609
FXUS63 KIWX 182058
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
358 PM EST SUN JAN 18 2026
KEY MESSAGES
- SYSTEM SNOW TONIGHT WILL BE FOLLOWED BY A PROLONGED PERIOD OF
LAKE EFFECT SNOW FROM LATE TONIGHT THROUGH MONDAY NIGHT.
SYSTEM SNOW ACCUMULATIONS SHOULD TOTAL AN INCH OR LESS WITH
ACCUMULATIONS OF 2 TO 6 INCHES NORTH OF THE TOLL ROAD FOR
FAVORED LAKE EFFECT AREAS FROM NW INDIANA INTO S LOWER
MICHIGAN.
- DANGEROUS WIND CHILLS AROUND 15 BELOW ZERO EXPECTED LATE
TONIGHT THROUGH EARLY TUESDAY.
- ANOTHER FAST MOVING SYSTEM WILL BRING SOME LIGHT SNOW
ACCUMULATIONS TUESDAY NIGHT INTO EARLY WEDNESDAY, ESPECIALLY
ALONG AND NORTH OF US ROUTE 30.
- TEMPERATURES MODERATE BACK INTO THE LOWER 30S BRIEFLY
WEDNESDAY, BUT TEMPERATURES TURN COLDER ONCE AGAIN FOR LATTER
PORTIONS OF WORK WEEK INTO NEXT WEEKEND.
DISCUSSION
ISSUED AT 357 PM EST SUN JAN 18 2026
NO MAJOR CHANGES TO PREVIOUS FORECAST. CONFIDENCE CONTINUES TO
INCREASE IN IMPACTS DUE TO THE COMBINATION OF SNOW AND BLOWING SNOW,
PARTICULARLY ALONG AND NORTH OF THE TOLL ROAD DOWNWIND OF LAKE
MICHIGAN. A COLD WEATHER ADVISORY HAS ALSO BEEN ISSUED FOR NORTHERN
INDIANA AND NORTHWEST OHIO FOR MONDAY THROUGH EARLY TUESDAY.
SEVERAL UPSTREAM SHORT WAVES SPILLING DOWN WESTERN CONUS UPPER RIDGE
WILL BRING A REINFORCING ARCTIC AIRMASS INTO THE REGION LATER
TONIGHT INTO MONDAY. A LEAD WEAKER SHORT WAVE MOVING IN FROM THE
WESTERN GREAT LAKES HAS COMBINED WITH SOME SHALLOW BASED INSTABILITY
FOR SOME SPORADIC LIGHT SNOW SHOWERS FLURRIES/THIS AFTERNOON. THIS
HAS BEEN A STEADY LIGHT SNOW BUT NOT AT A RATE SUFFICIENT FOR
ANY ACCUMULATION.
SNOW IS EXPECTED TO OVERSPREAD THE AREA THIS EVENING IN RESPONSE TO
WESTERN GREAT LAKES SHORT WAVE AND SOME WEAK ASSOCIATED WARM
ADVECTION. A PAIR OF SHORT WAVES WILL THEN DROP SOUTHEAST LATE
EVENING INTO EARLY MONDAY MORNING WITH A STRONG LOW LEVEL FRONT
SWEEPING ACROSS THE SOUTHERN GREAT LAKES. THIS WILL LEAD TO
INCREASING LAKE INDUCED INSTABILITY DEPTHS ALONG WITH AN ENHANCEMENT
TO SOME LIGHT SYNOPTICALLY-FORCED SNOW AS THIS STRONGER VORT MAX
MOVES THROUGH. CURRENT THINKING IS THAT INITIALLY THE MORE IMPACTFUL
LAKE EFFECT OVERNIGHT WILL BE CLOSER TO THE LAKE MICHIGAN SHORELINE
AS ASSOCIATED LOW LEVEL TROUGH SWEEPS ACROSS THE SOUTHERN GREAT
LAKES. THERE IS SOME CONCERN THAT STRONG COLD ADVECTION IN THIS
PATTERN AND MODIFICATION OF LOW LEVEL AIRMASS IN THIS WESTERLY FLOW
REGIME COULD LEAD TO WINDOW OF SOME ENHANCED BANDING ACROSS
SOUTHWEST LOWER MICHIGAN IN VICINITY OF THIS TROUGH AXIS AS
CONVERGENCE IS ENHANCED NEAR THIS TROUGH. CONVERGENCE ALONG THIS
TROUGH MAY ALSO BE ENHANCED BY FRICTIONAL EFFECTS FROM LAKE
MICHIGAN.
