014
FXUS63 KLSX 250817
AFDLSX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
217 AM CST SAT JAN 25 2025
KEY MESSAGES
- AFTER A MILD DAY TODAY, WE'LL SEE A BRIEF COOL DOWN SUNDAY
BEFORE A REBOUND BACK TO MILD TEMPERATURES FOR THE FIRST HALF
OF NEXT WEEK.
- DRY WEATHER LASTS THROUGH AT LEAST THE FIRST HALF OF NEXT WEEK,
WITH PRECIPITATION CHANCES INCREASING TOWARD THE END OF NEXT
WEEK.
SHORT TERM
(THROUGH LATE SUNDAY AFTERNOON)
ISSUED AT 217 AM CST SAT JAN 25 2025
SURFACE HIGH PRESSURE IS OFF TO OUR EAST THIS MORNING, CENTERED
AROUND THE SOUTHERN APPALACHIAN MOUNTAINS. THIS HAS BEGUN A SOUTH TO
SOUTHWEST FLOW ACROSS OUR REGION LEADING TO A CONTINUED WARM UP
TODAY. TEMPERATURES THIS AFTERNOON WILL BE SOME 10 TO 15 DEGREES
WARMER THAN YESTERDAY. TO OUR NORTH A TROUGH PUSHING EAST ACROSS THE
GREAT LAKES SENDS A COLD FRONT SOUTHEAST TOWARD OUR AREA. THE COLDER
AIR ASSOCIATED WITH THIS FRONT DOESN'T REALLY ARRIVE IN OUR FORECAST
AREA UNTIL LATE IN THE DAY SATURDAY, SO WE EXPECT ALL AREAS WILL GET
IN ON THE WARM UP TODAY. NORTHERN AREAS WON'T BE AS WARM DUE TO
CLOUD COVER AND SOME COOLER TEMPERATURES ALOFT UP THERE, BUT EVEN
THERE WE'LL BE WARMING WELL ABOVE FREEZING. TO THE SOUTH, THE
TEMPERATURE WILL MAKE A RUN AT 50 DEGREES.
COOLER AIR POURS IN BEHIND THE FRONT TONIGHT INTO SUNDAY, BUT WE'RE
NOT TALKING COLD TO THE EXTREME LEVEL THAT WE'VE SEEN RECENTLY. THE
COLD TONIGHT WILL BE DRIVEN BY COLD ADVECTION, WITH COLDEST
TEMPERATURES IN THE NORTH. ALL AREAS FALL BACK BELOW FREEZING BY
SUNDAY MORNING. SURFACE HIGH PRESSURE ASSOCIATED WITH THIS COOL AIR
MASS MOVES SOUTH THROUGH THE REGION ON SUNDAY. NORTHERN AREAS MAY
NOT RISE ABOVE FREEZING, BUT SOUTHERN AREAS REACH THE MID 30S TO
POSSIBLY 40 DEGREES. THE HIGH CONTINUES SETTLING SOUTH SUNDAY NIGHT.
DEPENDING ON CLOUD COVER THIS COULD BE A PRETTY GOOD RADIATIONAL
COOLING SCENARIO WITH THE COLDEST TEMPERATURES OF THIS AIR MASS.
DEWPOINTS IN THE TEENS SUGGEST THAT'S ABOUT WHAT THE COLDEST
TEMPERATURES WILL BE IF WE DO GET THOSE CLEAR, CALM CONDITIONS.
KIMBLE
LONG TERM
(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 217 AM CST SAT JAN 25 2025
FOR NEXT WEEK THE UPPER AIR PATTERN WILL PRIMARILY FEATURE NORTHWEST
FLOW THROUGH THE CENTER OF THE COUNTRY DOWNSTREAM FROM A HIGH
AMPLITUDE RIDGE OVER BRITISH COLUMBIA. A SERIES OF TROUGHS ROTATE
AROUND A BROADER UPPER TROUGH OVER HUDSON BAY AND QUEBEC, EVENTUALLY
BUILDING A BROADER TROUGH SOUTHWARD ENCOMPASSING MORE OF THE EASTERN
US THROUGH THE END OF THE WEEK. TO THE WEST AN UPPER LOW IS DIVING
SOUTHWARD ALONG THE CALIFORNIA COAST, BECOMING CUT OFF FROM THE FLOW
AND LINGERING OVER THE SOUTHWEST US FOR MUCH OF THE WEEK. WHEN THIS
LOW FINALLY MOVES EASTWARD IT WILL BRING OUR NEXT SIGNIFICANT CHANCE
OF PRECIPITATION LATE IN THE WEEK.
AFTER SUNDAY'S COOL DOWN, MONDAY WILL SEE TEMPERATURES REBOUND IN A
BROAD WSW FLOW TO THE NORTH OF THE SURFACE HIGH SINKING TOWARD THE
GULF COAST. TEMPERATURES WARM SOME 10 DEGREES ON MONDAY, INTO THE
40S, AND THEN ANOTHER 5 DEGREES OR SO ON TUESDAY, INTO THE UPPER 40S
TO LOW 50S. THERE'S RELATIVELY HIGH CONFIDENCE IN THESE TEMPERATURES
AS SEEN BY A RELATIVELY SMALL (3 TO 5 DEGREE) INTERQUARTILE RANGE IN
THE NBM. DRY CONDITIONS PERSIST WITH GULF MOISTURE BEING BLOCKED
WELL TO THE SOUTH.
