969
FXUS63 KIWX 181719
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1219 PM EST SUN JAN 18 2026
KEY MESSAGES
- LIGHT SNOW SHOWERS CONTINUE TODAY. ADDITIONAL LIGHT SNOW
ACCUMULATIONS OF UP TO 1 INCH POSSIBLE.
- A DISTURBANCE MOVING THROUGH THIS EVENING INTO EARLY TUESDAY
MORNING BRINGS LAKE EFFECT SNOW ACCUMULATIONS OF 2 TO 6
INCHES MAINLY NORTH US-6 AND SYSTEM SNOW ACCUMULATIONS OF UP
TO AN INCH LATER THIS AFTERNOON THROUGH TONIGHT. HAZARDOUS
DRIVING CONDITIONS ARE POSSIBLE FROM LOW VISIBILITY DUE TO
SNOW AND GUSTY WINDS AS WELL AS SLICK ROADS. A WINTER WEATHER
ADVISORY HAS BEEN ISSUED FOR BERRIEN AND CASS COUNTIES IN
MICHIGAN FOR TONIGHT THROUGH MONDAY MORNING.
- SUBZERO SINGLE DIGIT WIND CHILLS EXPECTED TONIGHT, AND
DANGEROUSLY COLD WIND CHILLS OF 10 TO 20 BELOW SUNDAY NIGHT
AND MONDAY NIGHT.
DISCUSSION
ISSUED AT 345 AM EST SUN JAN 18 2026
THE ENERGY FROM THE UPPER LOW AND ITS ASSOCIATED AREA OF DEFORMATION
SLIDE EAST AWAY FROM THE AREA THIS MORNING AND THE LOWER LAKE MI
AREA DRIES OUT, TRAJECTORIES TURN MORE SOUTHWARD, AND INSTABILITY
DISSIPATES ALLOWING SNOW TO DISSIPATE AS WELL. SURFACE HIGH PRESSURE
AND SLIGHT MID LEVEL HEIGHT RISES ALLOW FOR A BREAK IN THE WINTRY
WEATHER UNTIL IT RETURNS AGAIN LATER THIS AFTERNOON. THIS TIME, A
CLIPPER SYSTEM AND ASSOCIATED VIGOROUS SHORTWAVE DIVES SOUTHEASTWARD
OUT OF CANADA TOWARD THE MID MISSISSIPPI VALLEY REGION BY THIS
EVENING. IT DOES LOOK LIKE THERE WILL BE A PERIOD OF SYSTEM SNOW IN
ADVANCE OF LAKE EFFECT SNOW ACCUMULATING LESS THAN 1" OF NEW SNOW
AWAY FROM LAKE MI ADJACENT LOCATIONS, BUT MORE LIKE 1 TO 2" IN
BERRIEN COUNTY WHERE LAKE ENHANCEMENT HELPS TO INCREASE TOTALS.
TRAJECTORIES REMAIN OUT OF THE SOUTHWEST UNTIL NOT TOO LONG AFTER
MIDNIGHT TONIGHT, WHEN MORE WEST-NORTHWESTERLY TRAJECTORIES 280-290
DEGREES TAKE OVER. DECENT LOW LEVEL MOISTURE AND WIND CONVERGENCE
PAIR WITH NEGATIVE THETA-E LAPSE RATES, INVERSION HEIGHTS AROUND
7500 TO 8500 FT, AND DELTA T VALUES BETWEEN 20 AND 25C TO EXCITE THE
LAKE EFFECT SNOW MACHINE. INVERSION HEIGHTS DROP TO MORE LIKE 4000
FT AROUND MIDDAY OR EARLY AFTERNOON MONDAY INDICATING THE INTENSITY
OF SNOW MAY WEAKEN SOME AND THE LOW LEVEL MOISTURE ALSO APPEARS TO
DRY OUT TO SOME EXTENT DURING THE AFTERNOON EVEN AS THE SNOW
LINGERS. LIGHT SNOW LIKELY CONTINUES DOWNWIND OF LAKE MI MONDAY
NIGHT AND INTO MIDDAY TUESDAY WHEN SOUTHERLY TRAJECTORIES TAKE OVER,
LOW LEVEL MOISTURE DRIES OUT, AND THETA-E INSTABILITY DISSIPATES.
