647
FXUS63 KLSX 170711
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
211 AM CDT TUE MAR 17 2026
KEY MESSAGES
- TODAY'S TEMPERATURES WILL BE SLIGHTLY MILDER THAN MONDAY, BUT REMAIN
AROUND 20 DEGREES BELOW NORMAL WITH HIGHS IN THE 30S TO LOW-
40S.
- LIGHT SNOW IS EXPECTED OVER SECTIONS OF NORTHEAST MISSOURI AND WEST-
CENTRAL ILLINOIS TONIGHT. ACCUMULATIONS REMAIN UNDER AN INCH.
- TEMPERATURES WARM SIGNIFICANTLY FROM WEDNESDAY THROUGH THE END
OF THE WEEK WITH HIGHS EXPECTED TO BE WELL ABOVE NORMAL.
SHORT TERM
(THROUGH LATE WEDNESDAY AFTERNOON)
ISSUED AT 205 AM CDT TUE MAR 17 2026
SKIES HAVE CLEARED OUT OVER MUCH OF THE AREA WITH THE ONLY SEMBLANCE
JUST NOW EXITING THE EASTERN FRINGES OF THE CWA. SURFACE
OBSERVATIONS SHOW GUSTS CONTINUING TO SUBSIDE WITH SUSTAINED WINDS
DROPPING BELOW 10 MPH OVER CENTRAL MISSOURI. THIS EASTWARD WILL
CONTINUE THROUGH EARLY MORNING, WHICH MAY ALLOW LOW TEMPERATURES TO
COOL A BIT MORE EFFICIENTLY THAT PREVIOUSLY THOUGHT. MORNINGS LOWS
COULD BE TRIMMED JUST A HAIR, BUT NEGLIGIBLE IN SENSIBLE TERMS. MOST
LOCATIONS WAKE UP TO THE TEENS WITH A FEW SINGLE DIGIT READINGS IN
NORTHEAST MISSOURI.
SUBTLE WARMING IS EXPECTED TODAY AFTER SUCH A COLD START. CALLING IT
A WARM-UP MAY BE MORE INSULTING THAT TRUTHFUL WITH HIGHS LARGELY IN
THE 30S TO NEAR 40 DEGREES. WE'RE AHEAD OF A WEAK CLIPPER SYSTEM
THAT WILL BRING ADDITIONAL CLOUDS TO THE REGION THROUGH THE
AFTERNOON. HOW QUICKLY THIS OCCURS COULD STYMIE DIURNAL TRENDS,
MAINLY OVER CENTRAL AND NORTHEAST MISSOURI. THE FAVORED NORTHERN
TRACK, QUICK PACE, AND LACK OF MOISTURE WILL KEEP WINTER HAZARDS AT
BAY. AN ADDED BENEFIT IS THAT PRECIPITATION CHANCES LARGELY LIE
BETWEEN SUNSET TONIGHT AND SUNRISE WEDNESDAY MORNING.
THE CLIPPER RIDES ALONG A WING OF STRONG WARM AIR ADVECTION WITH
SURFACE TEMPERATURES AT OR ABOVE FREEZING FROM KIRKSVILLE TO ST.
LOUIS THROUGH MT. VERNON (IL) THROUGH TONIGHT. THE WARM NOSE
CONTINUES TO CUT INTO NORTHEAST FRINGES OF THE CWA BETWEEN 09Z-11Z
PRIOR TO SUNRISE, RESULTING IN SLOWLY RISING TEMPERATURES BETWEEN
06Z-12Z TONIGHT INTO EARLY WEDNESDAY MORNING. EVEN THE COLDEST
LOCATIONS ACROSS THE NORTHEAST FRINGES OF THE CWA ONLY BOTTOM OUT IN
THE LOW-30S. HREF SPREADS HAVE BEEN CONSISTENTLY SHOWING AROUND
0.05" OF QPF FROM KUIN THROUGH K3LF. THERE'S ALSO REASSURANCE IN THE
LPMM DATA THAT SHOWS AN INCH OF ACCUMULATION IN THESE AREAS.
REALISTICALLY, MAYBE AN INCHES IS ACHIEVED NORTH OF KUIN WITH LESS
THAN AN INCH ELSEWHERE. MOISTURE DEPTH DECREASES SOUTHWEST FROM
THERE WITH A MORE NOTABLE DRY LAYER IN THE SURFACE TO MID-LEVEL
LAYER. WHAT MOISTURE IS AVAILABLE IS LIKELY TO BE VERY LIGHT AND IN
LIQUID FORM. NO HAZARDS ARE EXPECTED AT THIS TIME.
THERE IS HIGH CONFIDENCE IN A SIGNIFICANT WARM-UP STARTING WEDNESDAY
AS A RIDGE AXIS CROSSES THE REGION, SHIFTING WINDS OUT OF THE
SOUTHWEST. H8 TEMPERATURES CLIMB ABOUT 10C WITH HIGHS LARGELY IN THE
60S.