BY THE MIDDLE OF THE WEEK, THE SERIES OF TROUGHS ROTATING THROUGH
THE GREAT LAKES BEGIN TO SEND A SERIES OF COLD FRONTS SOUTHWARD. THE
FIRST TO REACH OUR AREA IS LIKELY ON WEDNESDAY WITH THE POTENTIAL
FOR A FEW MORE AFTER THAT. THERE'S A LOT GREATER UNCERTAINTY IN THE
TEMPERATURE FORECAST AS WE HEAD LATER INTO THE WEEK DUE TO THE
POTENTIAL CHANGES IN AIR MASSES. WHILE IT LOOKS LIKE THE CORE OF THE
COLD WILL PUSH TO OUR EAST WITH THE BROADER TROUGH, JUST HOW MUCH
SLIDES INTO OUR AREA, AND WHEN, IS MORE UNCERTAIN. THIS UNCERTAINTY
IS SHOWN IN THE RELATIVELY LARGER (8 TO 11 DEGREES) NBM
INTERQUARTILE RANGES LATER IN THE WEEK.
ENSEMBLE DATA IS STARTING TO COME INTO BETTER AGREEMENT ON THE
TIMING OF WHEN THE SOUTHWEST UPPER LOW PULLS OUT INTO THE PLAINS.
JUST 24 HOURS AGO, THE TIME WINDOW WE WERE LOOKING AT FOR THIS
SYSTEM WAS RATHER BROAD, FROM THURSDAY TO SATURDAY. BUT LATEST
GUIDANCE HAS NARROWED THIS WINDOW CONSIDERABLY, FOCUSING ON THE
FRIDAY NIGHT TIME PERIOD FOR PRECIPITATION IN OUR AREA. THIS GREATER
CONFIDENCE IN TIMING IS REFLECTED IN HIGHER POP VALUES IN OUR
FORECAST, WITH OUR POP RISING TO AS HIGH AS 60 PERCENT FRIDAY NIGHT.
OUR CONFIDENCE IN GETTING PRECIPITATION OUT OF THIS SYSTEM CONTINUES
TO BE EVEN HIGHER THAN THAT (UP TO 80 PERCENT OF ENSEMBLE GUIDANCE
PRODUCES MEASURABLE PRECIPITATION IN THE 24 HOUR PERIOD ENDING ON
SATURDAY AFTERNOON), BUT THE LINGERING TIMING UNCERTAINTY CONTINUES
TO SPREAD THESE CHANCES OUT A BIT MORE BROADLY THROUGH THE TAIL END
OF OUR FORECAST, WITH LOW PRECIPITATION CHANCES BEGINNING AS EARLY
AS THURSDAY NIGHT. THIS WILL LIKELY BE REFINED FURTHER AS THE
GREATER TIMING CONSENSUS EMERGING IN THE GUIDANCE BECOMES MORE
REFLECTED IN THE NBM.
THE GENERAL CONSENSUS IS THAT THE UPPER LOW TRACKS NORTHEAST THROUGH
THE CENTRAL PLAINS WITH OUR AREA BEING SHOVED INTO THE WARM SECTOR
OF THE BROADER CYCLONE AS IT MOVES THROUGH. THIS SUGGESTS WARMING
TEMPERATURES AND PRIMARILY A RAIN FORECAST, BUT WINTRY WEATHER IS
POSSIBLE ESPECIALLY AT THE ONSET OF PRECIPITATION. WITH THE WARM AIR
BEING ADVECTED INTO AND OVER A COLDER AIR MASS, INVERTED TEMPERATURE
PROFILES BECOME MORE LIKELY AND PRECIPITATION COULD BEGIN AS SNOW,
SLEET, OR FREEZING RAIN BEFORE THE SURFACE TEMPERATURE WARMS ABOVE
FREEZING. UNFORTUNATELY DUE TO THE LARGER UNCERTAINTY ON THE
TEMPERATURE FORECAST LATE IN THE WEEK, COMBINED WITH THE LINGERING
TIMING UNCERTAINTY OF THIS WAVE, IT'S HARD TO HAVE MUCH CONFIDENCE
IN WHAT, WHEN, AND WHERE ANY WINTRY PRECIPITATION WILL BE.
OVERALL PRECIPITATION AMOUNTS LOOK LIGHT TO MODERATE. PERSISTENT
EASTERLY FLOW OVER THE GULF NEXT WEEK WILL LEAD TO A BUILD UP OF
MOISTURE OVER TEXAS IN ADVANCE OF THE TROUGH'S ARRIVAL. SO THERE
WILL BE A SIGNIFICANT PULL OF MOISTURE NORTHEASTWARD ALONG WITH IT.
BUT IT DOES MOVE THROUGH RELATIVELY QUICKLY WHICH LIMITS TOTAL
PRECIPITATION AMOUNTS. ONLY UP TO ABOUT 20 PERCENT OF ENSEMBLE
GUIDANCE PRODUCES 0.50 INCHES OF PRECIPITATION OR HIGHER.
KIMBLE
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1024 PM CST FRI JAN 24 2025
TONIGHT'S LLJ WILL CONTINUE TO SHIFT EAST, MOVING LLWS IMPACTS OUT
OF NORTHEAST MO AND WEST-CENTRAL IL, AND PUTTING MORE FOCUS ON
MID-MO THROUGH SOUTH-CENTRAL IL UNTIL ABOUT SUNRISE. A DRY COLD
FRONT WILL SLOWLY PUSH THROUGH THE FORECAST AREA SATURDAY WITH
WINDS VEERING TO THE NORTHWEST BEHIND IT.
JAJA
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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