893
FXUS63 KLSX 131906
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
206 PM CDT FRI MAR 13 2026
KEY MESSAGES
- MILD WEATHER CONTINUES FOR A FEW DAYS, BUT A STRONG FRONT ON
SUNDAY BRINGS A SHARP TEMPERATURE PLUNGE BACK TO WINTER-LIKE
COLD.
- SUNDAY'S FRONT BRINGS THE POTENTIAL FOR SEVERE THUNDERSTORMS
AHEAD OF IT AND SNOW BEHIND IT.
SHORT TERM
(THROUGH LATE SATURDAY NIGHT)
ISSUED AT 205 PM CDT FRI MAR 13 2026
A DEEP LOW PRESSURE SYSTEM IS OCCLUDING OVER THE GREAT LAKES THIS
AFTERNOON WHILE SURFACE HIGH PRESSURE IS NOSING IN AROUND IT TO THE
WEST AND SOUTH. OUR REGION EXPERIENCED A SUBTLE FRONTAL PASSAGE
TODAY WITH WINDS SHIFTING TO THE NORTHWEST. THESE WINDS DIE DOWN
THIS EVENING AND TURN SOUTHEASTERLY BY MORNING AS THE SURFACE HIGH
SLIDES BY TO OUR NORTH. TODAY'S FRONT THEN BEGINS TO LIFT BACK NORTH
AS A WARM FRONT ON SATURDAY, SO OUR BRIEF ENTRY INTO THE COOL SECTOR
DOESN'T LAST LONG. TEMPERATURES ON SATURDAY WILL VARY STRONGLY FROM
NORTHEAST TO SOUTHWEST AS NORTHEASTERN AREAS STAY IN THE COOL SECTOR
MOST OF THE DAY WITH CLOUDS AND COOLER TEMPERATURES (IN THE 40S AND
50S). FURTHER SOUTH AND WEST, WINDS SHIFT TO THE SOUTH AND THE SUN
COMES OUT, WARMING TEMPERATURES INTO THE 60S TO NEAR 70.
KIMBLE
LONG TERM
(SUNDAY THROUGH NEXT FRIDAY)
ISSUED AT 205 PM CDT FRI MAR 13 2026
LOOKING FURTHER UPSTREAM A TROUGH IS JUST BEGINNING TO ENTER THE
PACIFIC NORTHWEST AND AS IT EMERGES OUT OF THE NORTHERN ROCKIES
SATURDAY NIGHT IT IS PROJECTED TO DIG A MUCH SHARPER TROUGH ACROSS
THE PLAINS. A SURFACE LOW RAPIDLY STRENGTHENS AND TRACKS NEAR THE
MISSOURI/IOWA BORDER SUNDAY AFTERNOON BEFORE PULLING NORTHEAST TO
THE GREAT LAKES AND DRAGGING A STRONG COLD FRONT SOUTHEAST BEHIND
IT. AHEAD OF THE LOW IN THE WARM SECTOR, LOW LEVEL MOISTURE
INCREASES. DEWPOINTS RISE INTO THE 50S AND THE TEMPERATURE WELL INTO
THE 60S (WITH MORE SUN, INTO THE 70S). MEANWHILE, THE DEEPENING LOW
INCREASES THE WIND FIELD ACROSS THE REGION, BOTH AT THE SURFACE AND
ALOFT. THIS LEADS TO STRONG WIND SHEAR ACROSS THE WARM SECTOR WITH
SOUTHWESTERLY 850 WINDS UP AROUND 50 KT. THAT'S A PRETTY FAVORABLE
SHEAR ENVIRONMENT FOR SEVERE THUNDERSTORMS.
