539
FXUS63 KLSX 262306
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
506 PM CST SUN JAN 26 2025
KEY MESSAGES
- WARM, DRY, AND WINDY CONDITIONS WILL EXIST BETWEEN THE MISSOURI
RIVER AND THE OZARKS, AS WELL AS SOUTHWEST ILLINOIS MONDAY,
WHICH WILL LEAD TO ELEVATED FIRE DANGER.
- DRY AND AT LEAST SEASONABLY-WARM WEATHER WILL CONTINUE THROUGH
WEDNESDAY BEFORE RAIN CHANCES INCREASE FOR THE LATTER HALF OF
THE WEEK. WINTRY PRECIPITATION CHANCES REMAIN NEAR-ZERO.
SHORT TERM
(THROUGH LATE MONDAY NIGHT)
ISSUED AT 156 PM CST SUN JAN 26 2025
COOLER AND DRIER POST-FRONTAL AIR EXISTS ACROSS THE MID-MISSISSIPPI
VALLEY WITH A SURFACE HIGH DRIFTING SOUTH AND EAST FROM THE CENTRAL
GREAT PLAINS. ALOFT, TROUGHING EXISTS ACROSS THE CONUS WITH A CUTOFF
LOW STALLED OVER CENTRAL CALIFORNIA AND A BROADER LONGWAVE OVER
EASTERN CANADA. WHILE A SCATTERED CIRRUS DECK REMAINS IN PLACE
OVERHEAD AND OBSCURED SOME SUNSHINE, THERE WAS SOME CONTINUED
EROSION OF THE REMNANT SNOWPACK ACHIEVED TODAY. YESTERDAY, COLUMBIA,
MO OFFICIALLY BROKE ITS STREAK OF HAVING AT LEAST 1 INCH OF SNOW
DEPTH YESTERDAY AFTER 20 DAYS, ENDING THE LONGEST STREAK IN ALMOST
40 YEARS. THE CIRRUS WILL CLEAR THIS EVENING WHEN A SHORTWAVE DIVING
SOUTH THROUGH THE NORTHERLY FLOW IN CENTRAL CANADA FURTHER CUTS OFF
A STREAM OF JET-LEVEL MOISTURE. THE CLEAR SKIES AND CALM WINDS WILL
SEND TEMPERATURES INTO THE TEENS AREAWIDE, WITH THE EXCEPTION OF ST.
LOUIS FALLING INTO THE LOW 20S.
WHAT'S LEFT OF THE SNOW AND ICE WILL FACE A FORMIDABLE OPPONENT
IN THE UPCOMING WARM WEATHER THAT RETURNS MONDAY. IT IS NEARLY-
CERTAIN (90% CHANCE) THAT THE REGION SEES A 10 DEGREE JUMP FROM
HIGHS TODAY WHEN THE SURFACE RIDGE SLIDES FURTHER SOUTHEAST AND A
WEAK COLD FRONT APPROACHES FROM THE NORTH, SETTING UP A GUSTY
SOUTHWEST RETURN FLOW REGIME. THE WARM AND DRY AIRMASS, COUPLED
WITH DOWNSLOPING OR BLOCKING INFLUENCES FROM THE OZARKS, WILL SEND
RH VALUES INTO THE MID-20S SOUTH OF THE MISSOURI RIVER BY THE
AFTERNOON. THERE IS A LOW (10%) CHANCE THAT LOCALLY-DRIER
CONDITIONS WOULD DEVELOP AROUND THE MOUNTAINS THEMSELVES, WHICH IS
TYPICAL IN THESE DRY SETUPS. RH VALUES INCREASE FURTHER NORTH AND
EAST (MINIMUM VALUES AS HIGH AS 35- 40%), WHERE THE OZARKS WILL
HAVE LESS INFLUENCE. WITH SUSTAINED WINDS OF AT LEAST 10MPH, THESE
CONDITIONS CAN RESULT IN ERRATIC FIRE BEHAVIOR BETWEEN THE
MISSOURI RIVER AND THE OZARKS INTO SOUTHWEST ILLINOIS WHERE THE
SNOWPACK NO LONGER EXISTS. THOSE HANDLING OPEN FLAMES SHOULD
EXERCISE CAUTION ON MONDAY (SEE FIRE WEATHER FORECAST PRODUCT FOR
MORE INFORMATION). FIRE DANGER ABATES AFTER SUNSET, BUT THE
APPROACHING COLD FRONT FALL APART AND SOUTHWEST FLOW WILL CONTINUE
OVERNIGHT. LOWS WILL RESULTANTLY BE 10-15 DEGREES WARMER THAN
TONIGHT'S.
