576
FXUS63 KLOT 181735
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1135 AM CST SUN JAN 18 2026
KEY MESSAGES
- ACCUMULATING SNOW IS EXPECTED LATE THIS AFTERNOON INTO THIS
EVENING, WITH SLIPPERY TRAVEL CONDITIONS EXPECTED.
- A STRONG ARCTIC COLD FRONT WILL MOVE ACROSS THE AREA LATE THIS
EVENING WITH WEST NORTHWEST WINDS GUSTING TO 40 MPH. SOME
BLOWING SNOW WILL BE POSSIBLE.
- BITTERLY COLD CONDITIONS ARE EXPECTED LATE TONIGHT THROUGH
TUESDAY MORNING WITH WIND CHILLS 15 BELOW TO 25 BELOW ZERO
EXPECTED MONDAY MORNING.
- A CLIPPER SYSTEM MAY BRING ACCUMULATING SNOW TO PARTS OF THE
AREA TUESDAY NIGHT INTO WEDNESDAY MORNING.
DISCUSSION
ISSUED AT 220 AM CST SUN JAN 18 2026
A STRONG ARCTIC COLD FRONT WILL MOVE ACROSS THE AREA LATE THIS
EVENING INTO THE EARLY OVERNIGHT HOURS. AHEAD OF THIS FRONT, A
PERIOD OF SNOW IS EXPECTED TO SPREAD ACROSS THE AREA STARTING IN
THE LATE AFTERNOON AND CONTINUING THROUGH MID/LATE EVENING, WITH
THE FOCUS FOR SNOW ALONG AND NORTH OF A LASALLE TO RENSSELAER
LINE. UNLIKE THE SYSTEM SATURDAY EVENING THAT WAS EXPECTED AND
DID WEAKEN AS IT MOVED ACROSS THE AREA, THIS SYSTEM WILL LIKELY
CONTINUE PRODUCING SNOW AS MOVES ACROSS THE ENTIRE AREA AND WITH
THE DRY/COLD AIRMASS IN PLACE, FLUFFY DRY SNOW MAY RESULT IN AN
INCH OF SNOW ACCUMULATION, PERHAPS 1-2 INCHES ACROSS PARTS OF
NORTHEAST IL. THE ACCUMULATING SNOW LOOKS TO END AS THE COLD
FRONT ARRIVES BUT THERE MAY STILL BE A PERIOD OF FLURRIES OR
SNOW SHOWERS INTO THE EARLY OVERNIGHT HOURS.
WINDS BEHIND THE COLD FRONT WILL QUICKLY INCREASE INTO THE 20-30
MPH RANGE WITH GUSTS 35-40 MPH POSSIBLE. ITS UNCLEAR HOW MUCH
BLOWING SNOW MAY OCCUR WITH THE EXPECTATION THAT MOST, IF NOT
ALL THE FALLING SNOW WILL BE OVER. MORE LIKELY IS LOW DRIFTING
SNOW, PRESENTING ISSUES FOR NORTH/SOUTH ROADS IN OPEN AREAS.
OPTED NOT TO INCLUDE ANY BLOWING SNOW IN THE FORECAST/GRIDS, BUT
THIS WILL NEED TO BE LOOKED AT AGAIN WITH LATER FORECASTS.
