412
FXUS63 KLSX 181149
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
649 AM CDT WED JUN 18 2025
KEY MESSAGES
- SEVERE THUNDERSTORMS REMAIN POSSIBLE THIS AFTERNOON AND
EVENING, PARTICULARLY OVER SOUTHEAST MISSOURI AND SOUTHWEST
ILLINOIS.
- HEAT INDEX VALUES MAY CLIMB ABOVE 100 DEGREES STARTING FRIDAY
AND LAST INTO EARLY NEXT WEEK.
SHORT TERM
(THROUGH LATE THURSDAY AFTERNOON)
ISSUED AT 258 AM CDT WED JUN 18 2025
LATEST RADAR MOSAIC IS SHOWING SCATTERED THUNDERSTORMS DEVELOPING
OVER CENTRAL MISSOURI WITH AN ORGANIZED MCS MOVING EAST ACROSS
SOUTHERN MISSOURI AND NORTHERN ARKANSAS. WHILE THE CAMS HAVE THE
MCS STAYING SOUTH OF THE CWA, THEY DO SHOW A MCV MOVING NORTHEAST
THAT WILL HELP GENERATE ADDITIONAL SHOWER AND THUNDERSTORMS, MAINLY
ACROSS CENTRAL AND NORTHEAST MISSOURI INTO WEST ILLINOIS EARLY THIS
MORNING BETWEEN 5 AND 9 AM. THE OUTFLOW FROM THIS ACTIVITY MAY
VERY WELL EITHER PUSH INTO THE EASTERN AND SOUTHERN PARTS OF THE
CWA THIS MORNING, OR PERHAPS OUT OF THE CWA ALTOGETHER DEPENDING
ON THE STRENGTH OF THE OUTFLOW BOUNDARY. IF THE BOUNDARY DOES STAY
IN THE THE CWA, IT WILL ACT AS A FOCUS FOR ADDITIONAL
THUNDERSTORM ACTIVITY AS LATEST RUNS OF THE HRRR IS SHOWING SOME
ADDITIONAL DEVELOPMENT OVER THE EASTERN CWA LATE THIS MORNING IN
THE FORM OF DISCRETE CELLS. FORECAST SOUNDINGS FROM THE RAP AT SLO
AND FAM THIS AFTERNOON ARE SHOWING MLCAPES OF 1000-2000 J/KG WITH
DEEP LAYER SHEAR 30-40 KNOTS WHICH WILL BE ENOUGH TO SUPPORT
ORGANIZED MULTI-CELLS AND PERHAPS SUPERCELLS, WITH THE MAIN
THREAT BEING DAMAGING WINDS WITH LARGE HAIL AND TORNADOES ALSO
POSSIBLE.
THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL COME TO AN END FROM
NORTHWEST TO SOUTHEAST AS FRONT CURRENTLY EXTENDING FROM IOWA INTO
NEBRASKA WILL MOVE SOUTHEAST ACROSS THE AREA TONIGHT. DRY WEATHER
IS EXPECTED ON THURSDAY AS AN UPPER RIDGE BEGINS TO BUILD IN FROM
THE PLAINS.
BRITT
LONG TERM
(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 258 AM CDT WED JUN 18 2025
THE LREF HAS THE AFOREMENTIONED RIDGE BUILDING OVER THE MIDWEST
BRINGING DRY AND WARM WEATHER LATE WEEK INTO THE WEEKEND. THE NBM
IS SHOWING IQR OF ONLY 2-4 DEGREES AT STL FROM FRIDAY THROUGH
MONDAY WITH HIGHS IN THE LOWER TO MIDDLE 90S. WITH DEWPOINTS
FORECAST IN THE 70S, HEAT INDICES CLIMBING ABOVE 100 DEGREES SEEM
REASONABLE WITH THE LREF PROBABILITIES AOA 50% OVER PARTS OF THE
AREA ON SATURDAY AND SUNDAY AFTERNOONS.
BRITT
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 637 AM CDT WED JUN 18 2025
SHOWERS/ISOLATED THUNDERSTORMS WITH MVFR CEILINGS AND VISIBILITES
WILL AFFECT UIN/STL/SUS/CPS THROUGH 15Z. THERE MAY BE A BRIEF
BREAK IN RAIN CHANCES BEFORE A COLD FRONT WILL MOVE INTO THE AREA
BRINGING AN ADDITIONAL CHANCE (PROB30) THIS AFTERNOON, MAINLY
BETWEEN 17-22Z. ANY THUNDERSTORMS WILL HAVE THE POTENTIAL TO
PRODUCE MVFR/IFR CEILINGS AND VISIBILITES IN BRIEF HEAVY RAIN,
HAIL, AND WIND GUSTS OVER 35 KNOTS. THERE IS ALSO A LOW POTENTIAL
FOR FOG WHICH COULD BRING MVFR/IFR VISIBILITIES AFTER 06Z TONIGHT,
BUT CONFIDENCE IS TOO LOW TO INTRODUCE IT THIS FAR OUT.
BRITT
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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