818
FXUS63 KLSX 200409
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
1009 PM CST SUN JAN 19 2025
KEY MESSAGES
- VERY COLD CONDITIONS WILL PERSIST THROUGH WEDNESDAY MORNING.
THE COLDEST MORNING IS STILL EXPECTED TO BE TUESDAY MORNING,
WITH WIND CHILLS FALLING TO BETWEEN 0 AND -15 DEGREES C, AND
POTENTIALLY A FEW DEGREES LOWER IN A FEW LOCATIONS.
- TEMPERATURES WILL MODERATE QUICKLY WEDNESDAY DURING THE DAY, AND
MORE SEASONABLE TEMPERATURES ARE EXPECTED THROUGH THE END OF THE
WEEK.
SHORT TERM
(THROUGH LATE MONDAY NIGHT)
ISSUED AT 231 PM CST SUN JAN 19 2025
WHILE CERTAINLY NOT NEWS TO ANYONE WHO VENTURED OUTSIDE TODAY, IT IS
DOWNRIGHT COLD ACROSS THE AREA AS A REINFORCING SURGE OF ARCTIC AIR
ARRIVED OVERNIGHT. TEMPERATURES OVERNIGHT WERE SOMEWHAT VARIABLE
ACROSS THE AREA BUT STILL MUCH COLDER THAN THE PREVIOUS NIGHT, WITH
VALUES RANGING FROM THE LOW TEENS ACROSS SOUTHEAST MO / SOUTHWEST IL
ON THE UPPER END, TO THE LOW SINGLE DIGITS ACROSS NORTHEAST MO /
WEST- CENTRAL IL. GUSTY WINDS ALSO BROUGHT WIND CHILLS TO WITHIN A
DEGREE OR TWO OF COLD ADVISORY HEADLINES, WITH VALUES RANGING
FROM THE LOW SINGLE DIGITS ON THE UPPER END, ALL THE WAY DOWN TO
NEAR -15 DEGREES ON THE LOWER END. THESE VALUES HAVE INCREASED
SLIGHTLY EARLY AFTERNOON, BUT PERSISTENT GUSTY WINDS AND COLD AIR
ADVECTION IS WORKING AGAINST THE SUN AND THIS IMPROVEMENT HAS BEEN
MARGINAL AT BEST. STILL, IT'S JUST ENOUGH TO KEEP COLD HEADLINES
AT BAY UNTIL TONIGHT, WHEN ACTUAL TEMPERATURES ARE LIKELY TO BE
EVEN COLDER. MEANWHILE, SOME VERY SHALLOW, ALMOST TRANSLUCENT
CUMULUS CLOUDS HAVE DEVELOPED THIS AFTERNOON, AND A FEW VERY LIGHT
FLURRIES HAVE BEEN OBSERVED AS WELL. NO ACCUMULATIONS HAVE BEEN
REPORTED FROM THIS MORNING FLURRY ACTIVITY, ALTHOUGH THERE WERE
SOME REPORTS OF A VERY LIGHT DUSTING OF SNOW ACROSS SOUTHEAST
MISSOURI OVERNIGHT.
OVERNIGHT, HIGH PRESSURE WILL SLIDE ACROSS OUR SOUTHERN AREAS AND
THE SURFACE PRESSURE GRADIENT WILL RELAX. THIS WILL ALLOW OUR
CURRENTLY GUSTY WINDS TO WEAKEN AND REDUCE IT'S IMPACT ON WIND
CHILLS. ON THE OTHER HAND THOUGH, THESE WEAKER WINDS AND EXPECTED
CLEAR SKIES WILL PROMOTE MORE EFFICIENT RADIATIONAL COOLING
OVERNIGHT, NOT TO MENTION WE WILL BE WITHIN THE CORE OF THIS MOST
RECENT SURGE OF ARCTIC AIR. AS SUCH, WHAT WE LACK IN WIND WE WILL
MAKE UP FOR IN ACTUAL TEMPERATURES, AND THE END RESULT WILL BE
SIMILAR WIND CHILLS OVERNIGHT. WITH THE NEW WIND CHILL CRITERIA
IN PLACE, WE HAVE MAINTAINED A COLD WEATHER ADVISORY ACROSS PARTS
OF SOUTH-CENTRAL ILLINOIS OVERNIGHT, WERE WE EXPECT WIND CHILLS TO
REACH NEAR OR SLIGHTLY BELOW -10 DEGREES.
