650
FXUS63 KLOT 150535
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1135 PM CST WED JAN 14 2026
KEY MESSAGES
- LAKE EFFECT SNOW--HEAVY AT TIMES--WILL IMPACT PARTS OF PORTER
AND JASPER COUNTIES TONIGHT INTO THURSDAY MORNING. POTENTIAL
FOR THE MAIN BAND TO IMPACT PARTS OF EASTERN PORTER COUNTY
EARLY THURSDAY MORNING WITH 2-3 INCH/HOUR SNOWFALL RATES.
- ACCUMULATING SNOW IS EXPECTED THURSDAY NIGHT, LIKELY RESULTING
IN HAZARDOUS CONDITIONS.
- THURSDAY NIGHT SYSTEM WILL BE JUST ONE OF MANY CLIPPER-LIKE
SYSTEMS RIDING THE NORTHWEST FLOW ACROSS THE REGION BRING
OCCASIONAL CHANCES FOR SNOW, EACH FOLLOWED BY VERY COLD AND
WINDY CONDITIONS.
UPDATE
ISSUED AT 1005 PM CST WED JAN 14 2026
A WELL-ORGANIZED PRIMARY DOMINANT LAKE EFFECT SNOW BAND
CONTINUES TO PRODUCE EXTREMELY HEAVY SNOWFALL IN THE VICINITY
OF A SOUTH HAVEN, MI TO SOUTH BEND/PLYMOUTH, IN LINE AT THIS
TIME. LES PARAMETERS WILL BE MAXIMIZING THROUGH LATE THIS
EVENING AND OVERNIGHT. BASED ON RECENT RADAR RETURNS, LAKE-
INDUCED EQUILIBRIUM HEIGHTS APPEAR TO BE PUSHING NORTH OF 10
KFT, ESSENTIALLY IN LINE WITH RECENT BUFKIT OUTPUT FROM THE
HRRR/RAP. ALONG THE WESTERN FLANKS OF THIS PRIMARY BAND, MORE
DISORGANIZED/CELLULAR LES WILL CONTINUE STREAMING ACROSS PORTER
AND FAR EASTERN LAKE/NE JASPER COUNTIES, WITH INTERMITTENT AND
EMBEDDED HIGHER RATES. THROUGH ABOUT 1 AM, THE FORECAST REMAINS
IN GOOD SHAPE WITH MINIMAL CHANGES NEEDED.
THE MAIN CONCERN IS A RECENT/ONGOING WESTWARD TREND IN THE HIGH-
RES MODEL SUITE, WITH INDICATIONS THAT THE MAIN/DOMINANT LES
BAND MAY ATTEMPT TO PUSH INTO PARTS OF EASTERN PORTER COUNTY AND
EXTREME NE JASPER COUNTY VERY LATE TONIGHT INTO EARLY THURSDAY
MORNING. WHILE THE GENERAL LARGE SCALE FEATURES ARE ALL MORE-OR-
LESS THE SAME ACROSS THE GUIDANCE SUITE (AS YOU'D EXPECT AT
THIS TIME RANGE), A SUBTLE DIFFERENCE IN THE MORE WESTERLY
GUIDANCE SEEMS TO BE THE DEGREE OF MODELED CLEARING ACROSS THE
LAKE ADJACENT AREAS OF WESTERN LOWER MICHIGAN, COUPLED WITH AT
LEAST SOME INFLUENCE OF A SECONDARY MID-LEVEL TROUGH AXIS
CURRENTLY PIVOTING OVERHEAD. THE RESULTING COOLING OVERNIGHT
(TEMPERATURES FALLING INTO THE SINGLE DIGITS AND TEENS), COMBINED
WITH A VERY SUBTLE VEERING OF THE 850-800 MB FLOW IN TURN APPEARS
TO BE DRIVING AN INCREASED LAND BREEZE COMPONENT ALONG WITH A
GENERAL SHARPER VEERING OF THE SURFACE FLOW TO NORTHEASTERLY ON
THE EASTERN SIDE OF THE LAKE WHICH SUBSEQUENTLY SENDS THE MAIN LES
BAND STEADILY WESTWARD.
THESE MESOSCALE-LEVEL ASPECTS ARE NEVER EASY TO NAIL DOWN, AND
THERE'S STILL A DECENT SPREAD ACROSS THE GUIDANCE SUITE. HOWEVER,
GIVEN THE CONTINUED SHIFTING WITH SOME OF THE GUIDANCE, GROWING
MORE CONCERNED ABOUT VERY HIGH SNOWFALL RATES EITHER MAKING IT
INTO PARTS OF PORTER COUNTY OR GETTING EXCEPTIONALLY CLOSE.
