368
FXUS63 KIWX 202346
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
646 PM EST TUE JAN 20 2026
KEY MESSAGES
- LIGHT SNOW ACCUMULATIONS ARE EXPECTED LATE TUESDAY NIGHT INTO
WEDNESDAY MORNING. THERE IS A 30 TO 50 PERCENT PROBABILITY OF
GREATER THAN 3 INCHES OF SNOW ACCUMULATION ACROSS PRIMARILY
OUR MICHIGAN COUNTIES.
- AFTER A BRIEF WARM-UP ON WEDNESDAY, A BITTERLY COLD ARCTIC AIR
MASS IS POISED TO RETURN LATER THIS WEEK THROUGH THE WEEKEND.
THERE IS A HIGH PROBABILITY (GREATER THAN 80%) THAT DAYTIME
HIGHS ON FRIDAY AND SATURDAY WILL REMAIN IN THE SINGLE DIGITS.
SOME AREAS MAY STRUGGLE TO GET ABOVE ZERO.
- THERE WILL BE PERIODIC CHANCES OF LAKE EFFECT SNOW SHOWERS
FROM WEDNESDAY NIGHT THROUGH THE WEEKEND.
DISCUSSION
ISSUED AT 209 PM EST TUE JAN 20 2026
THE INHERITED FORECAST REMAINS ON TRACK FOR THE AFTERNOON FORECAST
PACKAGE W/ MID-LEVEL HEIGHT RISES CONTRIBUTING TO A RELATIVE LULL IN
PRECIPITATION AS TEMPERATURES REBOUND INTO THE TEENS. THE MAIN FOCUS
IN THE NEAR TERM CONTINUES TO BE SNOW CHANCES FOR TONIGHT W/ THE
NEXT CLIPPER SYSTEM. IT DOES SEEM THE TRAJECTORY OF THE MID-LEVEL
MOISTURE PLUME HAS TRENDED SLIGHTLY NORTHWARD, WITH THE MAIN FOCUS
AREA CUTTING OFF ON THE VERY NORTHERN FRINGE OF OUR CWA. HIGH-RES
GUIDANCE STILL SUGGESTS DECENT PROBABILITIES OF 2-4 INCHES ACROSS
THE NORTHERN HALF OF BERRIEN, CASS, AND ST JOSEPH (MI), SO HAVE
OPTED FOR A WINTER WEATHER ADVISORY FOR OUR MICHIGAN COUNTIES W/
THIS FORECAST PACKAGE. ELSEWHERE, SNOWFALL ACCUMULATIONS SHOULD
GENERALLY BE LESS THAN ONE INCH. EXPECT SNOW CHANCES TO DIMINISH
QUICKLY HEADING INTO THE AFTERNOON ON WEDNESDAY. CONCERNING THE
UPCOMING COLD SNAP, GEFS PLUMES SUGGEST H85 TEMPERATURES BOTTOMING
OUT AROUND 12Z FRIDAY W/ 25TH %ILES AROUND -27 C. EFI VALUES FOR
TMIN TREND LOWER HEADING INTO THE FIRST HALF OF THE WEEKEND WITH SOT
VALUES APPROACHING 1, SO TEND TO LEAN MORE TOWARD THOSE COLDER H85
TEMPERATURES WHICH COULD SUPPORT DAYTIME HIGHS ON FRIDAY STRUGGLING
TO GET MUCH WARMER THAN +5 F, IF THAT, WITH LOWS LIKELY BELOW ZERO.
COLD WEATHER HEADLINES WILL LIKELY BE NECESSARY OVER THE COURSE OF
THE NEXT FEW DAYS. /HAMMER
PREVIOUS DISCUSSION:
HEIGHT RISES AND MID LEVEL RIDGING ALLOW FOR SUPPRESSION OF
WIDESPREAD PRECIPITATION EVEN FOR THE LAKE BELT FROM LATER TODAY
INTO TONIGHT. HOWEVER, A CLIPPER SYSTEM ALREADY INTRODUCES SNOW
CHANCES TO THE AREA LATER TUESDAY NIGHT AND THAT CONTINUES
WEDNESDAY. THIS IS WHEN THE BETTER MOISTURE PLUME ARRIVES, AND THIS
ONE HAS A CONNECTION TO THE GULF. AS SUCH, IT LOOKS LIKE 3 TO 6
INCHES OF SNOW IS MOST POSSIBLE NORTH OF THE TOLL ROAD LATE TUESDAY
NIGHT INTO WEDNESDAY. ENERGETIC LAPSE RATES AND A DEPARTING LOW
PRESSURE SYSTEM ALLOW FOR A CHANCE FOR GUSTY WINDS 30 TO 40 MPH
ESPECIALLY IN THE I-69 CORRIDOR IN THE MORNING.
