348
FXUS63 KIWX 172333
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
633 PM EST SAT JAN 17 2026
KEY MESSAGES
- LAKE EFFECT SNOW SHOWERS INCREASE THIS EVENING ACROSS
SOUTHWEST LOWER MICHIGAN AND CONTINUE THROUGH EARLY SUNDAY
MORNING. LIGHT SNOW ACCUMULATIONS OF 1 TO 3 INCHES POSSIBLE.
- SUBZERO SINGLE DIGIT WIND CHILLS EXPECTED TONIGHT, AND
DANGEROUSLY COLD WIND CHILLS OF 10 TO 20 BELOW SUNDAY NIGHT
AND MONDAY NIGHT.
- ANOTHER SYSTEM BRINGS SOME LIGHT SYSTEM SNOW TO THE AREA ALONG
WITH A PROLONGED PERIOD OF LAKE EFFECT SNOW SHOWERS MAINLY
ALONG AND NORTH OF THE TOLL ROAD. MODERATE SNOW ACCUMULATIONS
ARE LIKELY FROM SUNDAY EVENING THROUGH EARLY TUESDAY MORNING
FOR SOUTHWEST LOWER MICHIGAN.
DISCUSSION
ISSUED AT 244 PM EST SAT JAN 17 2026
A COMPLEX UPPER LEVEL WAVE PATTERN CONTINUES ACROSS CENTRAL CONUS
THIS AFTERNOON WITH A LARGE SCALE TROUGH EXTENDING FROM THE
CENTRAL/NORTHERN PLAINS INTO THE EASTERN GREAT LAKES. MEANWHILE, AN
UPPER LOW LEVEL IS BEGINNING TO SHIFT EAST-SOUTHEAST ACROSS THE QUAD
CITIES VICINITY. SOME DRIER MID LEVEL AIR ADVECTED INTO THE LOCAL
AREA THIS MORNING WHICH HAS SIGNIFICANTLY REDUCED MOISTURE DEPTHS.
THIS LIMITED MOISTURE WILL LIMIT ANY PRECIP FOR REMAINDER OF THE
AFTERNOON TO SOME PATCHY FLURRIES, PARTICULARLY SOUTHEAST THIRD OF
THE AREA WHICH IS IN CLOSER PROXIMITY TO SHEARED VORT MAX ASSOCIATED
THE STRONGER UPPER LEVEL JET WITH THE LARGER SCALE TROUGH. THE MORE
FAVORABLE AND DEEPER MOISTURE SUPPORTING MORE IMPACTFUL SNOWFALL
THIS AFTERNOON HAS PERSISTED TO THE NORTH OF THE QUAD CITIES
UPPER LOW FROM CENTRAL IOWA INTO EAST CENTRAL WISCONSIN. AS THIS
UPPER LOW SHIFTS EAST TONIGHT OVER CENTRAL INDIANA, THE
DEFORMATION ZONE OF THIS SYSTEM WILL SINK SOUTHEAST ALONG WITH
SOME MID LEVEL MOISTURE RECOVERY THAT SHOULD SUPPORT SOME
SCATTERED SNOW SHOWERS/FLURRIES MOVING INTO NW IN/SW LOWER
MICHIGAN. THIS EVOLUTION WILL ALSO SET THE STAGE FOR RENEWED
LAKE EFFECT SNOW SHOWERS PARTICULARLY ACROSS BERRIEN/CASS
COUNTIES MI WHERE WEST/SOUTHWEST FLOW TRAJECTORIES WILL BE MORE
FAVORABLE.
LAKE EFFECT PARAMETERS ARE NOT OVERLY FAVORABLE TONIGHT GIVEN
FAIRLY SHALLOW BASED INVERSION, LIMITED FETCH, AND SOME DRYING
OF UPPER PORTIONS OF DGZ TOWARD SUNDAY MORNING. AN INCH OR TWO
SEEMS POSSIBLE ACROSS SOUTHWEST LOWER MICHIGAN, WITH SOME
SLIGHTLY HIGHER AMOUNTS A POSSIBILITY ACROSS NORTHERN BERRIEN
COUNTY GIVEN FETCH CONSIDERATIONS. SOME DRIFTING SNOW CONCERNS
ARE POSSIBLE ACROSS BERRIEN COUNTY AS MODIFIED FLOW OFF LAKE
MICHIGAN SHOULD PROVIDE SLIGHTLY WARMER CONDITIONS, BETTER
MIXING, AND GREATER LIKELIHOOD OF MAINTAINING SOME GUSTS TO 20
TO 25 MPH AT TIMES THROUGH THE OVERNIGHT. OTHERWISE TONIGHT, IT
WILL BE QUITE COLD ALTHOUGH TEMPERATURE DROPS WILL BE SOMEWHAT
MITIGATED BY MAINTENANCE OF SOME SOUTHERLY FLOW TONIGHT. MIN
WIND CHILLS EARLY SUNDAY MORNING ARE EXPECTED TO RANGE FROM 5
BELOW TO 5 ABOVE.
