794
FXUS63 KLSX 160339
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1039 PM CDT MON SEP 15 2025
KEY MESSAGES
- SEASONABLY HOT WEATHER IS EXPECTED TO CONTINUE THROUGH THURSDAY
BEFORE SOME RELIEF OCCURS BY THE END OF THE WEEK.
- THERE IS AT LEAST A LOW CHANCE OF THUNDERSTORMS ACROSS PARTS OF
THE AREA EACH DAY, WITH THE BEST CHANCE (30-60%) ACROSS MUCH OF
THE AREA THURSDAY NIGHT INTO SATURDAY.
SHORT TERM
(THROUGH LATE TUESDAY AFTERNOON)
ISSUED AT 222 PM CDT MON SEP 15 2025
ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS PORTIONS
OF CENTRAL AND SOUTHEAST MISSOURI OVER THE PAST FEW HOURS
ALONG/WEST OF A BACKDOOR COLD FRONT. VERY WEAK DEEP-LAYER SHEAR
SUGGESTS THE VAST MAJORITY OF THESE STORMS WILL BE BRIEF/WEAK AS
DOWNDRAFTS QUICKLY WEAKEN THEIR OWN UPDRAFTS. HOWEVER, THERE MAY
BE A STRONGER STORM OR TWO THAT YIELD SOME STRONG WIND GUSTS VIA
MICROBURSTS GIVEN STEEP LOW-LEVEL LAPSE RATES AND HIGH DCAPE
VALUES CURRENTLY SHOWN ON THE LATEST SPC MESOANALYSIS.
THE COVERAGE AND STRENGTH OF ACTIVITY SHOULD GRADUALLY DECREASE
THROUGH THE EVENING HOURS AS DIURNAL INSTABILITY ABATES AFTER
SUNSET. DID LINGER POPS IN CENTRAL MISSOURI A BIT LONGER (CLOSER TO
MIDNIGHT) THAN PREVIOUSLY FORECAST DUE TO SOME WEAK LOW-LEVEL
MOISTURE CONVERGENCE AND THE FACT THAT ACTIVITY LAST NIGHT ALSO
PERSISTED MUCH LONGER THAN ANTICIPATED.
TUESDAY LOOK SIMILAR TO THIS AFTERNOON, THOUGH THE BACKDOOR COLD
FRONT SHOULD BE FURTHER TO THE WEST. THIS MEANS THAT THE THREAT FOR
ISOLATED SHOWERS AND THUNDERSTORMS SHOULD ALSO SHIFT MORE INTO PARTS
OF CENTRAL/NORTHEAST MISSOURI, WITH MORE STABLE (LESS HUMID) AIR TO
THE EAST. HIGH TEMPERATURES ARE EXPECTED TO REACH INTO THE LOW 90S,
OR ABOUT 10 DEGREES ABOVE NORMAL FOR THE DATE.
GOSSELIN
LONG TERM
(TUESDAY NIGHT THROUGH NEXT MONDAY)
ISSUED AT 222 PM CDT MON SEP 15 2025
(TUESDAY NIGHT - WEDNESDAY NIGHT)
THERE IS LITTLE/NO CHANGE IN THE PATTERN THROUGH MIDWEEK WITH A
SKINNY MID/UPPER LEVEL RIDGE ACROSS THE MISSISSIPPI VALLEY. THE
REMNANT BACKDOOR COLD FRONT LOOKS EVEN MORE AMBIGUOUS/WASHED OUT BY
WEDNESDAY THOUGH, SO WEDNESDAY IS MORE LIKELY TO BE COMPLETELY DRY
EVERYWHERE. TEMPERATURES ARE EXPECTED TO TOP OUT ON WEDNESDAY IN THE
LOW 90S ONCE AGAIN, WITH MILD OVERNIGHT LOWS EACH NIGHT (60S).
(THURSDAY - NEXT MONDAY)
THE STAGNANT PATTERN BEGINS TO BREAKDOWN LATE THURSDAY/THURSDAY
NIGHT AS A MIDLEVEL SHORTWAVE TROUGH MOVES OUT OF THE SOUTHERN
PLAINS. THIS FEATURE COMBINED WITH INCREASING LOW-LEVEL MOISTURE
CONVERGENCE SHOULD YIELD AT LEAST SCATTERED SHOWERS AND
THUNDERSTORMS BY THURSDAY EVENING ACROSS CENTRAL AND NORTHEAST
MISSOURI. BEFORE THE STORM CHANCES INCREASE LATE IN THE DAY (AND
ASSOCIATED CLOUD COVER), ONE LAST HOT DAY FOR MID SEPTEMBER IS IN
STORE WITH HIGHS PREDOMINANTLY IN THE LOW 90S.