MRB
LONG TERM
(TUESDAY THROUGH NEXT SUNDAY)
ISSUED AT 156 PM CST SUN JAN 26 2025
THE SOUTHWEST WIND WILL PERSIST INTO TUESDAY AND PROMOTE CONTINUED
WARM AIR ADVECTION. AS A RESULT, HIGH TEMPERATURES TUESDAY WILL BE
AT LEAST AS WARM AS MONDAY'S AREAWIDE. THE INFLUENCE OF THE OZARKS
WILL LIKELY LEAD TO MORE PRONOUNCED WARMING IN AND AROUND THE
MOUNTAINS, WHERE A FEW SPOTS WILL WARM TO THE UPPER 50S. NBM
INTERQUARTILE RANGES FOR TUESDAY REMAIN FAIRLY SMALL (3-4 DEGREES),
LENDING HIGHER CONFIDENCE IN THE TEMPERATURE FORECAST. WHILE MOST
GUIDANCE DRAWS DEWPOINTS HIGHER AS MORE ESTABLISHED GULF MOISTURE
ATTEMPTS TO ADVECT NORTH, THE SURFACE HIGH IS STILL FIRMLY LOCKED TO
OUR SOUTH AND WILL NOT ALLOW ROBUST HUMIDITY INCREASES. AS SUCH,
THIS FORECAST LEANS ON DRIER SOLUTIONS THAT IS MORE TYPICAL OF THESE
SETUPS. RH VALUES WILL LIKELY (80% CHANCE) FALL BELOW 40% IN THE
OZARKS AGAIN TUESDAY AS A RESULT, BUT THE LIGHTER WINDS CURRENTLY
FORECAST CURRENTLY PRECLUDE A RISK FOR ELEVATED FIRE DANGER.
ANOTHER CLIPPER DIVES INTO THE GREAT LAKES AMIDST THE CYCLONIC FLOW
ALOFT, DRAGGING A WEAK COLD FRONT INTO THE REGION LATE TUESDAY NIGHT
INTO WEDNESDAY. AS WITH THE PREVIOUS FRONT, THE COLD AIR IS LOCKED
FAR NORTH OF THE SURFACE BOUNDARY. TEMPERATURES WEDNESDAY DON'T
REALLY BUDGE COMPARED TO YESTERDAY, WITH EVEN THE COOLER END OF THE
GUIDANCE STAYING AS WARM AS TUESDAY. MEANWHILE, THE CUTOFF LOW IN
THE WESTERN CONUS GRADUALLY DRIFTS UNDER AN AMPLIFYING RIDGE AND
STALLS OVER THE DESERT SOUTHWEST. THE LOW BEGINS MARCHING DOWNSTREAM
LATE WEDNESDAY WITH A WAVE UPSTREAM IN THE GULF OF ALASKA DISLODGING
IT. THE DIFFLUENT FLOW AHEAD OF IT WILL DEVELOP A SURFACE LOW IN THE
SOUTHERN PLAINS, WHICH WILL EVENTUALLY BRING OUR FIRST
PRECIPITATION CHANCES IN QUITE SOME TIME BACK TO THE REGION. THE
POSITION AND SPEED OF THE UPPER-LEVEL LOW IS STILL QUITE VARIED
AMONG THE ENSEMBLE GUIDANCE, LEADING TO A LARGE INTERQUARTILE
RANGE FOR TEMPERATURES ON THURSDAY.