INSTABILITY DEPTHS WILL CONTINUE TO BUILD INTO EARLY MONDAY MORNING
WITH MULTIBAND SETUP EXPECTED, ESPECIALLY ALONG AND NORTH OF THE
TOLL ROAD. GREATEST ACCUMULATIONS IN THE 3 TO 6 INCH RANGE ARE STILL
EXPECTED ACROSS BERRIEN/POSSIBLY NORTHERN CASS COUNTIES MI, WITH
LESSER AMOUNTS OF 2 TO 4 INCHES NORTH OF THE TOLL ROAD IN FAVORED N
INDIANA LAKE EFFECT AREAS. SOME OF THESE MODERATE ACCUMULATIONS
COULD EXTEND INTO ST JOSEPH CO MICHIGAN, BUT CONFIDENCE IS SLIGHTLY
LOWER. WITH DEEP MIXED LAYER IN STRONG COLD ADVECTION, WIND GUSTS IN
THE 30 TO 35 MPH RANGE STILL APPEAR LIKELY ON MONDAY WITH 850 MB
WINDS ON THE ORDER OF 35 KNOTS. GIVEN DRY NATURE OF THIS SNOW,
CONFIDENCE CONTINUES TO INCREASE IN IMPACTS DUE TO THE COMBINATION
OF THIS DRIER SNOW AND STRONG WIND GUSTS. HAVE EXPANDED THE WINTER
WEATHER ADVISORY TO NORTHERN LAPORTE, ST. JOSEPH IN, AND ELKHART
COUNTIES ALONG WITH ST. JOSEPH MI COUNTY (GREATEST IMPACTS EXPECTED
NORTH OF TOLL ROAD). SOME CONSIDERATION WAS GIVEN TO UPGRADING
BERRIEN COUNTY TO A WARNING GIVEN COMBINATION SNOW/STRONG WINDS BUT
HAVE HELD OFF AT THIS TIME. IF A MORE ORGANIZED BAND CAN FORM IN THE
EARLY STAGES OF THIS EVENT OVERNIGHT/EARLY MONDAY ACROSS SW LOWER
MICHIGAN, SOME LOCALLY HIGHER AMOUNTS IN EXCESS OF 6 INCHES WOULD BE
POSSIBLE THAT COULD YIELD MORE OF A WARNING LEVEL IMPACT WHEN PAIRED
WITH THE STRONG WIND GUSTS. CONFIDENCE IN ANYTHING MORE THAN AN INCH
OR TWO IS LOWER ACROSS BRANCH/HILLSDALE, ALTHOUGH THESE AREAS DID
EXPERIENCE SLIGHTLY MORE SNOW A FEW DAYS AGO. THIS GREATER PRE-
EXISTING SNOW DEPTH COULD LEAD TO SOME BLOWING/DRIFTING WHEN
COMBINED WITH NEW SNOWFALL, BUT CONFIDENCE WAS NOT HIGH ENOUGH TO
EXPAND ADVISORY INTO THESE COUNTIES. LAKE EFFECT SNOW SHOWERS WILL
LIKELY PERSIST INTO MONDAY EVENING AS INSTABILITY DEPTHS GRADUALLY
DIMINISH. WINDS ALSO SHOULD BE ON THE DOWNWARD TREND WITH LESSENING
BLOWING/DRIFTING CONCERNS HEADING INTO MID-LATE EVENING.
THE OTHER CONCERN WITH THIS SYSTEM WILL BE THE INFLUX OF MUCH COLDER
AIR AND POTENTIAL OF REACHING COLD WEATHER ADVISORY CRITERIA.
