653
FXUS63 KLSX 181710
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1110 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 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1104 AM CST WED DEC 18 2024
THE MAIN SOURCE OF IMPACTS AT ALL LOCAL TERMINALS THIS FORECAST
PERIOD IS AN AREA OF OVERCAST TO BROKEN STRATUS MOVING SOUTHWARD
ACROSS THE REGION. UPSTREAM OBSERVATIONS SHOW LARGER BREAKS IN
THIS STRATUS DECK EXPAND AND CONTRAST WITH TIME, LEADING TO
UNCERTAINTY IN HOW CONSISTENTLY IMPACTS WILL PREVAIL LATER IN THE
AFTERNOON AND EARLY THIS EVENING. A COUPLE HOURS OF VFR FLIGHT
CONDITIONS ARE POSSIBLE AT ALL LOCAL TERMINALS LATER THIS
AFTERNOON AND EARLY THIS EVENING IF THESE BREAKS IN THE STRATUS
ARE ABLE TO MAKE IT IN TO PORTIONS OF THE REGION. EVEN IF STRATUS
IS ABLE TO CLEAR FOR SOME TERMINALS THIS EVENING, COOLING
TEMPERATURES OVERNIGHT WILL LIKELY ALLOW FOR STRATUS TO REDEVELOP
OR EXPAND THROUGH THE EARLY MORNING HOURS. VFR FLIGHT CONDITIONS
ARE EXPECTED TO RETURN TOMORROW MORNING AS WINDS BECOME
INCREASINGLY SOUTHERLY.
ELMORE
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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