835
FXUS63 KLSX 291950
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
250 PM CDT SAT MAR 29 2025
KEY MESSAGES
- A FEW SEVERE THUNDESTORMS ARE POSSIBLE LATE TONIGHT AND EARLY
SUNDAY MORNING OVER PARTS OF CENTRAL AND NORTHEAST MISSOURI INTO
WEST CENTRAL ILLINOIS. DAMAGING WINDS WILL BE THE PRIMARY THREAT.
- SEVERE THUNDERSTORMS ARE LIKELY ON SUNDAY AFTERNOON WITH LARGE
HAIL, DAMAGING WINDS, AND A FEW TORNADOES OVER SOUTHEAST AND EAST
CENTRAL MISSOURI AS WELL AS SOUTHWEST AND SOUTH CENTRAL ILLINOIS.
SHORT TERM
(THROUGH LATE SUNDAY NIGHT)
ISSUED AT 249 PM CDT SAT MAR 29 2025
AN AREA OF RAIN HAS BEEN SLOW TO MOVE OUT OF THE CWA THIS AFTERNOON
AHEAD OF A WEAK MID-LEVEL TROUGH MOVING THROUGH THE MID MISSSISSIPPI
RIVER VALLEY. THIS TROUGH WILL PROGESS EASTWARD THIS LATE AFTERNOON
ALLOWING THE RAIN TO EXIT THE AREA. WE WILL THEN FOCUS TO THE WEST
LATE TONIGHT WHEN SEVERE THUNDERSTORMS WILL LIKELY GROW UPSCALE INTO
A LINE AND ENTER CENTRAL MISSOURI AFTER 3 AM. THIS QLCS WILL STILL
HAVE THE POTENTIAL TO PRODUCE SOME DAMAGING WIND GUSTS AS IT ENTERS
THE CWA BEFORE IT GRADUALLY WEAKENS AS IT MOVES TO THE NORTHEAST
TOWARD THE MISSISSIPPI RIVER TOWARD AROUND SUNRISE.
THIS FIRST ROUND OF SHOWERS AND THUNDERSTORMS WILL HAVE AN IMPACT ON
HOW ADDITIONAL THUNDERSTORMS DEVELOP AND HOW SEVERE THEY MAY BE
LATER IN THE DAY ON SUNDAY. IF THE MORNING ROUND OF STORMS LINGER
AROUND LONGER AND PUSHES AN OUTFLOW BOUNDARY FARTHER SOUTH, THEN
LESS OF THE CWA WILL LIKELY SEE ANY SEVERE WEATHER TOMORROW. IF
THIS MORNING ROUND MOVES THROUGH QUICKLY AND AFFECTS LESS OF THE
CWA, THEN THERE WILL BE MORE CHANCE THAT CONVECTIVE INITITAION WILL
OCCUR FARTHER TO THE NORTHWEST AND WILL AFFECT MORE OF THE CWA
INCLUDING THE ST. LOUIS METRO AREA. AT THIS POINT, TWEAKED THE
GOING FORECAST USING A BLEND OF THE LATEST HRRR/HREF FORECAST WHICH
WOULD FAVOR DEVELOPMENT OF THUNDERSTORMS BY EARLY AFTERNOON OVER
PART OF SOUTHEAST AND EAST CENTRAL MISSOURI INTO SOUTHWEST AND SOUTH
CENTRAL ILLINOIS WITH STORMS EXITING THE AREA BY LATE EVENING. THE
CAMS ARE SHOWING A SMALL WINDOW FOR DISCRETE CELLS INTIALLY OVER THE
CWA BEFORE THE STORMS FORM INTO A LINE. HAZARDS STILL INCLUDE
DAMAGING WINDS, LARGE HAIL, AND A FEW TORNADOES.
DID DROP HIGHS A FEW DEGREES TOMORROW, ESPECIALLY IN THE NORTHWEST
HALF WHERE I EXPECT MORE RAIN AND CLOUDS TO MAKE AN IMPACT ON
TEMPERATURES.
