306
FXUS63 KLSX 100522
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1222 AM CDT TUE MAR 10 2026
KEY MESSAGES
- NEAR RECORD-HIGH TEMPERATURES ARE POSSIBLE AGAIN ON TUESDAY.
- THERE IS A THREAT OF SEVERE THUNDERSTORMS ON TUESDAY, MAINLY IN
THE EVENING ACROSS NORTHEASTERN MO/WEST-CENTRAL IL, CONDITIONAL
ON THUNDERSTORMS INITIATING IN THE EVENING VERSUS OVERNIGHT.
- MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED
OVERNIGHT TUESDAY NIGHT INTO EARLY WEDNESDAY AFTERNOON WITH
TRANSITION TOWARD MORE OF A LOCALLY HEAVY RAINFALL THREAT.
SHORT TERM
(THROUGH LATE TUESDAY NIGHT)
ISSUED AT 243 PM CDT MON MAR 9 2026
LOW-LEVEL SOUTHERLY FLOW/WAA AND A LACK OF BOUNDARY LAYER DECOUPLING
WILL LEAD TO A VERY MILD NIGHT TONIGHT WITH LOW TEMPERATURES IN THE
UPPER 50S TO LOW-60S F ACROSS THE CWA, POSSIBLY SETTING THE STAGE
FOR BREAKING DAILY RECORD MAXIMUM LOW TEMPERATURES. THESE MILD
TEMPERATURES AND 850-HPA TEMPERATURES NEARING SEASONAL
CLIMATOLOGICAL MAXIMUMS WILL ASSIST TUESDAY IN BEING ANOTHER VERY
WARM DAY ACROSS THE AREA WITH HIGH TEMPERATURES ONCE AGAIN REACHING
THE MID-70S TO LOW-80S F, APPROACHING DAILY RECORDS. HOWEVER, WITH
INCREASING MOISTURE THERE SHOULD ALSO BE AREAS OF
STRATOCUMULUS/CUMULUS AND SOME MID-LEVEL CLOUDS THAT WILL AT LEAST
SLIGHTLY LIMIT INSOLATION AND KEEP THE ANOMALOUS 850-HPA
TEMPERATURES FROM DIRECTLY TRANSLATING TO SURFACE TEMPERATURES.
THE WARM AND MOISTURE AIRMASS ENTRENCHING THE CWA IN THE WARM SECTOR
WILL ALSO HELP BOLSTER SEASONABLY HIGH INSTABILITY DURING THE
AFTERNOON (MOST MODEL GUIDANCE AGREEING ON MLCAPE REACHING 1500 TO
3000 J/KG) ALONG WITH DEEP-LAYER SHEAR OF 35 TO 50 KT, PROVIDING
FAVORABLE CONDITIONS FOR SEVERE THUNDERSTORMS. THE MAIN POINT OF
UNCERTAINTY REMAINS THE AFOREMENTIONED 850-HPA TEMPERATURES LEADING
TO A CAPPING INVERSION, DELAYING THE DEVELOPMENT OF THUNDERSTORMS.
THE CAPPING INVERSION IS MOST LIKELY TO BE OVERCOME ACROSS
NORTHEASTERN MO AND WEST-CENTRAL IL NEAR A WEST-TO-EAST
WARM/STATIONARY FRONT LEADING A WEAK SURFACE LOW WITH A SUBTLE
APPROACHING UPPER-LEVEL SHORTWAVE TROUGH, BUT CAMS VARY BETWEEN
INITIATION AS EARLY AS 22Z AND AS LATE AS 06Z. IF THUNDERSTORMS CAN
DEVELOP IN THE CWA EARLIER IN THIS WINDOW WHEN INSTABILITY IS
GREATER, SUPERCELLS ARE AT LEAST INITIALLY EXPECTED, WITH THE MAIN
HAZARDS BEING VERY LARGE HAIL (STEEP LAPSE RATES AND LARGE AMOUNTS
OF CAPE IN THE HAIL GROWTH ZONE) AND TORNADOES. WITH 150 TO 200+
M2/S2 OF 0-1 KM SRH, A STRONG TORNADO IS POSSIBLE, PRIMARILY ALONG
THE FRONT WHERE THERE IS GREATER LOW-LEVEL HODOGRAPH CURVATURE.