HOURLY RATES WITHIN THE MAIN BAND WOULD LIKELY PUSH 2-3"+ PER
HOUR WHICH WOULD OBVIOUSLY BE CRIPPLING TO THE EARLY-MORNING
COMMUTE IF THE BAND PERSIST THROUGH THE MORNING.
WITH WINDS NOW STARTING TO TURN NNE ACROSS PARTS OF LOWER
MICHIGAN AND THE EXTREMELY CLOSE NATURE OF THINGS, FELT THE
MOST PRUDENT MOVE WAS TO UPGRADE PORTER COUNTY TO A WINTER STORM
WARNING AND BOOST SNOWFALL AMOUNTS RIGHT ON THE COUNTY LINE/FAR
EASTERN PARTS OF THE COUNTY, BUT HAVE NOT TOTALLY COMMITTED TO
THE EXTREME SOLUTION ADVERTISED BY THE RECENT HRRR RUNS. DID
ALSO ADD JASPER AS AN ADVISORY WITH ONGOING SNOW SHOWERS FILLING
IN FROM THE EAST, WITH OVERALL AMOUNTS FORECAST MAINLY IN THE
1-4 INCH RANGE ACROSS THE NORTHEASTERN QUADRANT OF THE COUNTY.
CARLAW
DISCUSSION
ISSUED AT 238 PM CST WED JAN 14 2026
THROUGH THURSDAY:
ONGOING SCATTERED SNOW SHOWERS ACROSS MUCH OF NORTHERN ILLINOIS
AND NORTHWEST INDIANA WILL END FROM NORTHWEST TO SOUTHEAST LATE
THIS AFTERNOON THROUGH EARLY EVENING AS THE MAIN MID-LEVEL
TROUGH AXIS CROSSES THE AREA. DIURNAL ENHANCEMENT OF THE SHOWERS
HAS ALLOWED FOR SOME BURSTS OF SNOW WITH VISIBILITY UNDER A
HALF MILE AND BRIEF ACCUMULATIONS OF A COUPLE TENTHS. HOWEVER,
THESE STRONGER SHOWERS ARE A BIT MORE ISOLATED AND WILL BEGIN
WANING WITH THE LOSS OF DAYTIME HEATING OVER THE NEXT COUPLE
HOURS.
LAKE EFFECT SNOW WILL THEN TAKE HOLD OVER SOUTHERN LAKE
MICHIGAN TONIGHT THROUGH THURSDAY MORNING AS INVERSION HEIGHTS
RISE AND THE ENTIRE DGZ SETTLE THROUGH THE MIDDLE OF THE
CONVECTIVE CLOUD DEPTH. WHILE LES IS POSSIBLE AT ANY TIME
THROUGH THURSDAY MORNING, THERE AREA TWO PERIODS OF FOCUS WHEN
COVERAGE AND INTENSITY ARE EXPECTED TO BE HIGHER.
1) VERY LATE THIS AFTERNOON INTO MID-EVENING BEHIND THE PASSING
TROUGH, CONTINUED CAA THROUGHOUT A GRADUALLY DEEPER LAYER WILL
STEEPEN LOW-LEVEL LAPSE RATES AND RAISE INVERSION HEIGHTS AS
HIGH AS 8KFT. EXPECTATIONS ARE FOR A NOTABLE UPTICK IN SNOW
SHOWERS EAST OF I-65 AND ESPECIALLY OVER MUCH OF PORTER COUNTY,
WITH THE POTENTIAL FOR SNOWFALL RATES LOCALLY UP TO 1"/HR IF ANY
LES BAND REMAINS ANCHORED AT A GIVEN LOCATION FOR AN EXTENDED
PERIOD.
A MORE DOMINANT LES BAND SHOULD THEN SETTLE EAST OF PORTER
COUNTY FOR SEVERAL HOURS LATE THIS EVENING INTO THE OVERNIGHT
HOURS, WITH THE POTENTIAL FOR A WEAKER "SATELLITE" BAND TO THE
WEST DEVELOPING ALONG OFF THE ILLINOIS SHORE AND INTO NORTHEAST
LAKE AND NORTHERN PORTER COUNTY. ANY LAKE BREEZE COMPONENT OFF
NORTHEAST ILLINOIS WILL PROVIDE ADDED CONVERGENCE FOR THE WEAKER
WESTERN BAND.
