734
FXUS63 KLSX 271736
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1236 PM CDT MON OCT 27 2025
KEY MESSAGES
- A ROUND OF WIDESPREAD SOAKING RAINFALL IS FORECAST TUESDAY INTO
WEDNESDAY. THE PROBABILITY OF AT LEAST 0.5" IS NOW 80% ACROSS A
MAJORITY OF THE AREA.
- THE COOLEST AIR OF THE SEASON YET IS EXPECTED STARTING
WEDNESDAY, CONTINUING THROUGH AT LEAST FRIDAY.
SHORT TERM
(THROUGH TUESDAY NIGHT)
ISSUED AT 228 AM CDT MON OCT 27 2025
THE UPPER LOW RESPONSIBLE FOR OUR RECENT RAINFALL CAN BE SEEN IN
WATER VAPOR IMAGERY SPINNING ACROSS THE MID SOUTH THIS MORNING,
THOUGH IT IS BECOMING MORE DEFUSE COMPARED TO ITS APPEARANCE IN DAYS
PAST. WITH IT DEPARTING THE AREA AND WEAKENING, THE MORE PERSISTENT
RAINFALL WILL CONTINUE TO WIND DOWN THROUGH THE MORNING HOURS FROM
WEST TO EAST. DESPITE THE END OF THE MORE PERSISTENT RAIN, LOW-LEVEL
MOISTURE WILL REMAIN PLENTIFUL, LEADING TO LOW STRATIFORM ACROSS
A MAJORITY OF THE CWA THROUGH THE DAY. THERE IS A WEAK SIGNAL FOR
PATCHY LIGHT RAIN/DRIZZLE ACROSS SOUTHEASTERN MISSOURI AND
SOUTHWESTERN ILLINOIS THROUGH THE DAY, BUT CONFIDENCE IN THIS
OCCURRING IS VERY LOW RIGHT NOW.
THIS DREARY WEATHER WILL CONTINUE INTO TUESDAY, AS AN UPPER-LEVEL
TROUGH DIGS INTO THE MIDDLE MISSISSIPPI VALLEY. THIS TROUGH WILL BE
PUSHING A STRONG COLD FRONT AND ASSOCIATED RAINFALL ACROSS THE
PLAINS TOWARD THE CWA THROUGH THE DAY, WITH IT ENTERING CENTRAL AND
NORTHEASTERN MISSOURI SOMETIME TUESDAY EVENING. AS IT DOES SO, A
SHORTWAVE ROUNDING THE BASE OF THE TROUGH WILL INDUCE CYCLOGENESIS
ALONG THE FRONT EITHER OVER OR VERY CLOSE TO THE CWA. THIS WILL
SUPPORT RAINFALL COVERAGE AND INTENSITY INCREASING OVER THE
REGION TUESDAY NIGHT AS A WARM CONVEYOR BELT RAMPS UP ALONG THE
EASTERN AND NORTHER PERIPHERY OF THE DEEPENING SURFACE LOW. WITHIN
THE CONVEYOR BELT, INSTABILITY AND DYNAMIC LIFT MAY SUPPORT
EMBEDDED THUNDERSTORMS THAT WOULD HELP INCREASE RAINFALL RATES
LOCALLY, BUT SEVERE WEATHER AND/OR FLASH FLOODING IS NOT
ANTICIPATED.