WHAT APPEARS MORE CERTAIN IS THAT PRECIPITATION CHANCES BEGIN TO
INCREASE THURSDAY AFTERNOON. THE SURFACE LOW IS VERY LIKELY TO BE
OCCLUDED BY THIS POINT, SO LONG AS THE UPPER LEVEL LOW REMAINS
CLOSED, WITH A WARM FRONT DRAPED SOMEWHERE ACROSS THE SOUTHERN
OZARKS. OVERRUNNING PRECIPITATION WILL IMPACT SOUTHERN MISSOURI AND
ILLINOIS LATE THURSDAY INTO FRIDAY, WITH THE ENTIRE REGION GETTING
SOME LIGHT RAIN BY FRIDAY MORNING. ALL PRECIPITATION IS NOW FORECAST
TO FALL AS RAIN. THERMAL PROFILES CONTINUE TO TREND WARMER, AND THE
POTENTIAL FOR ANY WINTRY PRECIPITATION IS NOW NEAR-ZERO.
DEPENDING ON HOW QUICKLY THE UPPER LEVEL LOW AND ATTENDING SURFACE
LOW EJECT, WE MAY SEE A BRIEF LULL FRIDAY MORNING, BUT IT WOULD
BE SHORT-LIVED IN THE 10-20% CHANCE THAT IT EVEN HAPPENS. WITH NO
CONVECTIVE ELEMENTS EVIDENT, WE WILL MOST LIKELY SEE A LIGHT,
PERSISTENT, UNIMPACTFUL (EXCEPT TO THE REMAINING SNOWPACK) RAIN
FRIDAY THROUGH SATURDAY.
THE UPPER LEVEL WAVE WILL EXIT THE REGION SOME TIME BETWEEN EARLY
SATURDAY AFTERNOON AND EARLY SUNDAY MORNING, AND EXACTLY WHEN WILL
DICTATE HOW WARM WE GET ON SATURDAY. SLOWER SOLUTIONS FAVOR MORE
CLOUD COVER AND RAIN, WITH COOLER TEMPERATURES. GIVEN THE LARGE
SPREAD IN SOLUTIONS, THE NBM WAS USED IN THIS FORECAST. NEAR-ZONAL
FLOW EXISTS IN THE WAKE OF THIS SYSTEM, LEAVING LOW PREDICTABILITY
FOR TEMPERATURES FOR THE EARLY PART OF NEXT WEEK. ENSEMBLE SOLUTIONS
VARY FROM WEAK RIDGING (WARMING TEMPERATURES) TO BROAD LONGWAVE
TROUGHING (COOLER, MORE PRECIPITATION CHANCES). WHILE THERE IS STILL
A LOT LEFT TO RESOLVE, CIPS EXTENDED ANALOG THREAT GUIDANCE FROM
SAINT LOUIS UNIVERSITY IS HIGHLIGHTING THE MID-MISSISSIPPI VALLEY
FOR ABOVE-NORMAL PRECIPITATION AND FAVORS THE LATTER SCENARIO
DESCRIBED ABOVE. THIS IS IN LINE WITH THE CPC 6-10 AND 8-14 DAY
OUTLOOKS, FAVORING ABOVE-NORMAL PRECIPITATION NEXT WEEK WITH A
COOLDOWN LOOMING NEXT WEEK.
MRB
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 504 PM CST SUN JAN 26 2025
VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE 00Z TAF PERIOD.
LINGERING CIRRUS IS LIKELY TO DIMINISH OVERNIGHT, AN MOSTLY CLEAR
SKIES ARE EXPECTED THE REMAINDER OF THE PERIOD. BREEZY SOUTHWEST
WINDS WILL DEVELOP DURING THE AFTERNOON TOMORROW AND PERSIST
THROUGH THE END OF THE TAF PERIOD.
-BRC
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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