THE LIMITING FACTOR AS IS USUALLY THE CASE THIS TIME OF YEAR IS
INSTABILITY. BETTER MOISTURE RETURN REMAINS LIMITED FURTHER TO THE
SOUTH. BY COMPARISON, DURING THE SEVERE WEATHER EVENT EARLIER THIS
WEEK WE SAW DEWPOINTS WELL INTO THE MID 60S GENERATING A LOT MORE
INSTABILITY FOR THUNDERSTORMS TO FEED ON. WE'RE DEFINITELY NOT
LOOKING AT THAT LEVEL OF INSTABILITY LOCALLY THIS TIME, BUT LOW
RESOLUTION GUIDANCE DOES SHOW UP TO ABOUT A 20 PERCENT CHANCE OF
CAPE REACHING 500 OR HIGHER AHEAD OF THE FRONT. WITH THAT KIND OF
SHEAR, IT DOESN'T TAKE MUCH INSTABILITY FOR SEVERE STORMS TO OCCUR,
BUT THE HIGHER END SEVERE POTENTIAL WILL BE MORE LIMITED TO AREAS
WITH GREATER INSTABILITY TO OUR SOUTHEAST. FORECAST ATMOSPHERIC
PROFILES SHOW A STRONG CAP ACROSS THE WARM SECTOR ON SUNDAY, SO IT
WILL TAKE STRONG CONVERGENCE ALONG THE COLD FRONT OR A WEAKENING OF
THE CAP FOR STORMS TO INITIATE. IT WILL LIKELY TAKE UNTIL THE
AFTERNOON FOR INITIATION TO BEGIN ALONG THE COLD FRONT AS IT'S
MOVING INTO CENTRAL AND NORTHERN MISSOURI. WHILE SHEAR IS STRONG IN
THE WARM SECTOR, IT'S ALSO ORIENTED ALMOST PARALLEL TO THE COLD
FRONT ITSELF, SUGGESTING THAT STORMS THAT FORM WILL QUICKLY MERGE
INTO A LINE. THIS PUTS OUR SEVERE WEATHER FOCUS ON DAMAGING WINDS
AND PERHAPS A TORNADO OR TWO DEPENDING ON WHERE BENDS AND KINKS IN
THE LINE DEVELOP. WHILE THE GREATEST THREAT REMAINS TO OUR SOUTHEAST
WHERE INSTABILITY IS STRONGER, THE LATEST TRENDS IN GUIDANCE HAVE
SHIFTED TOWARD A LITTLE FURTHER WEST WITH INITIATION, SO THE OVERALL
MINIMAL THREAT LEVEL HAS SHIFTED A BIT WESTWARD.
THE COLD FRONT PUSHES QUICKLY EAST ACROSS THE AREA SUNDAY EVENING,
ARRIVING IN CENTRAL MISSOURI IN THE MID AFTERNOON AND PROGRESSING
EAST THROUGH THE EVENING. THIS IS A VERY POTENT FRONT WITH VERY COLD
AIR BEING PULLED IN BEHIND IT. SOME HIGHER RESOLUTION GUIDANCE SHOWS
A SHARP 20 DEGREE TEMPERATURE DROP WITHIN JUST A FEW MINUTES OF THE
FRONTAL PASSAGE, AND NEARLY ALL GUIDANCE AGREES THAT WITHIN 6 TO 12
HOURS THE TEMPERATURE WILL HAVE DROPPED AS MUCH AS 50 DEGREES, FROM
THE MID 60S TO THE MID TEENS IN SPOTS. WHILE SOME OF THE RAIN FORCED
ALONG THE FRONT MAY EXTEND BACK BEHIND IT SOMEWHAT, IT'S LIKELY THAT
THIS ROUND OF PRECIPITATION ENDS AS RAIN AS THE COLDER/DRIER AIR
ARRIVES BEHIND THE FRONT. HOWEVER, THE RAPIDLY DEEPENING LOW WILL
DEVELOP AN AREA OF WRAP AROUND PRECIPITATION. CONFIDENCE IS HIGH
THAT THIS AREA OF PRECIPITATION WILL FALL AS SNOW WITH RATES OF 0.5
TO 1 INCH PER HOUR POSSIBLE. WHERE THIS DEVELOPS, WHERE IT TRACKS,
AND HOW INTENSE IT WILL BE ARE STILL UNCERTAIN. CONFIDENCE IS
GREATEST TO THE NORTH ACROSS IOWA, WITH ADJACENT AREAS OF NORTHEAST
MISSOURI ALSO LIKELY IMPACTED. HOWEVER, THIS BAND COULD EXTEND AS
FAR SOUTHWEST AS CENTRAL MISSOURI. AS THE LOW LIFTS OUT TO THE
NORTHEAST, THE BAND OF SNOW LIFTS OUT WITH IT. HOWEVER, THERE'S SOME
POTENTIAL THAT IT PIVOTS EASTWARD AS IT PULLS AWAY, BRINGING AT
LEAST A DUSTING OF SNOW TO MOST OF OUR FORECAST AREA. AREAS OF
NORTHEAST MISSOURI ARE LIKELY TO BE IN THE BAND OF SNOW LONGEST, AND
THUS HAVE THE HIGHEST FORECAST ACCUMULATIONS AT THIS POINT. WITH THE
RECENT WARMTH, IT MAY TAKE SOME TIME FOR ROADS TO COOL TO THE POINT
OF ACCUMULATION, BUT STRONG WINDS ARE EXPECTED TO ASSIST IN COOLING
SURFACES QUICKLY BEHIND THE FRONT.