DURING THE DAY TOMORROW, THE BRIEF RESPITE FROM ACTIVE COLD AIR
ADVECTION AND MODEST DAYTIME HEATING SHOULD ALLOW FOR A VERY SLIGHT
IMPROVEMENT IN TEMPERATURES DURING THE DAY, WITH AN EMPHASIS ON
SLIGHT. WIND CHILLS ARE ONLY LIKELY TO RISE TO BETWEEN 0 AND 15
DEGREES (WITH ACTUAL TEMPERATURES BETWEEN 15 AND 25), WHICH WILL BE
AN IMPROVEMENT BUT CERTAINLY NOT ENOUGH TO START PACKING AWAY THE
HATS AND GLOVES.
THIS LATTER POINT WILL ONLY BE REINFORCED OVERNIGHT MONDAY AS
ANOTHER SURGE OF ARCTIC AIR WILL ARRIVE FROM THE NORTH. THIS
SECOND (AND FINAL) ROUND OF VERY COLD AIR WILL PLUNGE ACTUAL
TEMPERATURES DOWN TO THEIR LOWEST VALUES OF THIS EVENT OR VERY
CLOSE TO IT, ALONG WITH MODEST NORTHWESTERLY WINDS. TEMPERATURES
HAVE TRENDED VERY SLIGHTLY LOWER IN RECENT GUIDANCE AND CONFIDENCE
IS INCREASING THAT MONDAY NIGHT / TUESDAY MORNING WILL REQUIRE
ANOTHER COLD AIR ADVISORY IN SUBSEQUENT FORECASTS. WE HAVE NOT
ISSUED AN ACTUAL HEADLINE JUST YET IN AN EFFORT TO AVOID MIXING UP
THE MESSAGE WITH TONIGHT'S HEADLINE, BUT IT'S LIKELY THAT WE WILL
NEED ANOTHER TO REPLACE IT, AND OVER A BROADER AREA. WE MAY ALSO
SEE ANOTHER ROUND OF LIGHT FLURRY ACTIVITY AS WELL THANKS TO THE
RESUMPTION OF CYCLONIC FLOW AND THE PASSAGE OF ANOTHER SHORTWAVE.
AGAIN, NO SNOW ACCUMULATIONS ARE EXPECTED.
AS THE CORE OF THE COLD AIR AND HIGH PRESSURE SETTLES INTO THE AREA
DURING THE DAY TUESDAY, TEMPERATURES WILL STRUGGLE INTO THE TEENS
AND PERHAPS ONLY THE SINGLE DIGITS DURING THE AFTERNOON, ALTHOUGH
WIND SPEEDS ARE LIKELY TO WEAKEN SLOWLY AS WELL. IN ANY CASE IT WILL
REMAIN VERY COLD, BUT LIKELY WILL WARM JUST ENOUGH TO PULL US ABOVE
OUR COLD ADVISORY HEADLINE CRITERIA BY THE AFTERNOON. PRECIPITATION
IS ALSO NOT EXPECTED DURING THE DAY TUESDAY.
BRC
LONG TERM
(TUESDAY THROUGH NEXT SUNDAY)
ISSUED AT 231 PM CST SUN JAN 19 2025
WHILE WEDNESDAY MORNING IS EXPECTED TO BE QUITE COLD AGAIN, WE WILL
START TO SEE HINTS OF A PATTERN CHANGE AS LIGHT SOUTHERLY LOW LEVEL
FLOW GRADUALLY RESUMES. THIS WILL BE IN RESPONSE TO A DEEPENING
CENTRAL PLAINS TROUGH OF LOW PRESSURE, WHICH WILL SLOWLY APPROACH
THE AREA OVERNIGHT TUESDAY AND ARRIVE DURING THE DAY WEDNESDAY. THIS
WILL DRIVE WARM AIR ADVECTION ACROSS THE AREA, AND AS A RESULT,
TEMPERATURES ARE EXPECTED TO MODERATE QUICKLY BY WEDNESDAY
AFTERNOON. WHILE THIS WON'T EXACTLY LEAD TO BEACH WEATHER, WE ARE
LIKELY TO SEE MUCH MORE SEASONABLE AND EVEN SLIGHTLY ABOVE FREEZING
VALUES IN MANY AREAS. WEDNESDAY AFTERNOON. ENSEMBLE TEMPERATURE
SPREAD REMAIN RELATIVELY NARROW ON WEDNESDAY, WHICH ADDS CONFIDENCE
TO THE TEMPERATURE FORECAST IN SPITE OF THE 20+ DEGREE JUMP OVER 24
HOURS.
