238
FXUS63 KILX 160808
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
208 AM CST THU JAN 16 2025
KEY MESSAGES
- PATCHY FREEZING FOG REMAINS A POSSIBILITY LATE TONIGHT IN AREAS
SOUTH OF A MACOMB TO DANVILLE LINE, THOUGH FORECAST CONFIDENCE
IS BELOW 50%.
- A BRIEF WARM-UP WILL CLOSE OUT THIS WEEK, PRECEDING ANOTHER SHOT
OF VERY COLD TEMPERATURES BY THE WEEKEND. THERE IS A HIGH
CONFIDENCE (60% CHANCE OR GREATER) IN WIND CHILL VALUES COLDER
THAN 10 BELOW ZERO SUNDAY NIGHT & MONDAY NIGHT.
- RAIN IS LIKELY (60% CHANCE OR GREATER) FRIDAY NIGHT EAST OF THE
ILLINOIS RIVER VALLEY. A TRANSITION TO LIGHT SNOW WILL OCCUR BY
SATURDAY MORNING, BUT THE PROBABILITY OF ACCUMULATING SNOW IS
LOW (30% CHANCE OR LESS).
DISCUSSION
(THROUGH NEXT THURSDAY)
ISSUED AT 1229 AM CST THU JAN 16 2025
THE UPPER-LEVEL PATTERN REMAINS AMPLIFIED THIS MORNING, WITH WATER
VAPOR IMAGERY DEPICTING A RIDGE AXIS PUSHING ACROSS THE NORTHERN
ROCKIES. WITH DEEP DOWNSLOPE FLOW SPREADING EASTWARD ACROSS THE
NORTHERN PLAINS AND UPPER MIDWEST, THE EFFECTS OF COMPRESSIONAL
WARMING HAVE HELPED BOOST UPSTREAM TEMPERATURES INTO THE 30S.
THESE MILD CONDITIONS WILL REACH CENTRAL ILLINOIS THIS AFTERNOON,
PROVIDING A 10-15 DEGF JUMP IN TEMPERATURES FROM YESTERDAY.
AS THE RIDGE AXIS PUSHES EAST OF THE MISSISSIPPI VALLEY THIS
EVENING AND LOW- LEVEL WINDS TURN SOUTHERLY AND INCREASE AHEAD OF
A FRONTAL SYSTEM, WE MAY BEGIN TO SEE THE DEVELOPMENT OF ADVECTION
FOG, PRIMARILY IN AREAS ALONG AND SOUTH OF I-72 WHERE WE'LL BE
CLINGING ONTO A RESIDUAL SNOWPACK. MODEL SOUNDINGS, PARTICULARLY
THE HI-RES BUT ALSO A FEW OF THE GLOBALS, DO SHOW A PINCH OF
MOISTURE TRAPPED BENEATH A STRENGTHENING SFC-0.5KM INVERSION. A
QUICK GLANCE AT THE PROBABILISTIC HREF SUPPORTS A MEDIUM
CONFIDENCE (40-60% CHANCE) IN VISIBILITY BELOW ONE-HALF MILE
BETWEEN 03Z-15Z. WITH OVERNIGHT TEMPERATURES IN THE MID 20S, ANY
FOG THAT DOES DEVELOP WILL BE FREEZING FOG. WE WILL CONTINUE TO
MONITOR HOURLY FORECAST GUIDANCE AND UPSTREAM TRENDS BEFORE BITING
ON A FREEZING FOG ADVISORY FOR TONIGHT.
A PLUME OF MOISTURE WILL SURGE NORTHWARD FROM THE GULF FRIDAY
AFTERNOON AHEAD OF DEEPENING SOUTHWEST FLOW. AS A PAIR OF
SHORTWAVES BEGIN TO PHASE OVER THE CENTRAL U.S. BY FRIDAY EVENING,
THEY WILL HELP FORCE A SURFACE COLD FRONT ACROSS THE AREA. MODEL
SOUNDINGS AHEAD OF THE FRONT SUPPORT RAIN AT THE ONSET, THEN
BRIEFLY TRANSITIONING TO SNOW BY EARLY SATURDAY MORNING AS THE
FRONT DEPARTS. THE PROBABILITY FOR ACCUMULATING SNOW ON THE
BACKSIDE IS LOW (ABOUT 30% OR LESS) AND WOULD BE CONFINED TO AREAS
EAST OF I-55.