HIGH TEMPS TODAY MAY STRUGGLE TO REACH 20, HOLD STEADY FOR A FEW
HOURS DURING THE SNOW, THEN STEADILY FALL BEHIND THE FRONT WITH
LOW TEMPS BY DAYBREAK MONDAY MORNING AROUND ZERO OR A FEW
DEGREES BELOW ZERO ACROSS THE NORTHWEST CWA, TO THE LOW SINGLE
DIGITS FOR THE REST OF THE AREA. WITH WINDS STILL EXPECTED TO BE
IN THE 20-25 MPH RANGE, WITH HIGHER GUSTS, THIS WILL ALLOW WIND
CHILLS IN THE 20 BELOW TO 25 BELOW RANGE FOR MOST OF OUR IL
COUNTIES. WIND CHILLS FOR CHICAGO AND ALONG/EAST OF I-57 MAY BE
MORE IN THE 15 BELOW TO 20 BELOW ZERO RANGE. OPTED TO DRAW THE
BOUNDARY FOR THE COLD WEATHER ADVISORY ALONG THE IL/IN STATE
LINE, THOUGH AS NOTED, MARGINAL CRITERIA ON THE FAR EASTERN
EDGE OF THE ADVISORY. HIGH TEMPS MONDAY ONLY REBOUND INTO THE
MID/UPPER SINGLE DIGITS FOR MOST AREAS, PERHAPS SOME LOW TEENS
ACROSS CENTRAL IL. WIND CHILLS ARE EXPECTED TO REMAIN BELOW ZERO
ALL DAY MONDAY, MONDAY NIGHT AND INTO TUESDAY MORNING. SIMILAR
LOW TEMPS ARE EXPECTED AGAIN TUESDAY MORNING, BUT WITH LOWER
WIND SPEEDS, WIND CHILLS LOOK TO BE IN THE 10 BELOW TO 15 BELOW
RANGE.
ONE CHANGE TO THE FORECAST THAT WILL NEED TO BE WATCHED IS
ANOTHER WEAK WAVE THAT MOVES ACROSS THE REGION LATE MONDAY
AFTERNOON INTO MONDAY EVENING. MODELS ARE DRY WITH THIS FEATURE,
AS IS THE BLENDED GUIDANCE, BUT IF THIS MATERIALIZES IN THE VERY
COLD AIRMASS, THERE MAY AT LEAST BE SOME FLURRIES.
MODELS REMAIN IN OVERALL GOOD AGREEMENT WITH A CLIPPER SYSTEM
FOR TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING WITH A CHANCE FOR
ACCUMULATING SNOW ACROSS AT LEAST FAR NORTHERN IL. STILL A FEW
DAYS AWAY AND SNOW LOCATION/AMOUNTS WILL BE DEPENDENT ON THE
EXACT TRACK, BUT OVERALL, THIS HAS BEEN A WELL HANDLED FEATURE
AMONG THE MODELS FOR SEVERAL DAYS. ANOTHER FEATURE OF NOTE IS A
COLD FRONT LATE WEDNESDAY OR WEDNESDAY NIGHT, THAT MAY BRING
ANOTHER PERIOD OF FLURRIES OR SNOW SHOWERS.
TEMPS STILL LOOK TO BRIEFLY MODERATE WEDNESDAY, AHEAD OF THE
CLIPPER SYSTEM WHEN HIGHS MAY REACH THE UPPER 20S/LOWER 30S.
THERE REMAINS QUITE A BIT OF UNCERTAINTY FOR THE END OF THE
WEEK INTO THE WEEKEND WITH THE POTENTIAL FOR AN ACTIVE PATTERN
FOR OR NEAR THE LOCAL AREA. THE ENSEMBLES SEEM TO BE IN A
LITTLE BETTER AGREEMENT FOR PRECIPITATION CHANCES FOR THE LOCAL
AREA, BUT THERE IS STILL A DECENT SPREAD IN POSSIBILITIES.
REGARDLESS OF WHETHER PRECIP DEVELOPS FOR THE LOCAL AREA,
CURRENT TRENDS CONTINUE TO FAVOR A COLD/VERY COLD PATTERN. CMS
AVIATION /18Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 1135 AM CST SUN JAN 18 2026
FORECAST CONCERN FOR THE TERMINALS...
- PERIOD OF ACCUMULATING SNOW THIS EVENING RESULTING IN IFR
VISIBILITIES AND MVFR CEILINGS.
- ARCTIC FRONT TO BRING GUSTY NORTHWEST WINDS TONIGHT GUSTING
30-35 KTS INTO MONDAY MORNING.