ALL TOLD, OVER 36 HOURS, HAVE 3 TO 6 INCHES OF SNOW MAINLY NORTH OF
US-6, BUT ESPECIALLY IN BERRIEN AND CASS, MI COUNTIES. THE OTHER
FACTOR IN THE HAZARDS WITH THIS SNOW EVENT IS THE GUSTY WINDS, WHICH
LOOK TO BLOW AT BETWEEN 25 AND 35 MPH IN OUR SOUTHERN LOWER MI
COUNTIES UNTIL LATER MONDAY AFTERNOON. THIS WOULD CAUSE LOWERED
VISIBILITY FROM BLOWING SNOW WITH IT GETTING RIPPED APART AS WELL AS
FROM WHAT THE FALLING SNOW WOULD DO ON ITS OWN AND CAN CAUSE
DRIFTING OF SNOW ON N-S ROADS WITH THIS FINE DRY SNOW CONSISTENCY.
ONE ISSUE WITH THE SNOW RATIOS THAT COULD HAPPEN IS THAT THE DGZ AND
OMEGA ARE BELOW THE BEST SATURATION AREA MEANING THE SNOW RATIO
COULD BE LOWER (ALTHOUGH THE BEH LOCATION COULD HAVE MODELED MARINE
INFLUENCE MEANING IT COULD BE MODELED TOO WARM). DUE TO THESE
CONDITIONS, A WINTER WEATHER ADVISORY HAS BEEN ISSUED FOR
BERRIEN AND CASS COUNTIES IN MICHIGAN FOR THE TIME FRAME WHERE
THE MOST HAZARDOUS CONDITIONS ARE EXPECTED TONIGHT THROUGH
MONDAY MORNING.
THE OTHER HAZARD MOVING IN MONDAY IS THE COLD AIR. 850 MB
TEMPERATURES DROP INTO THE -20S CELSIUS AND THIS COLD AIR PAIRED
WITH THE GUSTY WINDS ALLOWS COLD WIND CHILLS TO REACH -10 TO -15F.
IT MAY ARRIVE TOO LATE MONDAY MORNING TO GET COLD WEATHER ADVISORY
CRITERIA AND HAVE DIURNAL HEATING AND LAKE CLOUDS INFLUENCING FINAL
TEMPERATURES. HOWEVER, TUESDAY HAS MUCH LOWER WINDS WITH THE LOW
PRESSURE AREA NOW FARTHER EAST OF THE AREA, BUT ALSO LOWER
TEMPERATURES SO THE MAX WIND AND MIN TEMPERATURES DON'T LINE UP
NICELY DURING THIS SCENARIO. WARM ADVECTION IS ALSO BEGINNING
TO ARRIVE TUESDAY MORNING SO THAT HIGHS, ESPECIALLY SOUTH OF
US-30, HAVE A GOOD CHANCE AT BEING 5 TO 10 DEGREES F WARMER.
THE WARM ADVECTION SIGNALS THE INFLUENCE OF OUR NEXT SYSTEM ALREADY,
FROM THE PLAINS, AND THERE'S STILL DIFFERENCES IN THE PLACEMENT OF
THE SURFACE LOW FOR LATE TUESDAY NIGHT/WEDNESDAY. POPS AND SNOW
AMOUNTS VARY BUT WILL CARRY THE NBM POPS TO INDICATE THE CHANCE FOR
SOME PRECIPITATION DURING THIS MIDWEEK TIME PERIOD.
STILL ANOTHER CLIPPER SYSTEM DIVES DOWN FROM CANADA WEDNESDAY NIGHT
AND THURSDAY PROVIDING ANOTHER ALLOTMENT OF COLD AIR AND KEEPING THE
LAKE EFFECT SNOW GOING.
ANOTHER SYSTEM LOOKS TO DEVELOP FOR FRIDAY AND SATURDAY TIME PERIOD.
THE TRACK FOR THIS SYSTEM STILL NEEDS IRONING OUT AS IT COULD PASS
SOUTH OF THE AREA. EVEN IF IT DEVELOPS OVERHEAD, IT MAY WAIT UNTIL
IT'S PASSED THE AREA. HAVE ALLOWED THE NBM POPS TO CONTINUE FOR THIS
SYSTEM AS WELL.
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...NONE.
OH...NONE.
MI...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST
MONDAY FOR MIZ078-177-277.
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...ROLLER
AVIATION...AGD/COBB
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