THE HAMMER DROPS THIS WEEKEND AS A DRY ARCTIC AIRMASS SINKS
EQUATORWARD INTO THE CENTRAL U.S. AND DISPERSES 850-MB TEMPS
BETWEEN -24C AND -28C. WHILE THIS IS TRULY SOME RARE AIR (LOWEST 1
PERCENTILE OF MID-JANUARY CLIMATOLOGY), THE LACK OF A SNOWPACK
WILL HELP MITIGATE RECORD-LOW TEMPS. NEVERTHELESS, WE ARE
FORECASTING LOWS NEAR OR SLIGHTLY BELOW ZERO SUNDAY NIGHT AND
MONDAY NIGHT. DURING THIS TIMEFRAME, CONFIDENCE REMAINS HIGH (60%
CHANCE OR GREATER) IN WIND CHILL VALUES COLDER THAN TEN BELOW
ZERO.
TEMPERATURES DO BEGIN TO TREND WARMER AFTER MONDAY AS AN
AMPLIFIED RIDGE GRADUALLY BUILDS EASTWARD ACROSS THE ROCKIES. BY
THURSDAY, THERE IS GOOD SEMBLANCE AMONG GLOBAL ENSEMBLE GUIDANCE
FOR TEMPERATURES TO RETURN NEAR NORMAL (DAILY HIGHS IN THE 30S).
WHILE THE FORECAST FOR NEXT WEEK APPEARS DRY FOR NOW, IT WON'T
TAKE MUCH FOR US TO SQUEEZE- OUT SOME LIGHT SNOW MONDAY OR TUESDAY
AHEAD OF THE RIDGE AXIS; THOUGH COLUMN MOISTURE (RH) APPEARS
DISJOINTED ENOUGH FOR NOW TO KEEP MENTION OF FLURRIES OUT OF THE
FORECAST. FURTHERMORE, WE ARE NOTING QUITE A BIT OF NOISE IN THE
ENSEMBLE QPF BY LATE NEXT WEEK. WHILE THERE IS NO CLEAR SIGNAL
AMONG THE NOISE, THIS COULD BE OUR NEXT PERIOD TO WATCH FOR
IMPACTFUL WEATHER.
MJA
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1139 PM CST WED JAN 15 2025
VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES NEXT 24HRS. MID LEVEL
DECK IS MOVING ACROSS THE SITES BUT SHOULD BE OUT OF THE AREA BY
09-10Z. VERY LIGHT FLURRIES ARE POSSIBLE, BUT CHANCE IS SMALL
ENOUGH WILL NOT BE ADDED TO TAFS. ALL SITES WILL SCATTER OUT OR
CLEAR LATE TONIGHT AND CONTINUE INTO THE MORNING, BUT BMI WILL SEE
MID CLOUDS AROUND 8KFT COME BACK IN AT 14Z AND CMI WILL SEE MID
CLOUDS AROUND 10KFT AT 16Z. MID CLOUDS WILL PUSH DOWN INTO PIA BUT
NOT DEC AND SPI. THE MID CLOUDS SHOULD REMAIN ALONG I-74 WITH ONLY
SCATTER CLOUDS EXPECTED AT DEC AND SPI. CIG HEIGHTS WILL RISE TO
AROUND 15KFT AT PIA, BMI, AND CMI AFTER 00Z. WINDS WILL BE SOUTH-
SOUTHWEST OVERNIGHT, BUT BECOME SOUTHWEST IN SEVERAL HOURS...THEN
WESTERLY TOMORROW MORNING AS THE TROUGH/FRONT MOVES THROUGH THE
AREA. WIND SPEEDS WILL BE BREEZY, REACHING GUSTS OF 24-25 KTS AT
ALL SITES EXCEPT PIA DURING THE MORNING AND AFTERNOON HOURS. WINDS
BECOME LIGHT IN THE EVENING.
AUTEN
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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