- LINGERING FLURRIES OVERNIGHT WITH A 20% CHANCE FOR SNOW
SHOWERS AND BLOWING SNOW WHICH MAY RESULT IN LOCALLY REDUCED
VISIBILITIES.
NORTHERN IL AND NORTHWEST IN CURRENTLY RESIDE IN THE SINKING AIR
BEHIND LAST NIGHT'S DISTURBANCE WHICH HAS ALLOWED FOR SCT TO BKN
VFR SKIES TO PREVAIL THIS MORNING. THAT SAID, CLOUD COVER WILL
CONTINUE TO INCREASE THROUGH THE AFTERNOON AS THE DISTURBANCE
OVER MN AND THE DAKOTAS CONTINUES TO PIVOT TOWARDS THE AREA.
WINDS THIS AFTERNOON WILL ALSO REMAIN BLUSTERY WITH 20-25 KT
GUSTS OUT OF THE WEST-SOUTHWEST.
HEADING INTO THIS EVENING, THE AFOREMENTIONED DISTURBANCE WILL
BEGIN TO MOVE INTO THE AREA AND BRING WITH IT A PERIOD OF STEADY
SNOW AND MVFR CEILINGS. THE LATEST FORECAST GENERALLY REMAINS
UNCHANGED WITH LIGHT SNOW/FLURRIES EXPECTED TO BEGIN AROUND
21-22Z (EARLIEST AT RFD) WITH THE TRUE STEADY SNOW AND REDUCED
VISIBILITY BEGINNING AROUND 23-00Z. THOUGH, THERE REMAINS SOME
UNCERTAINTY AS TO HOW QUICKLY THE ATMOSPHERE WILL SATURATE SO
THE STEADY SNOW ONSET COULD VERY BY ABOUT AN HOUR. ONCE SNOW
BEGINS, A 3-4 HOUR PERIOD OF IFR (1-2SM) VISIBILITY IS EXPECTED
AT THE TERMINALS WITH SOME ACCUMULATION LIKELY GIVEN THE COLD
TEMPERATURES IN THE TEENS TO AROUND 20F. SO EXPECT TOTAL
ACCUMULATIONS AROUND 0.5 TO 1.0 INCH, BUT LOCALLY HIGHER AMOUNTS
UP TO 2 INCHES MAY BE SEEN NEAR AND NORTH OF A RFD TO PWK LINE.
THE STEADIER SNOW WILL BEGIN TO SHIFT EAST AROUND 03-04Z THIS
EVENING WITH JUST LINGERING FLURRIES EXPECTED FOR THE REST OF
THE OVERNIGHT PERIOD. HOWEVER, GUIDANCE IS HINTING AT SOME
CONVECTIVE SNOW SHOWERS DEVELOPING OVERNIGHT ALONG THE ARCTIC
FRONT WHICH COULD BRIEFLY RESULT IN REDUCED VISIBILITIES
(1-3SM). GIVEN THE SCATTERED NATURE OF THESE SNOW SHOWERS, AND
LOW CONFIDENCE ON IF THEY WILL IMPACT THE TERMINALS (15-20%
CHANCE) HAVE OPTED TO FOREGO A FORMAL MENTION IN THE TAFS FOR
NOW. REGARDLESS, WINDS WILL BECOME GUSTY BEHIND THE FRONT WITH
NORTHWEST GUSTS AROUND 30-35 KT EXPECTED OVERNIGHT INTO MONDAY
MORNING. NOT ONLY WILL THESE WINDS RESULT IN BITTERLY COLD
WIND CHILLS OF -15F TO -25F, THEY MAY ALSO LEAD TO INSTANCES OF
BLOWING AND DRIFTING SNOW TONIGHT. THOUGH WITH THE LACK OF A
FORMIDABLE SNOW PACK (CURRENT SNOW DEPTHS GENERALLY <1 INCH),
CONFIDENCE ON THE AMOUNT OF BLOWING/DRIFTING SNOW IS LOW AND
THUS WAS ALSO LEFT OUT OF THE TAFS FOR NOW.