2) WITH A SECONDARY, WEAKER WAVE CURRENTLY JUST NORTH OF LAKE
SUPERIOR EXPECTED TO TRACK SOUTHWARD ALONG LAKE MICHIGAN
TONIGHT, LOW-LEVEL FLOW MAY EVER-SO-SLIGHTLY VEER, PARTICULARLY
IN THE UPPER-HALF OF THE CONVECTIVE COLUMN, SUCH THAT THE
DOMINANT BAND EITHER BRUSHES THE PORTER/LAPORTE LINE OR EVEN
EDGES WESTWARD INTO EASTERN PORTER LATE TONIGHT THROUGH DAYBREAK
THURSDAY. CONFIDENCE IS LOW THAT THE BAND WILL SUBSTANTIALLY
AFFECT PORTER COUNTY, BUT HIGH ENOUGH THAT POPS AND QPF HAVE
BEEN NUDGED UPWARD DURING THIS PERIOD.
LES WILL DIMINISH MID TO LATE MORNING AS INVERSION HEIGHTS TO
LOWER, THEN END BY EARLY AFTERNOON AS LOW-LEVEL BEGINS VEERING
SW. OVERALL, EXPECT SNOWFALL TOTALS RANGING FROM 1 TO 3 INCHES
OVER FAR NORTHEAST LAKE COUNTY TO 3 TO 6 INCHES OVER FAR EASTERN
PORTER COUNTY. ON TOP OF THE SNOW, STRONG N/NNW WINDS WILL GUST
TO 50 MPH ALONG THE LAKE MICHIGAN SHORE AND 40 MPH INLAND,
PARTICULARLY THIS EVENING. BECAUSE OF THIS, THE COMBINATION OF
FALLING AND BLOWING SNOW WILL RESULT IN BRIEF PERIODS OF
WHITEOUT CONDITIONS. OPTED TO MAINTAIN A WINTER WEATHER ADVISORY
FOR PORTER COUNTY, THOUGH A QUICK UPGRADE TO A WINTER STORM
WARNING REMAINS POSSIBLE IF TRENDS SUPPORT THE MAIN BAND
SHIFTING BACK INTO THE AREA LATE TONIGHT. IN THIS SCENARIO,
LOCALIZED BLIZZARD CONDITIONS WOULD BE POSSIBLE.
KLUBER
THURSDAY NIGHT THROUGH WEDNESDAY:
ACTIVE NORTHWEST FLOW PATTERN IS EXPECTED THROUGH THE FIRST PART
OF NEXT WEEK WITH SEVERAL, POTENTIALLY VIGOROUS CLIPPER-LIKE
SYSTEMS LIKELY TO MOVE ACROSS THE REGION. EACH CLIPPER WILL
LIKELY LEAD TO WINDY CONDITIONS, SOME SNOW OR SNOW SHOWER
CHANCES, AND EACH FOLLOWED SIGNIFICANT SHOTS OF COLD AIR.
FIRST SYSTEM IS PROGGED TO DROP SOUTHEAST INTO THE MIDWEST
THURSDAY NIGHT. LOW AND MID LEVEL FLOW WILL BACK IN ADVANCE OF
THIS WAVE RESULTING IN STRONG ISENTROPIC ASCENT, MOST EVIDENT ON
THE 285-295K SURFACES, WHERE THE STRONGEST PRESSURE ADVECTION
IS NOTED. THE COMBINATION OF THE ISENTROPIC ASCENT AND DCVA IN
ADVANCE OF THE SHORTWAVE TROUGH SHOULD LEAD IN A NICE THUMPING
OF SNOW ACROSS THE REGION. IT LOOKS TO BE RATHER QUICK HITTING,
WITH 1-3" OF SNOW POSSIBLE WITH THIS SYSTEM.
TEMPERATURES SHOULD REMAIN GENERALLY STEADY THURSDAY NIGHT,
BEFORE WARM FRONT MOVES ACROSS THE AREA EARLY FRIDAY MORNING
BRING AN END TO THE SNOW AND SETTING US UP FOR A RELATIVELY MILD
DAY FRIDAY. OUR AREA WILL BE IN THE SYSTEM'S WARM SECTOR FRIDAY
PROBABLY ALLOWING HIGH TEMPERATURES TO CLIMB ABOVE FREEZING,
POSSIBLY FOR THE LAST TIME FOR A WHILE. OUR TIME IN THE WARM
SECTOR WILL BE SHORT LIVED AS ARCTIC FRONT WILL MOVE ACROSS THE
AREA FRIDAY NIGHT USHERING IN A MUCH COLDER AIR MASS.