LOW LEVEL FLOW SHOULD TEND TO BACK BY MIDDAY SUNDAY IN RESPONSE TO
LOW LEVEL TROUGHING MOVING ACROSS THE MID MS VALLEY DOWNSTREAM
OF NEXT UPPER LEVEL SHORT WAVE. THIS WILL ALLOW FOR DIMINISHMENT
OF LAKE EFFECT SNOW SHOWERS, BUT WILL ALLOW FOR SOME MODEST
INCREASE IN MID LEVEL MIXING RATIOS DURING THE AFTERNOON. THIS
NEXT UPPER TROUGH PASSAGE WILL BRING BITTER COLD AIR INTO THE
REGION SUNDAY NIGHT INTO MONDAY, ALONG WITH A POTENTIAL OF A
BRIEF WINDOW OF LIGHT SYSTEM SNOW GIVEN THE DEEPER MOISTURE
PROFILES (SYSTEM SNOW GENERALLY AN INCH OR LESS). OF GREATER
SIGNIFICANCE WILL BE THE RENEWED LAKE EFFECT SNOW SHOWER
DEVELOPMENT. WESTERLY FETCH SETUP ONCE AGAIN COULD BRING SEVERAL
INCHES OF SNOW ACCUMULATION OVER A 36 HOUR PERIOD FROM SUNDAY
EVENING THROUGH EARLY TUESDAY MORNING GENERALLY ALONG AND NORTH
OF THE TOLL ROAD, WITH GREATEST AMOUNTS ACROSS SOUTHWEST LOWER
MICHIGAN. INVERSION HEIGHTS WILL BE MORE SUBSTANTIAL THAN
TONIGHT'S SETUP, WITH GUIDANCE PROGS SUGGESTING 6- 8K FOOT
INVERSION HEIGHTS. THIS SETUP DOES LOOK MORE PROLONGED GIVEN
TENDENCY FOR LOW LEVEL TROUGHING TO LAG BEHIND SYNOPTICALLY
INDUCED TROUGH DUE TO POTENTIAL COLLECTIVE RESPONSE FROM WARMER
GREAT LAKES. THIS ALSO COULD BE A SETUP WHERE THE MAGNITUDE OF
LOW LEVEL COLD AIR MASS MOVING INTO GREAT LAKES SETS UP QUITE A
LOW LEVEL THERMAL RIBBON BETWEEN WEST SIDE OF LAKE MICHIGAN AND
THE THERMALLY MODIFIED, WARMER EASTERN SHORELINE. SOMETIMES IN
THESE SETUPS FRICTIONAL CONVERGENCE IN WIND ALONG THE EASTERN
SHORELINE CAN INTERACT WITH THIS ENHANCED BAROCLINICITY TO
PROVIDE SOME LOW LEVEL FGEN BOOST BRIEFLY AND SOME STRONGER
BANDING DESPITE WESTERLY FETCH. OVERALL THIS STILL LOOKS TO BE
MOST LIKELY A PROLONGED ADVISORY SITUATION SUNDAY EVENING INTO
EARLY TUESDAY MORNING AT THIS FORECAST DISTANCE, BUT COMBINATION
OF SNOW/WIND/COLD COULD PROVIDE SOME MODERATE IMPACTS FOR
SOUTHWEST LOWER MICHIGAN THAT WILL NEED TO BE CONSIDERED.
FOR MOST, THE BIG STORY FOR LATE SUNDAY INTO TUESDAY WILL BE THE
DANGEROUS COLD CONDITIONS. AS THIS ARCTIC AIRMASS BEGINS TO MOVE IN
LATE SUNDAY NIGHT, THE COMBINATION OF GUSTY POST-FRONTAL WINDS AND
FALLING TEMPS COULD PRODUCE MIN WIND CHILLS NEAR ADVISORY CRITERIA.
MONDAY NIGHT WILL FEATURE WEAKER WINDS, BUT COLDER TEMPS NEAR 0 THAT
SHOULD PUSH WIND CHILLS MORE SOLIDLY INTO ADVISORY CRITERIA.
THE LATTER PORTIONS OF NEXT WEEK STILL LOOK TO BE POTENTIALLY ACTIVE
AS 490DM 500 MB LOW SINKS ACROSS SOUTHEAST CANADA WHILE LARGER SCALE
FLOW DEAMPLIFIES ACROSS CONUS. THIS PATTERN SHOULD SETUP STRONG
BAROCLINICITY ACROSS CENTRAL CONUS WITH A CONDUCIVE UPPER
PATTERN FOR SEVERAL UPSTREAM WAVES TO INTERACT WITH THIS STRONG
BAROCLINIC ZONE FOR ADDITIONAL PERIODS OF SNOW AND INTRUSIONS
OF COLDER AIR TO PROVIDE BELOW NORMAL TEMPS ON THE WHOLE FOR THE
LONG TERM PERIOD.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 628 PM EST SAT JAN 17 2026
MODEST CLIPPER IS SLOWLY PIVOTING THROUGH ILLINOIS AND APPEARS
ON TRACK TO CLIP SOUTH BEND WITHIN THE NEXT FEW HOURS. ITS FATE
AS FAR EAST AS FWA IS UNCERTAIN GIVEN A DRY AIR MASS. THE
CEILING EVOLUTION ON SUNDAY OFFERS UNCERTAINTY IN THAT MVFR
CEILINGS ARE FAVORED BEHIND THE DEPARTING CLIPPER FOLLOWED BY A
NARROW WINDOW OF IMPROVEMENT BEFORE THE NEXT CLIPPER ARRIVES,
BRINING REDUCED CEILINGS AND EVENTUALLY SNOW.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST MONDAY FOR LMZ043-046.
GALE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY EVENING FOR
LMZ043-046.
DISCUSSION...MARSILI
AVIATION...BROWN
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