280
FXUS63 KLSX 180921
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
321 AM CST WED DEC 18 2024
KEY MESSAGES
- MAINLY DRY WEATHER IS EXPECTED THROUGH THE WEEKEND.
- TEMPERATURES WILL TREND COOLER THROUGH THE END OF THE WEEK BEFORE
WARMING GRADUALLY NEXT WEEK.
SHORT TERM
(THROUGH LATE THURSDAY AFTERNOON)
ISSUED AT 317 AM CST WED DEC 18 2024
THE BULK OF THE SHOWERS HAVE ALREADY MOVED OUT OF THE CWA EARLY THIS
MORNING. THIS IS DUE TO THE LOW LEVEL MOISTURE CONVERGENCE
ASSOCIATED WITH THE LOW LEVEL JET AND THE STRONGEST ASCENT WITH THE
MID LEVEL LEVEL TROUGH MOVING EAST OF THE AREA. THERE WILL STILL BE
SOME LIGHT SCATTERED SHOWERS AND SPRINKLES LINGERING OVER THE AREA
UNTIL AROUND SUNRISE BEFORE DRIER AIR MOVES INTO THE REGION. THEN
MAINLY DRY WEATHER IS EXPECTED THE REST OF THE DAY INTO THURSDAY AS
A SHORTWAVE RIDGE WILL MOVE ACROSS THE AREA ALONG WITH AN ASSOCIATED
SURFACE HIGH TONIGHT.
HIGH TEMPERATURES TODAY WILL BE NOTABLY COOLER THAN YESTERDAY WITH
THE COLD AIR ADVECTION BEHIND A COLD FRONT ALONG WITH SOME LOW
CLOUDS. THERE WILL BE SOME CLEARING TONIGHT AND THE WINDS WILL TURN
LIGHT WITH THE RIDGE MOVING THROUGH ALLOWING LOWS TO DROP BACK INTO
THE 20S. HIGHS ON THURSDAY WILL BE SIMILAR TODAY AS WINDS TURN
SOUTHWEST AHEAD OF THE NEXT COLD FRONT.
BRITT
LONG TERM
(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 317 AM CST WED DEC 18 2024
THERE IS STILL GOOD AGREEMENT IN THE DETERMINISTIC AND ENSEMBLE
GUIDANCE THAT TWO TROUGHS WILL MOVE ACROSS THE MIDWEST ON THURSDAY
NIGHT AND SATURDAY. QPF WITH THESE SYSTEMS ARE STAYING TO THE
NORTH AND EAST OF THE CWA AND THERE CONTINUES TO BE LESS THAN 10
PERCENT LREF MEMBERS PRODUCING ANY PRECIPITATION. TEMPERATURES
BEHIND THE COLD FRONT THAT WILL MOVE THROUGH MISSOURI AND ILLINOIS
ON THURSDAY NIGHT ASSOCIATED WITH THE CLIPPER WILL BE COOLER WITH
HIGHS ON FRIDAY AND SATURDAY ONLY IN THE 30S.
A MORE ACTIVE PATTERN WILL BE SETTING UP EARLY NEXT WEEK AS THE LREF
IS ADVERTISING AN INCREASING CHANCE OF PRECIPITATION AHEAD OF AN
UPPER TROUGH MOVING INTO THE MIDWEST FROM THE PLAINS. CURRENTLY THE
BEST CHANCES (30-50%) WILL WAIT UNTIL MONDAY NIGHT AND TUESDAY WHEN
THE UPPER TROUGH WILL ENCOUNTER MORE MOISTURE MOVING UP FROM THE
GULF. THIS IS IN GOOD AGREEMENT WITH THE THE NUMBER OF LREF MEMBERS
THAT ARE PRODUCING PRECIPITATION. THE NBM IQR DOES INCREASE FROM 2-
4 DEGREES LATE THIS WEEK TO TO 8-10 DEGREES BY MONDAY AND TUESDAY
WHICH DOES INDICATE THERE IS SOME SPREAD IN THE MODEL GUIDANCE
DURING THIS TIMEFRAME. HOWEVER, BUT IT DOES LOOK LIKE THIS WILL BE
ALL RAIN AS THE NUMBER THE LREF MEMBERS PRODUCING SNOW IS NOW <10%.
HIGHS WILL BE MAINLY IN THE 40S.
BRITT
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1014 PM CST TUE DEC 17 2024
SHOWERS HAVE BLOSSOMED ALONG A WARM FRONT DRAPED JUST SOUTH OF THE
ST. LOUIS AND CENTRAL MISSOURI TERMINALS. RIGHT ON THE NOSE OF A
LOW-LEVEL JET, TAPPING INTO VERY WEAK INSTABILITY, A THUNDERSTORM
DID INDEED DEVELOP AND IMPACT KCPS. OTHERWISE, PRECIPITATION IS
DEVELOPING AS EXPECTED. CIGS, HOWEVER, ARE TAKING LONGER TO DROP
THAN FORECAST. WHILE MVFR CONDITIONS EXIST JUST SOUTH OF THE WARM
FRONT, LOW-END VFR CONDITIONS REMAIN IN PLACE AT THE TAF SITES.
CONDITIONS ARE STILL FORECAST TO DEGRADE, THOUGH THE MVFR ONSET
WAS PUSHED BACK A FEW HOURS INTO THE EARLY MORNING. KUIN WILL
REMAIN VFR AND LARGELY DRY TONIGHT, HOWEVER A MID-LEVEL WAVE
ACROSS IOWA IS LOOKING INCREASINGLY LIKELY TO DRAW MVFR CONDITIONS
INTO EASTERN MISSOURI AND WESTERN ILLINOIS DURING THE EARLY
AFTERNOON ON WEDNESDAY. AS SUCH, A WINDOW OF MVFR WAS ADDED AFTER
A BRIEF IMPROVEMENT IN THE LATE MORNING. WITH HIGH PRESSURE
SLOWLY MOVING IN AFTER THIS, VFR CONDITIONS SHOULD RETURN BY THE
END OF THE FORECAST PERIOD.
MRB
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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