ALTHOUGH FORCING IS WEAK DURING THE EVENING, DEEP-LAYER SHEAR WILL
BE NEARLY PARALLEL WITH THE FRONT, SUGGESTING STORM MERGERS AND
UPSCALE GROWTH COULD OCCUR WITH TIME, LEADING TO DAMAGING WINDS
BECOMING THE MAIN HAZARD. ALL OF THIS BEING SAID, THIS PERIOD OF
GREATER SEVERE THREAT IS SOMEWHAT CONDITIONAL, SINCE SOME CAMS/SHORT-
TERM MODELS ACTUALLY DELAY THUNDERSTORM INITIATION BEYOND THIS
PERIOD OF MORE FAVORABLE PARAMETER SPACE, WITH GREATER SUPPORT FOR
EARLIER INITIATION ACROSS CENTRAL/NORTH-CENTRAL IL.
COVERAGE OF SHOWERS AND THUNDERSTORMS WILL MORE CONFIDENTLY INCREASE
TUESDAY NIGHT AS UPSCALE GROWTH OCCURS ALONG THE WARM FRONT AND
APPROACHING COLD FRONT, THE LLJ STRENGTHENS, AND ADDITIONAL SHOWERS
AND THUNDERSTORMS POTENTIAL ENTER THE CWA FROM THE SOUTHERN OZARKS.
IT IS MOST LIKELY THAT OVERNIGHT THUNDERSTORMS WILL BE LARGELY
ELEVATED AS THE BOUNDARY LAYER STABILIZES AND INSTABILITY BECOMES
OVERTURNED. THAT BEING SAID, POCKETS OF GREATER INSTABILITY AND
CONSTRUCTIVE THUNDERSTORM INTERACTIONS COULD PROVIDE A LINGERING
MARGINAL SEVERE THREAT OF ISOLATED DAMAGING WINDS AND MARGINALLY
SEVERE HAIL. LOCALLY HEAVY RAINFALL COULD ALSO BECOME THE PRIMARY
HAZARD IN A FAVORABLE ENVIRONMENT WITH PW EXCEEDING THE 99TH
CLIMATOLOGICAL PERCENTILE AND WARM CLOUD DEPTHS AROUND 10 KFT, BUT
WHETHER OR NOT FLASH FLOOD OCCURS WILL COME DOWN TO THUNDERSTORM
EVOLUTION WITH WIND PROFILES AT LEAST SUPPORTIVE OF TRAINING AND
BACKBUILDING THUNDERSTORMS INTO THE LLJ. THE LATEST HREF QPF LPMM
HIGHLIGHTS NORTHEASTERN MO AND WEST-CENTRAL IL WITH 1 TO 2.5". GIVEN
THAT THIS SIGNAL IS NOT PARTICULARLY STRONG AND THERE IS SENSITIVITY
TO THUNDERSTORM EVOLUTION, THE THREAT OF FLASH FLOODING IS CURRENTLY
NOT HIGH ENOUGH TO WARRANT A FLOOD WATCH.
PFAHLER
LONG TERM
(WEDNESDAY THROUGH NEXT MONDAY)
ISSUED AT 243 PM CDT MON MAR 9 2026
AN UPPER-LEVEL TROUGH AND COLD FRONT WILL BE PASSING THROUGH THE CWA
WEDNESDAY MORNING INTO EARLY AFTERNOON ACCOMPANIED BY THE FINALE OF
SHOWERS AND THUNDERSTORMS. PROBABILITIES OF 500+ J/KG SBCAPE ARE
ONLY 20 TO 40 PERCENT IN GLOBAL ENSEMBLE GUIDANCE, LOWERING
CONFIDENCE IN ANY SEVERE THUNDERSTORMS BY THAT TIME, WHICH ALIGNS
WITH THE CONCERN FOR PLENTIFUL PREFRONTAL/WARM SECTOR CLOUDS AND
LINGERING OVERNIGHT PRECIPITATION. PRECIPITATION WILL GRADUALLY END
ALTOGETHER FROM WEST TO EAST DURING LATE MORNING THROUGH AFTERNOON,
BUT CLOUDS WILL LINGER LONGER AND ALLOW LOW-LEVEL CAA TO LEAD TO A
LARGELY NON-DIURNAL TEMPERATURE TREND WITH TEMPERATURES FALLING INTO
THE 40S AND 50S F BEHIND THE COLD FRONT.