LATE IN THE WORKWEEK, CONFIDENCE CONTINUES TO INCREASE THAT ANOTHER
SHORTWAVE WILL DIG INTO THE AREA, WHICH WILL LIKELY SLOW OUR WARMING
TREND BUT WITHOUT PLUNGING US BACK INTO AN ARCTIC AIRMASS. THIS
FEATURE DOES SEEM TO PRESENT SOME VARIABILITY IN THE TEMPERATURE
FORECASTS AMONG ENSEMBLE MEMBERS THURSDAY AND FRIDAY, BUT THIS
VARIATION IS NOT ENOUGH TO CAUSE CONCERN THAT WE COULD SEE ANOTHER
ROUND OF COLD ANYWHERE CLOSE TO WHAT WE'RE SEEING NOW. INSTEAD, IT'S
MUCH MORE LIKELY THAT WE WILL HOVER AROUND SEASONAL NORMALS THROUGH
THE END OF THE WEEK, AND PERHAPS EVEN RESUME A SLIGHT WARMING TREND
BY THE WEEKEND.
MEANWHILE, PRECIPITATION CONTINUES TO BE ONLY SPARSELY REPRESENTED
AMONG ENSEMBLE MEMBERS OVER THE NEXT 7 DAYS, BUT THERE IS A VERY
MODEST SIGNAL FOR LIGHT PRECIPITATION OVERNIGHT WEDNESDAY THROUGH
THURSDAY AS THE PREVIOUSLY MENTIONED SHORTWAVE MOVES THROUGH THE
AREA. THIS IS ESPECIALLY THE CASE IN THE LREF ENSEMBLE SUITE, AND
SEEMS TO BE FOCUSED WITHIN GEFS AND GEPS MEMBERS IN PARTICULAR. THE
OPERATIONAL NBM REMAINS VERY PESSIMISTIC ABOUT THIS POTENTIAL, BUT
GIVEN THE SLIGHT INCREASE IN THE LREF SIGNAL WE CAN'T RULE OUT SOME
LIGHT PRECIPITATION WEDNESDAY NIGHT THROUGH THURSDAY. WE HAVE LEFT
THE MAJORITY OF THE FORECAST DRY ASIDE FROM A FEW COUNTIES WHERE 20%
PRECIPITATION CHANCES HAVE CREPT IN, BUT WE WILL NEED TO KEEP AN EYE
ON THIS TIMEFRAME IN CASE THIS SIGNAL CONTINUES TO INCREASE. LONGER
RANGE GUIDANCE ALSO HAS BEGUN TO HINT AT A MORE ACTIVE PATTERN
RESUMING OVER THE WEEKEND, BUT CONFIDENCE REMAINS VERY LOW REGARDING
THIS POTENTIAL AT THIS TIME.
BRC
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1008 PM CST SUN JAN 19 2025
DRY AND VFR FLIGHT CONDITIONS WILL CONTINUE THROUGH THE END OF THE
TAF PERIOD UNDER NORTHWESTERLY WINDS. WINDS WILL INCREASE IN SPEED
TOMORROW TO AROUND 10 KTS. WHILE GUSTS INTO THE LOW 20S ARE
POSSIBLE AT THE CENTRAL MISSOURI SITES DURING THE AFTERNOON,
CONFIDENCE ISN'T HIGH ENOUGH TO INCLUDE A MENTION OF THIS IN THE
TAF AT THIS POINT.
DELIA
LSX WATCHES/WARNINGS/ADVISORIES
MO...NONE.
IL...NONE.
WFO LSX
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