TEMPS SHOULD DROP SHARPLY TO THE SINGLE DIGITS ABOVE ZERO MONDAY
MORNING ACROSS NORTHERN INDIANA, AND WHEN COMBINED WITH
MAGNITUDE OF THE STRONG POST-FRONTAL WINDS SHOULD LEAD TO WIND
CHILLS AROUND 15 BELOW AT TIMES MONDAY MORNING INTO EARLY
AFTERNOON. WITH CONTINUED COLD ADVECTION AND LOW LEVEL COLD CORE
SHIFTING ACROSS LOCAL AREA DURING AFTERNOON, WIND CHILLS WILL
LIKELY NOT EXHIBIT MUCH OF ANY DIURNAL IMPROVEMENT. A COLD
WEATHER ADVISORY HAS BEEN ISSUED FOR ALL OF IN/OH PORTION OF
FORECAST AREA MONDAY THROUGH EARLY TUESDAY MORNING, WITH A LATER
ONSET TIME MONDAY AFTERNOON ACROSS NW OHIO.
SOME LAKE EFFECT SNOW SHOWERS COULD PERSIST INTO EARLY TUESDAY
BUT OTHERWISE ANOTHER VERY COLD DAY TUESDAY WITH ATTENTION
TURNING TO NEXT FAST MOVING UPSTREAM SYSTEM. WHILE NOT AN OVERLY
IMPRESSIVE DYNAMIC WAVE, THIS DISTURBANCE WILL HAVE A VERY
STRONG LOW LEVEL BAROCLINIC ZONE TO WORK WITH AND SHOULD
PRODUCE ADDITIONAL SNOW ACCUMULATIONS WITH WAA/FGEN FORCING
LATER TUESDAY NIGHT INTO EARLY WEDNESDAY.
BRIEFLY WARMER CONDITIONS ARE EXPECTED FOR WEDNESDAY BUT MEDIUM
RANGE MODELS ARE IN DECENT AGREEMENT THROUGH LATE WORK WEEK ON
REINFORCING PUSH OF MUCH BELOW NORMAL TEMPERATURES BACK INTO THE
REGION WITH RENEWED LAKE EFFECT POTENTIAL. MEDIUM RANGE GUIDANCE
BEGINS TO DIVERGE A BIT NEXT WEEKEND WITH LARGE RUN TO RUN
VARIABILITY IN POTENTIAL OF LARGER SCALE SYSTEM NEXT WEEKEND.
OVERALL TREND IN LATEST 12Z SUITE SUPPORTS MORE OF A SUPPRESSED
SOLUTION WELL TO THE SOUTH DUE TO STRENGTH OF 1040-1045 MB HIGH.
BLENDED POPS MAINTAIN JUST SOME LOW TO MID RANGE CHANCE POPS
FOR NEXT WEEKEND, AND SEE NO REASON TO DEVIATE AT THIS TIME
GIVEN MODEL VOLATILITY AT THIS FORECAST DISTANCE. CONFIDENCE
REMAINS HIGHER IN MUCH BELOW NORMAL TEMPS CONTINUING THROUGH
NEXT WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1215 PM EST SUN JAN 18 2026
WEAK SHORTWAVE WILL CONTINUE TO SUPPORT SOME MVFR STRATUS AND
FLURRIES. A MUCH STRONGER, SYSTEM ARRIVES TONIGHT WITH ANOTHER
ROUND OF LIGHT SNOW. IFR VISIBILITIES STILL APPEAR LIKELY,
PARTICULARLY AT KSBN GIVEN LAKE CONTRIBUTION. INCREASED WEST-
SOUTHWEST WINDS WILL ALSO CAUSE BLOWING SNOW, ESPECIALLY ON
MONDAY.
IWX WATCHES/WARNINGS/ADVISORIES
IN...WINTER WEATHER ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING
TO 7 PM EST /6 PM CST/ MONDAY FOR INZ005-103-104-204.
COLD WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ MONDAY TO 9 AM
EST /8 AM CST/ TUESDAY FOR INZ005>009-012>015-017-018-020-
022>027-032>034-103-104-116-203-204-216.
OH...COLD WEATHER ADVISORY FROM 1 PM MONDAY TO 9 AM EST TUESDAY FOR
OHZ001-002-004-005-015-016-024-025.
MI...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 1 AM EST
TUESDAY FOR MIZ078-079-177-277.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST MONDAY FOR LMZ043-046.
GALE WARNING FROM 1 AM TO 4 PM EST MONDAY FOR LMZ043-046.
HEAVY FREEZING SPRAY WARNING FROM 1 AM MONDAY TO 7 AM EST
TUESDAY FOR LMZ043-046.
DISCUSSION...MARSILI
AVIATION...COBB
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