 16 2025
KEY MESSAGES
- SEASONABLY MILD TEMPERATURES WILL CONTINUE THROUGH WEDNESDAY NIGHT.
- RAIN SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED ON THURSDAY ALONG/AHEAD
OF A COLD FRONT. BEHIND THE FRONT, A BRIEF RETURN TO SEASONABLY
COLD TEMPERATURES IS EXPECTED.
SHORT TERM
(THROUGH LATE WEDNESDAY NIGHT)
ISSUED AT 233 PM CST TUE DEC 16 2025
A WEAK COLD FRONT IS FORECAST TO MOVE INTO NORTHEAST MISSOURI
AROUND MIDNIGHT TONIGHT, BUT LARGELY WASH OUT OVERNIGHT. SOUTHWEST
WINDS ARE FORECAST AHEAD OF THIS FEATURE TONIGHT. THESE WINDS
ALONG WITH VARIABLE CLOUDINESS POINT TO A MILDER NIGHT WITH LOWS
ONLY DROPPING BACK INTO THE UPPER 20S TO MID 30S.
MORE WIDESPREAD SUNSHINE IS FORECAST ON WEDNESDAY, WITH CHANCES OF
STRATUS FURTHER TO THE SOUTH COMPARED TO TODAY. THIS SHOULD MEAN A
BIT MORE WIDESPREAD LOW TO MID 50S ACROSS MUCH OF THE AREA. THE
EXCEPTION WILL BE FAR NORTHERN SECTIONS OF THE AREA, WHICH STILL HAS
SOME SNOW PACK. THE LATEST GOES-19 VISIBLE IMAGERY SHOWS THE SNOW
FIELD ERODING ON THE SOUTHWESTERN EDGE, BUT ENOUGH SHOULD REMAIN (AT
LEAST FOR ONE LAST DAY) ON WEDNESDAY TO IMPACT TEMPERATURES
SOMEWHAT. IN AREAS WITH REMAINING SNOW PACK, HIGHS IN THE MID 40S
ARE EXPECTED.
GOSSELIN
LONG TERM
(THURSDAY THROUGH NEXT TUESDAY)
ISSUED AT 233 PM CST TUE DEC 16 2025
(WEDNESDAY NIGHT - FRIDAY NIGHT)
WEDNESDAY NIGHT WILL INITIALLY START DRY, BUT THE CHANCES OF
SCATTERED SHOWERS LATE NIGHT AS LOW-LEVEL MOISTURE CONVERGENCE
INCREASES, PARTICULARLY IN SOUTHEAST MISSOURI AND SOUTHWEST
ILLINOIS. SIMILAR TO TUESDAY NIGHT, ANOTHER MILD NIGHT IS IN STORE
WITH INCREASING CLOUDINESS AND PERSISTENT SOUTHERLY SURFACE FLOW.
LOWS ARE FORECAST TO RANGE FROM THE UPPER 30S TO MID 40S ACROSS THE
REGION, OR 10-15 DEGREES ABOVE NORMAL FOR THE DATE.
THE MID/UPPER LEVEL TROUGH IS EXPECTED TO AMPLIFY ACROSS THE
MISSISSIPPI VALLEY EARLY THURSDAY. THIS IN TURN INCREASES THE
MID/UPPER LEVEL DIFFLUENCE DOWNSTREAM. STRONGER FORCING FOR LARGE-
SCALE ASCENT IS ALSO AIDED BY STRENGTHENING CONVERGENCE ALONG THE
SYNOPTIC COLD FRONT. THIS BOUNDARY IS FORECAST TO MOVE THROUGH
QUICKLY BETWEEN 1200 AND 1800 UTC THURSDAY. WIDESPREAD RAIN IS
FORECAST WITH THE FRONT. PROBABILITIES FOR AT LEAST 0.25" HAVE
STEADILY CLIMBED ON THE LREF OVER THE PAST 24-48 HOURS, NOW IN THE
20-60% RANGE FROM WEST TO EAST. A FEW ISOLATED THUNDERSTORMS ARE
ALSO EXPECTED. INSTABILITY CONTINUES TO LOOK VERY LIMITED, WITH
CHANCES OF EVEN 100+ J/KG OF MUCAPE ON THE EPS ONLY IN THE 10-30%
RANGE ON THURSDAY. THIS LIMITED INSTABILITY IS DRIVEN BY WEAK
MIDLEVEL LAPSE RATES AND MODEST LOW-LEVEL MOISTURE RETURN (TDS
NEAR 50) AHEAD OF THE FRONT.