DIFFERENCES BEGIN TO CREEP UP BETWEEN THE OPERATIONAL GFS AND
ECMWF OVER THE WEEKEND REGARDING TIMING OF THE NEXT COUPLE OF
CLIPPERS, INCLUDING ONE OVER THE WEEKEND. GENERALLY THE THEME OF
UNSETTLED CONDITIONS WITH OCCASIONAL CHANCES OF SNOW OR SNOW
SHOWERS, GUSTY WINDS, AND SOME TEMPERATURES SWINGS FROM
SEASONABLY COLD TO MUCH BELOW AVERAGE ARE LIKELY. THERE IS SOME
ENSEMBLE SUPPORT FOR A DUMP OF BITTERLY COLD AIR MAKING IT INTO
THE AREA IN THE WAKE OF THESE CLIPPERS EARLY NEXT WEEK, BUT
DETAILS IN THE TIMING AND JUST HOW COLD TEMPS GET WILL STILL
NEED TO BE FINE TUNED. IN THE MEANTIME, NO CHANGES WERE MADE TO
NBM OUTPUT FOR THE WEEKEND AND EARLY NEXT WEEK.
- IZZI
AVIATION /06Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 1135 PM CST WED JAN 14 2026
KEY MESSAGES:
- POOR QUALITY SNOW AND MVFR CEILINGS MAY BE OBSERVED AT GYY
THROUGH EARLY THIS MORNING.
- GUSTY NORTHWEST WINDS WILL CONTINUE THROUGH THE OVERNIGHT
HOURS BEFORE DIMINISHING.
- ANOTHER PERIOD OF SNOW IS EXPECTED THURSDAY NIGHT. IFR OR
LOWER VISIBILITIES WILL BE POSSIBLE DURING THE STEADIEST
SNOWFALL.
POOR QUALITY LAKE EFFECT SNOW SHOWERS AND ASSOCIATED MVFR
CEILINGS MAY CONTINUE TO AFFECT GYY AT TIMES THROUGH THE
OVERNIGHT HOURS. HOWEVER, THE MAIN LAKE EFFECT SNOW BAND AND
OVERALL WORSE CONDITIONS WILL REMAIN TO THE EAST OF GYY.
GYY WILL ALSO SEE THE STRONGEST NORTHWESTERLY WINDS TONIGHT,
WITH GUSTS NEAR AND IN EXCESS OF 30 KTS REMAINING POSSIBLE
THERE THROUGH THE EARLY OVERNIGHT HOURS. ELSEWHERE, EXPECT AT
LEAST OCCASIONAL NORTHWESTERLY GUSTS TO AROUND 25 KTS THROUGH
AROUND DAYBREAK BEFORE WINDS GRADUALLY DIMINISH THROUGH
TOMORROW MORNING AND EVENTUALLY FLIP TO A SOUTHWESTERLY
DIRECTION TOMORROW AFTERNOON.
OUR NEXT WEATHER SYSTEM WILL BEGIN TO MOVE INTO THE AREA
THURSDAY NIGHT, WITH SNOW EXPECTED TO BEGIN SOMETIME DURING THE
EARLY EVENING. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT ON
A THUMP OR TWO OF SNOW AFFECTING THE TERMINALS DURING THE
EVENING TIME FRAME, WITH A PERIOD OF IFR VISIBILITIES AND UP TO
A QUICK INCH OR TWO OF ACCUMULATION. AFTER THE MAIN PERIOD OF
STEADIER EVENING SNOWFALL, INTERMITTENT LOWER QUALITY SNOW
SHOWERS MAY PERSIST THROUGH THE REMAINDER OF THE NIGHT. MVFR
CEILINGS WILL ALSO LIKELY BE OBSERVED THURSDAY NIGHT, WITH A
PERIOD OF IFR CEILINGS NOT OUT OF THE QUESTION EITHER.
OGOREK
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...WINTER STORM WARNING UNTIL 9 AM CST THURSDAY FOR INZ002.
WINTER WEATHER ADVISORY UNTIL 9 AM CST THURSDAY FOR INZ011.
LM...GALE WARNING UNTIL MIDNIGHT CST TONIGHT FOR WINTHROP HARBOR IL
TO GARY IN.
SMALL CRAFT ADVISORY UNTIL 3 PM CST THURSDAY FOR WINTHROP
HARBOR IL TO GARY IN.
GALE WARNING UNTIL 3 AM CST THURSDAY FOR GARY TO BURNS HARBOR
IN-BURNS HARBOR TO MICHIGAN CITY IN.
VISIT US AT WEATHER.GOV/CHICAGO
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