ELMORE
LONG TERM
(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 228 AM CDT MON OCT 27 2025
GUIDANCE CONSENSUS IS THAT AT THE START OF THE DAY ON WEDNESDAY, THE
UPPER-LEVEL TROUGH WILL BE IN THE PROCESS OF CUTTING OFF OVER THE
SOUTHEASTERN US AS IT INTERACTS WITH ANOTHER UPPER LOW OVER THE
NORTHEAST AND UNDERGOES FUJIWHARA INTERACTION. THE SENSIBLE
WEATHER THAT OCCURS WITH SUCH INTERACTION IS DIFFICULT TO FORECAST
ACCURATELY AT LEAD TIMES SUCH AS THIS DUE TO HOW SUBTLE
DIFFERENCES IN THE STRENGTH AND PHASING OF EACH LOW AND THE
SUBSEQUENT SYSTEM CAN CAUSE SIGNIFICANT DIVERGENCE AMONG GUIDANCE
SOLUTIONS. THEREFORE, EXACTLY HOW QUICKLY THE SURFACE LOW DEPARTS
THE REGION IS UNCERTAIN AT THIS TIME RANGE. A FASTER SOLUTION
SUPPORTS RAIN CHANCES DEPARTING THE CWA BY WEDNESDAY AFTERNOON AND
EVENING, WHILE A SLOWER SOLUTION WILL LEAD TO RAIN LINGERING
ACROSS PORTIONS OF THE CWA INTO WEDNESDAY NIGHT. BY THE TIME
RAINFALL WINDS DOWN, MUCH OF CWA WILL HAVE EXPERIENCED A WIDE-
SPREAD SOAKING RAIN. NBM PROBABILITIES HAVE INCREASED FOR AT LEAST
0.5" OF ACCUMULATION, WITH THE ENTIRE CWA SEEING AT LEAST AN 80%
CHANCE OF SUCH A THRESHOLD OR MORE.
REGARDLESS OF THE EXACT PHASING OF THE UPPER-LEVELS, CONFIDENCE IS
HIGH THAT THE CWA WILL BE ON THE COLD SIDE OF THE FRONT ON WEDNESDAY
AS DEEP NORTHERLY FLOW ADVECTS A SEASONABLY COOL AIR MASS INTO THE
REGION. CONFIDENCE IS ALSO HIGH THAT THIS AIR MASS WILL DELIVER
THE COOLEST AIR OF THE SEASON THUS FAR, WITH A STRONGER SIGNAL FOR
TROUGHING THROUGH THE END OF THE WORKWEEK SUPPORTING A RELATIVELY
PROLONGED PERIOD OF BELOW NORMAL TEMPERATURES. NBM-BASED
PROBABILITIES FOR TEMPERATURES FAILING TO WARM ABOVE 60 DEGREES IS
90% FOR WEDNESDAY AND THURSDAY, AND 60% FOR FRIDAY, WITH LOW TO
MID-50S FORECAST FOR HIGHS. WE'LL HAVE TO KEEP AN EYE OUT FOR
FROST POTENTIAL THROUGH THIS STRETCH, AS COOLER GUIDANCE SUPPORTS
LOWS IN THE MID-30S. AT THIS LEAD TIME, CONFIDENCE IS LOW IN WIND
SPEEDS AND CLOUD COVER, LEADING TO HIGH UNCERTAINTY IN THE THREAT
OF FROST. THE SPREAD IN TEMPERATURE FORECASTS AMONG ENSEMBLE
GUIDANCE INCREASES NOTABLY OVER THE WEEKEND AS GUIDANCE DIVERGES
ON THE PHASING OF A SHORTWAVE MOVING THROUGH THE CENTRAL CONUS,
WITH GUIDANCE SPLIT ON SHOWING TEMPERATURES GRADUALLY MODERATING
OR CONTINUING WITH COOLER THAN NORMAL VALUES.
ELMORE
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1230 PM CDT MON OCT 27 2025
PERIODS OF DRIZZLE ARE EXPECTED TO DISSIPATE EARLY THIS
AFTERNOON, LEAVING DRY CONDITIONS UNTIL AT LEAST TOMORROW MORNING.
WIDESPREAD RAIN IS EXPECTED TO NEAR CENTRAL MISSOURI TOMORROW, SO
ADDED PROB30S FOR THE END OF THE PERIOD.
MORE NOTABLY, PESKY STRATUS CONTINUES TO SIT ATOP THE CWA WITH THE
GRADIENT BETWEEN MVFR AND IFR SITTING BASICALLY RIGHT OVER THE ST.
LOUIS METROPOLITAN TERMINALS. FOR THIS REASON, CEILINGS MAY BOUNCE
BETWEEN SUB-1000 FT AND 1000-1500 FT UNTIL LATE TONIGHT WHEN IFR
CEILINGS SPREAD NORTH AGAIN. MODELS SUGGEST WIDESPREAD LIFR
OVERNIGHT, BUT HOLDING OFF ON LOCKING THAT IN UNTIL NEWER GUIDANCE
COMES IN.
JAJA
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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