749
FXUS63 KLSX 280839
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
339 AM CDT TUE OCT 28 2025
KEY MESSAGES
- RAIN WILL OVERSPREAD THE AREA FROM LATE THIS AFTERNOON INTO THIS
EVENING. RAIN IS EXPECTED TO END FROM NORTHWEST TO SOUTHEAST ON
WEDNESDAY.
- FORECAST RAINFALL AMOUNTS RANGE FROM AROUND 4/10 OF AN INCH IN
WEST CENTRAL ILLINOIS TO ROUND 1 3/4 INCHES IN SOUTHEAST
MISSOURI.
- DRY WEATHER WITH SEASONABLY COOL TEMPERATURES IS EXPECTED FOR
THE REST OF THE WEEK.
SHORT TERM
(THROUGH WEDNESDAY NIGHT)
ISSUED AT 329 AM CDT TUE OCT 28 2025
A STRONG NEGATIVELY TILTED SHORT WAVE TROUGH IS DIGGING INTO THE
GREAT PLAINS THIS MORNING. THE OPEN WAVE IS FORECAST TO CLOSE OFF
OVER THE EAST CENTRAL PLAINS LATE THIS AFTERNOON OR EARLY THIS
EVENING. AS THIS HAPPENS IT WILL FORCE LOW LEVEL CYCLOGENESIS OVER
THE LOWER AND MID MISSISSIPPI VALLEY RESULTING IN A CLOSED LOW
DEVELOPING IN THE VICINITY OF THE MISSOURI BOOTHEEL BY AROUND 06Z
TONIGHT. THE STACKED LOW PRESSURE SYSTEM WILL THEN MOVE SLOWLY
EASTWARD INTO THE TENNESSEE VALLEY WEDNESDAY AND PHASE WITH ANOTHER
TROUGH OVER THE MID ATLANTIC AND NORTHEASTERN U.S.
THIS ALL BOILS DOWN TO ANOTHER PERIOD OF RAIN FOR THE FORECAST AREA.
THERE MAY BE A FEW SPRINKLES OR AREAS OF LIGHT RAIN THIS MORNING.
GUIDANCE SHOWS THE DEVELOPING LOW WILL PRODUCE WEAK LOW LEVEL
MOISTURE CONVERGENCE, MAINLY EAST OF THE MISSISSIPPI RIVER DURING
THE MORNING. MOISTURE CONVERGENCE WILL STRENGTHEN THIS AFTERNOON
AND EVENING AS THE CLOSED LOW DEEPENS PRODUCING STEADIER AND MORE
WIDESPREAD RAIN ACROSS THE AREA. MODELS SHOW A STEADY STREAM OF LOW
LEVEL MOISTURE WRAPPING INTO THE SYSTEM, FIRST FROM THE GULF TO THE
SOUTH TODAY, AND THEN FROM THE EAST TONIGHT AND WEDNESDAY AS THE LOW
LEVEL COLD FRONT MOVES THROUGH THE LOWER MISSISSIPPI VALLEY INTO THE
GULF. RAIN WILL END FROM NORTHWEST TO SOUTHEAST ON WEDNESDAY AS THE
LOW MOVES EAST, AWAY FROM THE AREA AND DRIER LOW LEVEL AIR IS PULLED
IN FROM THE NORTH BEHIND IT. THIS WILL BE ANOTHER PERIOD OF
BENEFICIAL RAIN DESPITE IT LASTING FOR AS MUCH AS 18-24 HOURS
ACROSS PARTS OF SOUTHEAST MISSOURI AND SOUTHWEST ILLINOIS. RAINFALL
RATES ARE NOT EXPECTED TO BE EXCESSIVE, AND ACCUMULATIONS ARE NOT
EXPECTED TO EXCEED 1 INCH IN ANY 6 HOUR PERIOD (IN MOST CASES WELL
UNDER THAT). TEMPERATURES THROUGH THE PERIOD WILL REMAIN COOL DUE TO
CLOUDS AND PRECIP WITH HIGHS TODAY AND WEDNESDAY MAINLY IN THE MID
TO UPPER 50S AND LOWS IN THE MID TO UPPER 40S TODAY, DROPPING TO THE
35-40 DEGREE RANGE WEDNESDAY NIGHT BEHIND THE COLD FRONT.
