555
FXUS63 KLSX 271142
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
542 AM CST MON JAN 27 2025
KEY MESSAGES
-WARMER TEMPERATURES RETURN TODAY WITH ELEVATED FIRE DANGER BETWEEN
THE MISSOURI RIVER AND THE OZARKS INTO SOUTHWEST ILLINOIS.
-THE NEXT CHANCE OF RAIN WILL MOVE INTO THE FORECAST AREA THURSDAY
NIGHT, LINGERING THROUGH FRIDAY.
SHORT TERM
(THROUGH LATE TUESDAY AFTERNOON)
ISSUED AT 307 AM CST MON JAN 27 2025
A SURFACE HIGH IS CURRENTLY CENTERED ACROSS EASTERN KANSAS AND
THROUGH THE COURSE OF THE DAY IT WILL SINK SOUTHEAST INTO THE LOWER
MISSISSIPPI RIVER VALLEY. THE RESULTING SOUTHWESTERLY FLOW WILL
ESTABLISH ACROSS THE CWA, AND WARM AIR ADVECTION WILL PUSH
TEMPERATURES AT LEAST TEN DEGREES WARMER THAN YESTERDAY. DOWNSLOPING
OFF THE OZARKS WILL ADD A FEW DEGREES TO THE HIGH TEMPERATURES
MAINLY ACROSS SOUTHEAST MISSOURI AND SOUTHWEST ILLINOIS, BUT AS FAR
NORTH AS THE MISSOURI RIVER. ADDITIONALLY, DEWPOINTS WILL ALSO LOWER
ACROSS THIS AREA, RESULTING IN RH VALUES BELOW 30% IN THE AFTERNOON.
WITH TEMPERATURES IN THE MID 40S NORTH OF I-70 AND NEAR 50 SOUTH OF
I-70, LINGERING SNOWPACK WILL DIMINISH CONSIDERABLY TODAY EVEN IN
SHELTERED LOCATIONS.
AT THE SAME TIME, A SURFACE LOW WILL PUSH ACROSS THE GREAT LAKES
REGION, TIGHTENING THE SURFACE PRESSURE GRADIENT ACROSS THE UPPER-
MISSISSIPPI RIVER VALLEY INTO NORTHERN MISSOURI AND ILLINOIS. THIS,
COMBINED WITH EFFECTIVE MIXING WILL PUSH WIND SPEEDS INTO THE UPPER
TEENS (MPH) ACROSS THE NORTHERN FORECAST AREA WITH GUSTS INTO THE
LOW 20S. WHERE ELEVATED WINDS AND LOW RH VALUES OVERLAP AND SNOW
COVER HAS BEEN ABSENT AT LEAST 24 HOURS ELEVATED FIRE DANGER WILL
DEVELOP TODAY. THIS WILL OCCUR MAINLY ALONG AND JUST SOUTH OF THE
MISSOURI RIVER AND SOUTHWEST ILLINOIS, FOR MORE DETAILS PLEASE SEE
THE FIRE WEATHER FORECAST PRODUCT. WINDS WILL CALM OVERNIGHT AS THE
SURFACE PRESSURE GRADIENT WEAKENS AND MIXING DIMINISHES, AND THE
ELEVATED FIRE DANGER WILL LIKEWISE DIMINISH. TUESDAY WILL DAWN WITH
TEMPERATURES NEAR FREEZING. THIS RELATIVELY WARM START (COMPARED TO
THE PAST THREE WEEKS) AND ANOTHER DAY OF SOUTHWESTERLY FLOW WILL ADD
A FEW DEGREES TO TUESDAY'S HIGH IN COMPARISON TO MONDAY AND FURTHER
REDUCE THE SNOWPACK. DESPITE THE INCREASE IN TEMPERATURES, LOWER
WINDS WILL KEEP THE AREA FROM ELEVATED FIRE CONDITIONS.
DELIA
LONG TERM
(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 307 AM CST MON JAN 27 2025
BY WEDNESDAY A MID-LEVEL TROUGH WILL DIG INTO THE EASTERN CONUS,
WITH A RIDGE OVER THE WEST COAST AND CUT-OFF LOW CENTERED OVER THE
FOUR CORNERS REGION. AT THE SURFACE A LOW WILL PUSH SOUTHEAST FROM
CENTRAL CANADA INTO THE GREAT LAKES REGION OVERNIGHT TUESDAY INTO
WEDNESDAY, PUSHING A COLD FRONT THROUGH THE FORECAST AREA WEDNESDAY.