THE SYNOPTIC PATTERN FOR LATE THIS WEEK THROUGH AT LEAST THIS
WEEKEND SHOWS A MIDLEVEL CLOSED LOW QUASI-STATIONARY OVER THE
PLAINS, WITH A WEAK COLD FRONT SOMEWHERE OVER THE CWA. THIS LOOKS
LIKE A PATTERN WHICH SHOULD BE CONDUCIVE TO MULTIPLE ROUNDS OF
SHOWERS AND THUNDERSTORMS, LIKELY BEST TIMED WITH INDIVIDUAL
VORTICITY MAXIMA ROTATING CYCLONICALLY AROUND THE CLOSED MIDLEVEL
LOW. TIMING THESE INDIVIDUAL FEATURES THIS FAR OUT IS NEARLY
IMPOSSIBLE. THEREFORE, IT BECOMES VERY DIFFICULT TO HAVE ANY PERIOD
OF TIME WITH LIKELY POPS, BUT I WOULD NOT BE SURPRISED TO SEE POPS
INCREASE FOR MULTIPLE PERIODS BETWEEN FRIDAY AND NEXT MONDAY AS THE
SPREAD IN TIMING OF THESE INDIVIDUAL WAVES DECREASES.
THERE ALSO SHOULD BE AT LEAST SOME TYPE OF DIURNAL COMPONENT TO THE
POPS , WHEREBY POPS ARE MAXIMIZED IN THE AFTERNOON HOURS WHEN
DAYTIME INSTABILITY IS HIGHEST. HOWEVER, DETERMINISTIC MODEL
GUIDANCE ALSO SHOWS AT LEAST SOME LOW-LEVEL MOISTURE CONVERGENCE
EACH NIGHT, WITH THE MORE ROBUST SIGNAL (AT LEAST RIGHT NOW) ON
SATURDAY NIGHT. WHILE THERE IS STILL QUITE A BIT OF UNCERTAINTY AS
TO HOW WIDESPREAD AND BENEFICIAL RAIN WILL BE, IT IS CERTAINLY THE
BEST LOOKING PATTERN FOR RAINFALL MOST OF THE AREA HAS SEEN IN AT
LEAST SEVERAL WEEKS (IF NOT SINCE MID/LATE JULY!). PROBABILITIES
FROM THE LREF FOR AT LEAST 0.50" OF RAIN ENDING NEXT MONDAY ARE IN
THE 50-90% (EAST TO WEST) RANGE, WITH CHANCES OF 1.00"+ BETWEEN 30
AND 50%.
TEMPERATURE WISE, THERE IS HIGH CONFIDENCE IN MILD (ABOVE NORMAL)
LOWS CONTINUING THROUGH THE PERIOD WITH HIGH TEMPERATURES COOLING
BACK CLOSER TO NORMAL. THE SPREAD IN THE INTER-QUARTILE RANGE IS
HIGHER FOR HIGH TEMPERATURES DUE TO UNCERTAINTY WITH PRECIPITATION.
MORE WIDESPREAD SHOWERS AND THUNDERSTORMS COULD REALLY HAMPER HIGH
TEMPERATURES, WITH THE 25TH PERCENTILE SLIGHTLY BELOW NORMAL (MID TO
UPPER 70S). COMPARE THAT TO THE 75TH PERCENTILE (MID TO UPPER 80S),
WHICH WOULD BE ABOUT 5 DEGREES ABOVE NORMAL. THOSE READINGS WOULD BE
POSSIBLE WITH MORE SUNSHINE/LESS CLOUD COVER AND ASSOCIATED RAIN
CHANCES.
GOSSELIN
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1035 PM CDT MON SEP 15 2025
WHILE VFR FLIGHT CONDITIONS ARE FORECAST FOR THE LOCAL TERMINALS
THROUGH THE TAF PERIOD, THERE IS A LOW CHANCE FOR IMPACTS AT KCOU
AND KJEF AT TIMES. FIRST, THERE IS A LOW CHANCE FOR FOG AT THESE
TWO TERMINALS GIVEN AREA RAINFALL THIS PAST EVENING. THE BEST
SIGNAL FOR THIS FOG IS SOUTH OF THESE TWO TERMINALS, BUT BRIEF,
MINOR IMPACTS CAN'T BE RULED OUT NEAR SUNRISE. TUESDAY AFTERNOON,
THERE IS A ANOTHER LOW CHANCE FOR SHOWERS AND THUNDERSTORMS, BUT
CONFIDENCE IS CURRENTLY HIGHER THAT THIS THREAT WILL REMAIN JUST
TO THE WEST OF KCOU AND KJEF.
ELMORE
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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