CARNEY
LONG TERM
(THURSDAY THROUGH MONDAY)
ISSUED AT 329 AM CDT TUE OCT 28 2025
THE REMAINDER OF THE FORECAST LOOKS RELATIVELY QUIET. THE OVERALL
WEATHER PATTERN REMAINS HIGHLY AMPLIFIED AT LEAST THROUGH THE
WEEKEND WITH LONG WAVE TROUGHING OVER THE EASTERN 1/2 OF THE CONUS
AND RIDGING OVER THE WEST. THIS WILL KEEP OUR SEASONABLY COOL
STREAK GOING WITH TEMPERATURES NEAR, TO A FEW DEGREES BELOW NORMAL.
ANOTHER SHORT WAVE TROUGH WILL DROP FROM THE NORTHERN PLAINS INTO
THE MID MISSISSIPPI VALLEY FRIDAY NIGHT INTO SATURDAY. THE SURFACE
COLD FRONT ASSOCIATED WITH THE WAVE PUSHES THROUGH EARLY SATURDAY
MORNING, AND COLD ADVECTION FROM LOW LEVEL NORTHWEST FLOW WILL
PRODUCE ANOTHER DAY WITH HIGHS 5 OR MORE DEGREES BELOW NORMAL,
LIKELY THE COOLEST DAY OF THE MEDIUM RANGE. LREF INTERQUARTILE RANGE
OF HIGHS AT STL ON SATURDAY IS ONLY 3 DEGREES (52-55) SO CONFIDENCE
IN THESE COOL TEMPERATURES IS HIGH. STRONG PVA AND MODEST MID-LEVEL
FRONTOGENESIS ASSOCIATED WITH THE WAVE MAY PRODUCE SOME VERY LIGHT
RAIN OR SPRINKLES, THOUGH CURRENT INDICATIONS ARE THAT MID-LEVEL
MOISTURE WILL BE LACKING. INDEED, LESS THAN 20% OF THE LREF MEMBERS
PRODUCE ACCUMULATING PRECIP WITH THIS WAVE. HOWEVER, A 15-20 PERCENT
CHANCE IS WARRANTIED AS THE WAVE PASSES SATURDAY NIGHT GIVEN THE
UNCERTAINTIES THIS FAR OUT. TEMPERATURES MODERATE A BIT SUNDAY AND
MONDAY AS COLD ADVECTION CEASES AND A CLEARER SKY ALLOWS FOR MORE
INSOLATION DURING THE DAY.
CARNEY
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 956 PM CDT MON OCT 27 2025
EXTENSIVE CLOUD COVER PERSISTS ACROSS THE REGION WITH CEILINGS
VARYING FROM NORTH TO SOUTH. NORTHERN AREAS INCLUDING QUINCY HAVE
REMAINED VFR WHILE SOUTHERN AREAS HAVE MUCH MORE EXTENSIVE IFR
CEILINGS. METRO ST LOUIS AND CENTRAL MO HAVE BEEN ON THE EDGE OF
THE LOWER CEILINGS AND HAVE FAVORED VFR OR MVFR CONDITIONS THE
LAST SEVERAL HOURS. IT IS POSSIBLE THAT CEILINGS LOWER OVERNIGHT
INTO TUESDAY MORNING, BUT A LOW LEVEL DRY EASTERLY FLOW MAY
COUNTERACT THIS TO SOME DEGREE AND KEEP CEILINGS A BIT HIGHER.
MVFR CEILINGS LIKELY PERSIST THROUGH THE DAY ON TUESDAY WITH RAIN
ARRIVING FROM THE WEST AROUND DURING THE EVENING. LOWER CEILINGS
AND SOME VISIBILITY REDUCTIONS MAY ACCOMPANY THE INCOMING RAIN.
KIMBLE
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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