WHAT MAY BE A BRIEF BREAK IN THE WEATHER WEDNESDAY AFTERNOON AND
EVENING QUICKLY REVERTS BACK TO PRECIPITATION AS A LITTLE DRIER
CLIPPER PUSHES THROUGH WEDNESDAY NIGHT. THIS ONE SHOWS SIGNS OF A
MOISTURE PLUME, BUT IT DOESN'T APPEAR TO HAVE A GULF CONNECTION LIKE
THE PREVIOUS ONE DOES. THE NAM APPEARS TO HAVE SOME SBCAPE AND
EXCITED SNOW SQUALL PARAMETER INCLUDING SOME ENERGETIC LOW LEVEL
LAPSE RATES THAT CONTINUE INTO THE OVERNIGHT HOURS.
THE SHEARED AREA OF VORTICITY BEHIND THE AFOREMENTIONED CLIPPER
SYSTEM REMAINS NEAR THE TEAR DROP OF LAKE MI WITH TIMES OF CAA
THROUGH THE AREA ALLOWING FOR TIMES OF LAKE ENHANCEMENT BETWEEN
WEDNESDAY EVENING AND THURSDAY EVENING. ON THE WHOLE, THESE CHANCES
LOOK TO BE WEAK AND LIGHT, BUT THE THE THURSDAY NIGHT AND FRIDAY
LAKE ENHANCED PROFILES APPEAR MORE RESPECTABLE.
FOR THURSDAY NIGHT, A VORT MAX ROUNDS THE BASE OF THE TROUGH AND
PUSHES ANOTHER DRY CLIPPER SYSTEM THROUGH THE AREA. THIS LOOKS TO
AFFECT TRAJECTORIES ACROSS LAKE MI AND LIKELY KEEPS THE LAKE
ENHANCEMENT GOING INTO THE WEEKEND. THE OTHER STORY IS THE MUCH
COLDER AIR ARRIVING FRIDAY MORNING WITH -25 TO -30C 850 MB TEMPS
MOVING ACROSS THE AREA. THE GOOD THING THIS TIME IS THAT WITH THE
ARRIVAL OF THE STRONG 1050 MB HIGH PRESSURE SYSTEM, THE AIR WILL BE
COLD, BUT THE WINDS WILL BE MORE RELAXED THAN OUR RECENT COLD
AIRMASS DEPARTING. HIGHS FRIDAY AND SATURDAY STRUGGLE TO GET INTO
THE TEENS AND LOWS FRIDAY NIGHT THROUGH SUNDAY NIGHT ARE IN THE
SINGLE DIGITS ABOVE AND BELOW ZERO. THIS WOULD MAKE COLD WIND
ADVISORY THRESHOLD WIND CHILLS POSSIBLE AGAIN OVERNIGHT. /ROLLER
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 631 PM EST TUE JAN 20 2026
VFR CONDITIONS GIVE WAY TO DETERIORATING CONDITIONS AS A
CLIPPER SYSTEM MOVES THROUGH. BROAD SURFACE LOW IS OVER NEBRASKA
WITH A WARM FRONT EXTENDING EAST, BISECTING THE SOUTHERN-THIRD
OF IL. THERE IS MEDIUM CONFIDENCE ON THE START TIME FOR SNOW AS
LOW- LEVEL DRY AIR AND RELATIVELY MODEST FORCING DECREASES
CONFIDENCE. THE LOW-LEVEL JET RAMPS UP TO ABOUT 40-45 KNOTS
AFTER 09Z, BUT DURATION IS SOMEWHAT SHORT AND A LACK OF
INVERSION SUGGESTS TURBULENCE IN LIEU OF LLWS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...WINTER WEATHER ADVISORY FROM 1 AM TO 10 AM EST WEDNESDAY FOR
MIZ078>081-177-277.
MARINE...NONE.
DISCUSSION...HAMMER
AVIATION...BROWN
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