776
FXUS63 KILX 161745
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
1145 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
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 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1145 AM CST THU JAN 16 2025
MAIN POTENTIAL IMPACT OVER THE NEXT 24 HOURS IS POTENTIAL FOR FOG
DEVELOPMENT TONIGHT INTO FRIDAY MORNING. HAVE INCLUDED A MENTION
AT KSPI, KDEC, AND KCMI WHERE DEEPER SNOW WILL ENHANCE POTENTIAL
FOR FOG AND GUIDANCE IS MORE CONSISTENT WITH FOG DEVELOPMENT.
WINDS NW 12-18 KTS WITH GUSTS 20-25 KTS THIS AFTERNOON, BECOMING
LIGHT AND VARIABLE FOR A FEW HOURS THIS EVENING, THEN INCREASING
FROM THE SOUTH, AROUND 10 KTS THROUGH THE NIGHT, THEN INCREASING
TO 15-20 KTS WITH GUSTS AROUND 25 KTS BY 15Z.
37
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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