MAPLES
LONG TERM
(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 205 AM CDT TUE MAR 17 2026
THE LATER HALF OF THE WEEK FEATURES MUCH WARMER TEMPERATURES THAT
WILL COMPARE CLOSER TO THE FIRST HALF OF MAY. NBM IQR PROVIDES HIGH
CONFIDENCE IN THE WARM-UP WITH JUST A FEW DEGREES OF SEPARATION
BETWEEN THE 25TH/75TH PERCENTILES. GLOBAL DETERMINISTIC GUIDANCE
SHOWS MID-LEVEL TEMPERATURES INCHING UPWARD THROUGH THIS STRETCH,
STARTING OUT AT 10-15C THURSDAY AND NEAR 20C SATURDAY. THIS WILL
BRING TEMPERATURES INTO THE 60S/70S THURSDAY AND WELL INTO THE 70S
FRIDAY. SATURDAY IS A TOUCH WARMER THAN FRIDAY, WHICH INCLUDES LOW-
80S OVER SECTIONS OF CENTRAL AND SOUTHEAST MISSOURI. PROMINENT FLOW
AT THE SURFACE IS MORE WESTERLY THAN SOUTHWESTERLY AND THEREFORE
DOES NOT INDICATE MUCH POTENTIAL FOR OVER-PERFORMANCE. NBM OUTPUT
LOOKS REASONABLE WITH IQR REMAINING TIGHTLY CLUSTERED THROUGH
SATURDAY.
SUNDAY REMAINS THE BIGGEST QUESTION WITH RELATION TO A COLD FRONT
THAT BRINGS COOLER AIR TO THE REGION. THIS MORNING'S DETERMINISTIC
ECMWF/GFS ARE IN FAIR AGREEMENT WITH THE SURFACE FRONT ARRIVING IN
THE EARLY MORNING OVER NORTHERN MISSOURI/WEST-CENTRAL ILLINOIS, MID-
MORNING ALONG I-70, AND BY 18Z OVER THE SOUTHERN STRETCH OF THE CWA.
NBM SPREADS AROUND 30 DEGREES PERSIST, WHICH IS LARGELY PLAYING OFF
THE WARMER ECMWF SOLUTIONS FROM PRIOR RUNS. THIS SPREAD ALSO SHOWS
UP IN THE HREF ENSEMBLES, BUT I SUSPECT THIS WILL BEGIN TO TIGHTEN
OVER THE NEXT COUPLE OF RUN AS WE DRAW CLOSER TO THE WEEKEND. THAT
BEING SAID, MOST AREAS ALONG AND NORTH OF I-70 LIKELY REACH THEIR
HIGH TEMPERATURES IN THE EARLY PART OF THE DAY, THEN FOLLOW A NON-
DIURNAL TREND THROUGH THE AFTERNOON. 70S ARE MOST FAVORED ACROSS
SOUTHEAST MISSOURI AND SOUTHWEST ILLINOIS AS 20-25C H8 AIR IS
COMPRESSED ALONG AND JUST AHEAD OF THE BOUNDARY WITH SOME TIME FOR
NORMAL DIURNAL PROCESSES TO HAVE GREATER INFLUENCE ON TEMPERATURES.
CONSIDERING THE SURFACE RIDGE REMAINS TO OUR SOUTHWEST AHEAD OF THE
FRONT, MOISTURE RETURN IS LACKING UNTIL THE FRONT APPROACHES THE
MISSOURI/ARKANSAS BORDER. THUS, A DRY FROPA IS FAVORED.
A STRONG SURFACE RIDGE BUILDS EASTWARD THROUGH THE NORTH-CENTRAL
U.S. EARLY NEXT WEEK. NBM SPREADS AREN'T TERRIBLY LARGE (~10
DEGREES) WITH THE MOST NOTABLE CHARACTERISTIC BEING AN INITIAL DROP
IN TEMPERATURE MONDAY WITH MODEST MODERATION THEREAFTER.
MAPLES
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1232 AM CDT TUE MAR 17 2026
SKIES HAVE CLEARED AND WINDS CONTINUE TO DIE OFF AT ALL TERMINALS
EARLY THIS MORNING. A QUICK-MOVING CLIPPER SYSTEM PASSES OVER THE
REGION TONIGHT WITH LIGHT RAIN/SNOW POSSIBLE, MAINLY AROUND KUIN.
SURFACE TO MID-LEVELS BECOME INCREASINGLY DRY SOUTHWEST OF KUIN,
INCLUDING CENTRAL MISSOURI/METRO TERMINALS. THE LACK OF MOISTURE
AND QUICK PACE OF THIS SYSTEM MAY NOT PROVIDE MUCH OPPORTUNITY TO
OVERCOME THE DRY LAYER. THEREFORE, THE ONLY MENTION OF -SN IS AT
KUIN. EVEN IN THIS INSTANCE CLOUD BASES REMAIN VFR WITH MVFR
SKIMMING NORTHEAST OF KUIN THROUGH CENTRAL ILLINOIS.
MAPLES
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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