BRITT
LONG TERM
(MONDAY THROUGH NEXT SATURDAY)
ISSUED AT 249 PM CDT SAT MAR 29 2025
THE ACTIVE PATTERN WILL CONTINUE INTO NEXT WEEK AS MODEL GUIDANCE IS
SHOWING ANOTHER STRONG TROUGH MOVING THROUGH THE MIDWEST ON
WEDNESDAY. THE CLUSTER ANALYSIS IS STILL POINTING AT SOME TIMING
DIFFERENCES BETWEEN THE ENSEMBLE SOLUTIONS AT THIS POINT, BUT THERE
REMAINS ENOUGH AGREEMENT TO KEEP 70-90% POPS FOR SHOWERS AND SOME
THUNDERSTORMS TUESDAY NIGHT INTO WEDNESDAY NIGHT. WE WILL NEED TO
CONTINUE TO MONITOR WEDNESDAY FOR A FEW STRONG TO SEVERE
THUNDERSTORMS AS THE LREF HAS JOINT PROBABILITIES OF MUCAPE >500
J/KG AND 0-500MB BULK SHEAR OF >30 KTS BETWEEN 30-50%. THE RAIN
POTENTIAL WILL NOT CLEAR OUT LATE WEEK AS THE UPPER PATTERN WILL
TURN WEST-SOUTHWESTERLY BEHIND THE UPPER TROUGH. THIS WILL CAUSE THE
ATTENDANT COLD FRONT TO HOLD UP JUST SOUTH OF THE CWA THURSDAY INTO
NEXT SATURDAY KEEPING A CHANCE (30-60%) OF ADDITIONAL SHOWERS AND
THUNDERSTORMS DURING THIS PERIOD.
MONDAY AND TUESDAY ARE EXPECTED TO BE COOLER BEHIND SUNDAY'S FRONT
WITH HIGHS ONLY IN THE 50S AND 60S WITH WARMUP ON WEDNESDAY AHEAD OF
THE COLD FRONT WITH TEMPERATURES WARMING BACK INTO THE 70S. I HAVE
FAIRLY GOOD CONFIDENCE IN THE TEMPERATURES ON MONDAY AND TUESDAY AS
THE NBM IQR AT ST. LOUIS IS ONLY 5 DEGREES BEFORE INCREASING TO 8-10
DEGREES THE REST OF THE WEEK GIVEN THE UNCERTAINTY IN THE UPPER FLOW
PATTERN.
BRITT
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1247 PM CDT SAT MAR 29 2025
THE LIGHT RAIN HAS MOVED OUT OF THE ST. LOUIS AREA AIRPORTS AND
MAINLY DRY CONDITIONS ARE NOW EXPECTED THROUGH THIS EVENING. OTHER
THAN SOME LOW VFR CEILINGS EARLY THIS EVENING AT COU/JEF/UIN,
MAINLY MVFR CEILINGS ARE EXPECTED DURING THE PERIOD WITH CEILINGS
FALLING BELOW 2000 FEET AGL BY LATE TONIGHT. SHOWERS AND
THUNDERSTORMS WILL MOVE INTO COU/JEF AROUND 08Z AND MOVE EAST INTO
UIN/STL/SUS/CPS BY 10-12Z. SOME OF THE HEAVIER SHOWERS AND
THUNDERSTORMS WILL BE CAPABLE OF REDUCING CEILINGS AND
VISIBILITIES TO IFR CONDITIONS AND PRODUCE WIND GUSTS OVER 35
KNOTS. WINDS WILL BE OUT OF THE SOUTH TODAY, BUT WILL TURN OUT OF
THE SOUTHWEST AND WEST ON SUNDAY MORNING. THERE IS CHANCE OF
ADDITIONAL THUNDERSTORMS EARLY ON SUNDAY AFTERNOON, BUT I HAVE NOT
INCLUDED THEM IN THE STL TAF AS THEY MAY DEVELOP JUST TO THE
SOUTH AND EAST OF THE TERMINAL.
BRITT
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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