THERE WILL BE LITTLE TEMPERATURE CHANGE BEHIND THE FRONT AS THE CRUX
OF THE COLD AIR REMAINS CLOSELY TIED TO THE SURFACE LOW OVER THE
GREAT LAKES.
WARM AIR ADVECTION WILL RETURN THURSDAY AS LOW-LEVEL FLOW BECOMES
SOUTHWESTERLY ONCE AGAIN. AT THE SAME TIME THE MID-LEVEL CUT-OFF LOW
WILL DRIFT EAST AND A SURFACE LOW OVER TEXAS WILL STRENGTHEN IN
RESPONSE. THIS LOW WILL BRING THE BEST CHANCE FOR RAIN WE'VE HAD ALL
YEAR. GUIDANCE IS COMING INTO BETTER AGREEMENT THAT THE SYSTEM WILL
APPROACH THE MID-MISSISSIPPI VALLEY THURSDAY, AND ENTER THE CWA
THURSDAY NIGHT. THE RAIN WILL THEN PUSH THROUGH DURING THE DAY AND
EXIT FRIDAY NIGHT INTO SATURDAY. THE BEST FORCING FOR RAIN WILL BE
TO OUR SOUTH AND EAST, BUT CONFIDENCE IS HIGH (80%) THAT AT LEAST
MEASURABLE RAIN WILL FALL ACROSS THE ENTIRE CWA. MOISTURE RETURN
AHEAD OF THIS SYSTEM WILL BE EFFECTIVE AND PRECIPITABLE WATER
VALUES ARE FORECAST TO REACH 0.75-1.00 INCHES, THE 90TH PERCENTILE
FOR THIS TIME OF YEAR. THE BEST CHANCES OF SEEING 1.00 INCH OF
RAINFALL WILL BE CONFINED TO CLOSEST TO THE SURFACE LOW, WITH THE
PROBABILITIES OF SEEING THAT AMOUNT ONLY AROUND 50% ACROSS OUR
SOUTHERN CWA. HOWEVER 0.5" OF RAIN IS MORE REASONABLE,
PARTICULARLY ALONG AND SOUTH OF I-70 WHERE PROBABILITIES OF
EXCEEDING THIS AMOUNT ARE AROUND 70%.
GUIDANCE IS HINTING AT SOME INSTABILITY ACROSS THE FORECAST AREA ON
FRIDAY, ENOUGH TO PRODUCE A FEW CLAPS OF THUNDER AND A MORE SHOWERY
APPEARANCE TO THE PRECIPITATION. ANYWHERE THIS INSTABILITY CAN BE
UTILIZED COULD LOCALLY ENHANCE PRECIPITATION AMOUNTS. THE POTENTIAL
FOR WINTRY PRECIPITATION WITH THIS SYSTEM REMAINS LOW AS
PRECIPITATION IS EXPECTED TO HAVE EXITED THE AREA BY THE TIME COLD
AIR ADVECTION CAN PULL LOW-LEVEL TEMPERATURES BELOW FREEZING. IF
ANYTHING DEVELOPED IT WOULD BE A FEW WET SNOWFLAKES THAT QUICKLY
MELTED ON THE WARM GROUND.
AFTER A BRIEF COOL DOWN SATURDAY IN THE WAKE OF THIS SYSTEM,
TEMPERATURES WILL START TO REBOUND AS SOUTHWESTERLY LOW-LEVEL FLOW
REESTABLISHES FOR THE END OF THE WEEKEND. BEYOND THE EXIT OF THE MID-
LEVEL LOW SATURDAY, SOLUTIONS OF THE 500 MB PATTERN DIVERGE AND
THERE IS A GREAT DEAL OF UNCERTAINTY REGARDING THE SENSIBLE WEATHER
BEYOND SUNDAY.
DELIA
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 539 AM CST MON JAN 27 2025
DRY, VFR FLIGHT CONDITIONS WILL CONTINUE THROUGH THE REMAINDER OF
THE TAF PERIOD. WEST TO SOUTHWEST WINDS WILL BECOME GUSTY THIS
AFTERNOON, PARTICULARLY ACROSS KUIN, AND WILL DIMINISH WITH
SUNSET. LOW LEVEL WIND SHEAR WILL DEVELOP TONIGHT WITH WINDS FROM
THE WEST 40-50 KTS AROUND 2000 FEET, MITIGATED SOMEWHAT BY
ELEVATED WINDS AT THE SURFACE. THE LLWS WILL DEVELOP NORTHWEST OF
THE AREA AND MOVE SOUTHEAST THROUGH THE TERMINALS THIS EVENING,
CAUSING LLWS CONDITIONS FOR ONLY A FEW HOURS.
DELIA
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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