SPEAKING OF WINDS, THIS SYSTEM HAS A LOT OF THAT. EVEN AHEAD OF THE
LOW IN THE WARM SECTOR, GUSTS TO 30 TO 35 MPH ARE EXPECTED. BUT
BEHIND THE COLD FRONT IN THE COLD ADVECTION WE'LL SEE THE GREATEST
POTENTIAL FOR STRONG WINDS. NBM FORECAST WIND GUSTS WERE A LITTLE
LOW COMPARED TO EXPECTATIONS FOR THIS TYPE OF SCENARIO, SO WE
COORDINATED WITH MOST NEIGHBORING OFFICES TO INCREASE THESE IN THE
FORECAST. ONE FIELD THAT HAS PROVED VERY USEFUL IN RECENT SIMILAR
COLD FRONTAL EVENTS HAS BEEN THE NBM 24 HOUR MAX WIND GUST
POTENTIAL. THIS SHOWS ABOUT A 60 TO 90 PERCENT PROBABILITY OF WIND
GUSTS OF 45 MPH OR HIGHER. ON THE MORE EXTREME END, IT EVEN SHOWS UP
TO A 30 PERCENT CHANCE OF GUSTS TO 60 MPH. THIS FITS WELL WITH AN
ANALYSIS OF THE LOW LEVEL ATMOSPHERIC PROFILE SHOWING STRONG WINDS
AT THE TOP OF THE MIXED LAYER IN STRONG COLD ADVECTION. AMONG THE
LOW RESOLUTION ENSEMBLE GUIDANCE, UP TO 30 PERCENT OF ENSEMBLE
MEMBERS SHOW 925MB WINDS OF 50KT OR HIGHER, JUST ABOUT ALL OF WHICH
WOULD BE ABLE TO MIX TO THE SURFACE IN STRONG COLD ADVECTION. SO AT
THIS POINT WE HAVE RELATIVELY HIGH CONFIDENCE IN A PERIOD OF
ADVISORY LEVEL WIND GUSTS (45MPH+) BEHIND THE FRONT SUNDAY NIGHT,
WITH AT LEAST SOME LOW POTENTIAL FOR HIGH WIND WARNING CRITERIA
GUSTS (58MPH+).
THE COMBINATION OF THE COLD AND THE WIND WILL MAKE IT FEEL EVEN
COLDER. WIND CHILL VALUES POTENTIALLY DROP BELOW ZERO BY MONDAY
MORNING. WHILE WINDS DECREASE DURING THE MORNING HOURS ON MONDAY,
THE TEMPERATURE DOESN'T WARM UP ALL THAT MUCH. NBM SHOWS A 50 TO 90
PERCENT PROBABILITY OF HIGH TEMPERATURES REMAINING BELOW FREEZING ON
MONDAY DESPITE DECREASING CLOUD COVER. THE COLDEST TEMPERATURES ARE
LIKELY MONDAY NIGHT WHEN THE CENTER OF THE SURFACE HIGH CROSSES THE
REGION BRINGING A PERIOD OF LIGHT OR CALM WINDS. DEWPOINTS IN THE
MID SINGLE DIGITS SUGGEST THAT WITH A CLEAR SKY AND SEVERAL HOURS OF
CALM WINDS, SHELTERED VALLEYS MAY DROP BELOW 10 DEGREES. WE HAVEN'T
SEEN THIS KIND OF COLD IN 3 WEEKS OR MORE, AND AFTER OUR RECENT
WARMTH IT WILL BE QUITE A CONTRAST.
THE WARM UP BEGINS TUESDAY AS HIGH PRESSURE SHIFTS EAST AND RIDGING
ALOFT GRADUALLY EXPANDS OUT OF THE WESTERN US THROUGH THE WEEK. IN
FACT, WE WARM BACK INTO THE 60S AS EARLY AS WEDNESDAY AND REACH THE
70S AS EARLY AS THURSDAY. APART FROM A WEAK CLIPPER STYLE SYSTEM OR
TWO, THE REST OF THE WEEK SHOULD BE MAINLY DRY.
KIMBLE
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1214 PM CDT FRI MAR 13 2026
VFR CONDITIONS CONTINUE THROUGH SATURDAY. GUSTY NORTHWEST WINDS
THIS EVENING DIMINISH AND GO LIGHT AND VARIABLE OVERNIGHT TONIGHT.
THEN SOUTHEAST WINDS PICK UP ON SATURDAY. ONLY A FEW PASSING HIGH
CLOUDS ARE EXPECTED THROUGH THE PERIOD.
KIMBLE
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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