UPPER-LEVEL NORTHWESTERLY FLOW WILL DOMINATE THE MID-MISSISSIPPI
RIVER VALLEY THURSDAY THROUGH SATURDAY. AN UPPER-LEVEL
TROUGH/ALBERTA CLIPPER WILL TRAVERSE THIS FLOW SOMETIME EARLY
FRIDAY, WHICH CASTS UNCERTAINTY ON HIGH TEMPERATURES ON FRIDAY AND
SATURDAY REGARDING THE TIMING OF THE ASSOCIATED COLD FRONT AND
POTENCY OF THE POST- FRONTAL AIRMASS. THEREFORE, NBM INTERQUARTILE
TEMPERATURE RANGES REACH 10 TO 15 F, BUT THERE IS GENERALLY AN
UNDERLYING WARMING TEMPERATURE TREND FROM AROUND AVERAGE ON
THURSDAY. FRONTAL PASSAGE IS ALSO FORECAST TO BE LARGELY DRY WITH
HIGHEST PROBABILITIES OF MEASURABLE RAINFALL TO THE NORTH OF THE
CWA WHERE FORCING WILL BE GREATER. GLOBAL MODEL GUIDANCE SIGNAL A
MORE POTENT UPPER-LEVEL TROUGH CROSS THE MID-MISSISSIPPI RIVER
VALLEY AROUND SUNDAY INTO MONDAY, BUT THERE IS INCREASING
VARIABILITY IN ITS AMPLITUDE, TIMING, AND TRACK. THESE FACTORS
WILL HAVE IMPLICATIONS ON THE STRUCTURE AND TRACK OF THE LOW-LEVEL
CYCLONE AND PRECIPITATION AMOUNTS, ALTHOUGH THERE IS A MUCH MORE
PRONOUNCED SIGNAL FOR PRECIPITATION THAN THE ALBERTA CLIPPER.
AROUND 20 TO 40 PERCENT OF ENSEMBLE MEMBERSHIP HAS PRECIPITATION
CHANGING TO/FALLING AS SNOW ACROSS NORTHEASTERN MO/WEST-CENTRAL IL
IN COLDER, MORE SOUTHERLY CYCLONE TRACKS.
PFAHLER
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1203 AM CDT TUE MAR 10 2026
AN AREA OF MVFR CEILINGS WILL PREVAIL ACROSS THE EASTERN OZARKS
AND SOUTHER ILLINOIS TONIGHT. THERE ARE ALSO SOME INDICATIONS THAT
ADDITIONAL STRATUS DEVELOPMENT WILL OCCUR ACROSS NORTHERN MISSOURI
IN THE VICINITY OF A FRONT, HOWEVER THESE LOWER CEILINGS MAY NOT
AFFECT OUR NORTHEAST MISSOURI AND WEST CENTRAL ILLINOIS COUNTIES.
VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR THE REMAINDER OF THE
AREA FOR THE REST OF THE NIGHT, AND LINGERING LOW CEILINGS AFTER
SUNRISE ARE EXPECTED TO RISE THROUGH THE MORNING. VFR CONDITIONS
ARE EXPECTED TO PREVAIL THEREAFTER THROUGH THE DAY INTO THE
EVENING. THERE IS A SLIGHT CHANCE FOR A THUNDERSTORM ACROSS THE
EASTERN OZARKS DURING THE AFTERNOON, AND FARTHER NORTH IN CENTRAL
AND NORTHEAST MISSOURI INTO WEST CENTRAL ILLINOIS DURING THE
EVENING. THE MAIN THREAT FOR THUNDERSTORMS NOW LOOKS TO BE
PRIMARILY AFTER 06Z WEDNESDAY.
CARNEY
CLIMATE
ISSUED AT 211 PM CST SAT MAR 7 2026
DAILY RECORD HIGH TEMPERATURES MAY BE THREATENED BOTH ON MONDAY 3/9
AND TUESDAY 3/10. BELOW ARE THE RECORDS FOR EACH DAY FROM OUR
OFFICIAL CLIMATE SITES:
MONDAY 3/9 TUESDAY 3/10
KSTL 80F (1925) 86F (1955)
KCOU 80F (1986) 82F (1955)
KUIN 75F (1986) 79F (1955)
GOSSELIN
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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