BEHIND THE FRONT, WINDS WILL VEER MORE TO THE NORTHWEST WITH COLDER
AIR BEGINNING TO MOVE INTO THE AREA. HOWEVER, THE STRONGER PUSH OF
COLDER AIR LOOKS TO MOVE IN BEHIND A SECONDARY, WHICH LOOKS TO BE
ABOUT 4-5 HOURS BEHIND THE INITIAL FRONT. THIS SECONDARY COLD FRONT
WILL MOVE THROUGH DURING THE AFTERNOON/EARLY EVENING HOURS.
TEMPERATURES WILL INITIALLY COOL OFF INTO THE 40S DUE TO THE RAIN
AND THE INITIAL COLD FRONT, THEN STEADY OR EVEN SLOWLY CLIMB TOWARD
THE LOW 50S. FINALLY, LOOK FOR READINGS TO DROP QUICKLY BEHIND THE
SECONDARY FRONT INTO THE 30S, AND EVENTUALLY, 20S. BY FRIDAY
MORNING, LOWS IN THE UPPER 10S TO LOW 20S ARE FORECAST, OR NEAR 10
DEGREES BELOW NORMAL. THIS BRIEF BLAST OF SEASONABLY COLD AIR WILL
LAST ONLY ABOUT 24 HOURS TOTAL. HIGHS ON FRIDAY ARE EXPECTED TO BE
IN THE 30S FOR MUCH OF THE AREA BEFORE A WARMING TREND BEGINS FRIDAY
NIGHT.
(SATURDAY - NEXT TUESDAY)
QUASI-ZONAL FLOW ALOFT IS EXPECTED ACROSS THE CONUS THIS WEEKEND.
ENSEMBLE GUIDANCE SHOWS A STRONG MID/UPPER LEVEL TROUGH MOVING
ACROSS THE US-CANADIAN BORDER EARLY THIS WEEKEND, WITH A SURFACE LOW
NEARING THE NORTHERN GREAT LAKES SATURDAY EVENING. A COLD FRONT
ASSOCIATED WITH THIS SURFACE LOW IS LIKELY TO PASS THROUGH THE CWA
SATURDAY NIGHT, THOUGH THERE REMAINS SOME UNCERTAINTY AS TO HOW COLD
(OR NOT) IT WILL GET BEHIND THE BOUNDARY. THE INTER-QUARTILE RANGE
ON THE NBM REMAINS HIGH FOR TEMPERATURES SUNDAY INTO EARLY NEXT WEEK
IS STILL FAIRLY LARGE, ON THE ORDER OF ABOUT 10 DEGREES. THERE
DEFINITELY IS ROOM FOR A COLDER PUSH GIVEN THE STRONG BAROCLINICITY
FROM NORTH TO SOUTH. SIMILAR TO LATER THIS WEEK, IT LIKELY WOULDN'T
LAST LONG, BUT A SEASONABLY COLD PUSH OF AIR MAY BE ON THE CARDS
POTENTIALLY FOR EARLY NEXT WEEK.
GOSSELIN
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1105 PM CST TUE DEC 16 2025
VFR FLIGHT CONDITIONS ARE EXPECTED TO PREVAIL AT LEAST INTO
WEDNESDAY EVENING. SOME LOWER CEILINGS MAY BE BUILDING INTO PARTS
OF SOUTHEAST AND CENTRAL MISSOURI AT THE VERY END OF THE PERIOD,
HOWEVER GUIDANCE ISN'T VERY CLEAR ON HEIGHTS THAT FAR OUT JUST
YET. A WEAK COLD FRONT WILL DRIFT INTO THE AREA, BRIEFLY SHIFTING
THE WIND TO THE NORTHWEST ALONG AND NORTH OF I-70, BUT THE WIND
WILL QUICKLY TURN BACK TO THE SOUTHEAST BY WEDNESDAY AFTERNOON.
LOW LEVEL WIND SHEAR IS ALSO A POSSIBILITY WEDNESDAY EVENING,
THOUGH CONDITIONS LOOK MARGINAL SO HAVE NOT INCLUDED LLWS IN THE
TERMINAL FORECASTS AT THIS TIME
CARNEY
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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