ANY LINGERING FLURRIES ARE EXPECTED TO DIMINISH MONDAY MORNING
AS CLOUD DEPTHS DECREASE. THOUGH, MVFR CEILINGS ARE EXPECTED TO
PERSIST THROUGH AT LEAST MIDDAY BEFORE SKIES ATTEMPT TO SCATTER
OUT. WINDS WILL ALSO GRADUALLY DIMINISH THROUGH THE DAY ON
MONDAY, BUT WEST-NORTHWEST GUSTS IN 20-30 KT RANGE CAN BE
EXPECTED THROUGH THE END OF THE TAF PERIOD.
YACK
MARINE
ISSUED AT 220 AM CST SUN JAN 18 2026
THE GALE WATCH HAS BEEN UPGRADED TO A GALE WARNING FOR TONIGHT
INTO MONDAY MORNING FOR ALL OF THE IL AND IN NEARSHORE WATERS.
A HEAVY FREEZING SPRAY WARNING HAS BEEN ISSUED FOR THE
NEARSHORE WATERS EAST OF GARY, IN.
A STRONG ARCTIC COLD FRONT WILL MOVE ACROSS THE AREA TONIGHT,
BRINGING A PERIOD OF GALE FORCE WINDS BETWEEN 35 AND 40 KNOTS.
THESE STRONG WINDS WILL SLOWLY DIMINISH ON MONDAY WITH GALES
ENDING ACROSS THE IL NEARSHORE MONDAY MORNING AND THEN ACROSS
THE IN NEARSHORE MONDAY AFTERNOON. VERY COLD TEMPERATURES WILL
SPREAD ACROSS THE AREA BEHIND THIS COLD FRONT AND COMBINED WITH
THE HIGH WAVES, HEAVY FREEZING SPRAY IS EXPECTED ACROSS PARTS OF
THE IN NEARSHORE WATERS, MAINLY EAST OF GARY, IN. CMS
HYDROLOGY
ISSUED AT 253 PM CST FRI JAN 16 2026
THE UPCOMING EXTENDED PERIOD OF VERY COLD TEMPERATURES WILL LIKELY
RESULT IN THE RAPID DEVELOPMENT OF ICE ON AREA RIVERS AND STREAMS
WHICH MAY INCREASE THE CHANCE OF LOCALIZED ICE JAM FLOODING. LAST
WEEK'S HEAVY RAINFALL HAS RESULTED IN INCREASED STREAMFLOW IN
SEVERAL BASINS, INCLUDING THE FOX, DES PLAINS, AND ILLINOIS RIVER
BASINS. THIS HIGHER STREAMFLOW WILL RESULT IN A GREATER POTENTIAL
FOR FREEZE UP ICE JAM FLOODING.
- IZZI
LOT WATCHES/WARNINGS/ADVISORIES
IL...COLD WEATHER ADVISORY FROM 3 AM TO 10 AM CST MONDAY FOR ILZ003-
ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-
ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ103-
ILZ104-ILZ105-ILZ106-ILZ107-ILZ108.
IN...NONE.
LM...GALE WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST MONDAY FOR
WINTHROP HARBOR IL TO GARY IN.
GALE WARNING FROM MIDNIGHT TONIGHT TO 3 PM CST MONDAY FOR GARY
TO BURNS HARBOR IN-BURNS HARBOR TO MICHIGAN CITY IN.
HEAVY FREEZING SPRAY WARNING FROM MIDNIGHT TONIGHT TO 3 PM CST
MONDAY FOR GARY TO BURNS HARBOR IN-BURNS HARBOR TO
MICHIGAN CITY IN.
VISIT US AT WEATHER.GOV/CHICAGO
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