122
FXUS63 KIWX 050009
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
709 PM EST WED FEB 4 2026
KEY MESSAGES
- LIGHT SNOW THURSDAY AFTERNOON WITH UP TO 0.5' OF ACCUMULATION
POSSIBLE.
- FREEZING DRIZZLE POSSIBLE THURSDAY NIGHT INTO EARLY FRIDAY
AHEAD OF ANOTHER ROUND OF SNOW. SNOW FRIDAY MORNING COULD
ACCUMULATE 1-2", ESPECIALLY EAST OF I-69.
- LAKE EFFECT MAY DEVELOP FRIDAY AFTERNOON THROUGH EARLY SATURDAY
DOWNWIND OF LAKE MICHIGAN.
- A BRIEF COLD SNAP SATURDAY WILL BE FOLLOWED BY A WARM UP INTO
EARLY TO MIDDLE OF NEXT WEEK.
DISCUSSION
ISSUED AT 239 PM EST WED FEB 4 2026
SURFACE HIGH PRESSURE IS KEEPING OUR AREA LOCKED UNDER A LOW LEVEL
STRATUS DECK TODAY WITH PERSISTENT NORTHERLY WINDS. AS CLOUDS
PERSIST TONIGHT, TEMPERATURES ONLY FALL FROM WHERE THEY ARE NOW IN
THE UPPER TEENS AND LOW 20S INTO THE LOW TEENS OVERNIGHT (AS OPPOSED
TO TANKING INTO THE SINGLE DIGITS AND EVEN BELOW ZERO UNDER CLEAR
SKIES LIKE WHAT HAS HAPPENED OVER THE PAST WEEK). WINDS OVERNIGHT
INTO THE DAY ON THURSDAY SHIFT TO BECOME SOUTHWESTERLY, USHERING IN
WAA AHEAD OF OUR NEXT CHANCES FOR PRECIPITATION.
SEVERAL OPPORTUNTIES FOR PRECIPITATION ARISE THURSDAY AFTERNOON
THROUGH FRIDAY. TWO 500MB SHORTWAVES SWEEP THROUGH THE UPPER
MIDWEST AND GREAT LAKES REGIONS DURING THIS TIMEFRAME. THE FIRST
COMES THROUGH THURSDAY AFTERNOON AND TEMPERATURES WILL BE COLD
ENOUGH (LOW TO MID 20S) TO SUPPORT PRECIPITATION FALLING AS
SNOW. THURSDAY NIGHT, SNOW AMOUNTS WILL BE UP TO 0.5" FOR THE
ENTIRE AREA. LIGHT SNOW WILL PERSIST THROUGH THURSDAY NIGHT,
THEN FREEZING DRIZZLE MAY DEVELOP IN BETWEEN THE LULL IN SNOW.
THE BEST POTENTIAL OF FREEZING DRIZZLE APPEARS TO BE LATE
THURSDAY NIGHT THROUGH EARLY FRIDAY MORNING, IN BETWEEN ROUNDS
OF SNOW AND ALONG THE LEADING EDGE OF THE SECOND ROUND. MODELS
ARE PICKING UP A GLAZE TO A FEW HUNDREDTHS OF ICE AT MOST. THE
SECOND ROUND OF SNOW MOVES THROUGH FRIDAY MORNING AND EARLY
AFTERNOON AS A CLIPPER SYSTEM COMES THROUGH WITH THE ASSOCIATED
SECOND 500MB SHORTWAVE. THIS ROUND WILL BE SLIGHTLY MORE POTENT,
WITH SNOW AMOUNTS AROUND 1" EXPECTED EAST OF I- 69. LOCALIZED
AMOUNTS UP TO 2" WILL BE POSSIBLE IN OUR FAR NORTHWEST CWA.
OVERALL, HAVE STAYED CONSISTENT WITH THE PREVIOUS SHIFT IN TERMS
OF SNOWFALL AND QPF. USED A BLEND OF THE PREVIOUS FORECAST WITH
THE WPC GUIDANCE FOR PRECIPITATION AND SLRS. HIGHS ON FRIDAY
WILL BE IN THE MID 30S, WHICH WILL BE THE FIRST DAY ABOVE
FREEZING IN TWO WEEKS! EVEN THOUGH HIGHS WILL ONLY BE ABOVE
FREEZING FOR A FEW HOURS DURING THE DAY, THIS WILL LIMIT THE
SNOWFALL ACCUMULATION EFFICIENCY.
WITH STRONG CAA AND NORTHERLY LOW-LEVEL WINDS BEHIND THE CLIPPER
SYSTEM, LAKE EFFECT SNOW MAY DEVELOP FOR NORTHWEST INDIANA AND
SOUTHWEST LOWER MICHIGAN FRIDAY AFTERNOON INTO EARLY SATURDAY. THE
NAM ESPECIALLY IS STARTING TO PICK UP ON THIS AT THE END OF THE 12Z
RUN. DESPITE THE SHORELINE OF SOUTHERN LAKE MICHIGAN BEING MOSTLY
ICE COVERED, THE OPEN WATERS ARE STILL UNFROZEN. WITH A NORTHERLY
FETCH OVER LAKE MICHIGAN (AND POSSIBLE LAKE SUPERIOR CONNECTION),
THIS IS A FAVORABLE SETUP FOR LAKE EFFECT. IT IS STILL TOO EARLY TO
DETERMINE EXACT AMOUNTS, BUT THE BEST CHANCES FOR LAKE EFFECT WILL
LIKELY BE WEST OF US-31. AN UPPER LEVEL RIDGE BUILDS ACROSS THE
CENTRAL CONUS OVER THE WEEKEND, WHICH WILL ALLOW FOR LAKE EFFECT TO
TAPER OFF SATURDAY AS SUBSIDENCE WORKS IN. TEMPERATURES WILL BE COLD
WITH LOWS IN THE SINGLE DIGITS FRIDAY NIGHT AND SATURDAY'S HIGHS
ONLY IN THE TEENS. ANOTHER CLIPPER SYSTEM IS POSSIBLE SUNDAY,
ALTHOUGH MODEL GUIDANCE VARIES ON TIMING AND TRACK. IT IS
POSSIBLE THIS CLIPPER GOES FURTHER NORTH AND MISSES OUR AREA
COMPLETELY.
INTO NEXT WEEK, A WARM UP AND POSSIBLE THAW IS ON THE WAY! WHILE IT
IS TOO EARLY TO KNOW JUST HOW MILD TEMPERATURES WILL GET, HIGHS WILL
LIKELY BE ABOVE FREEZING FOR SEVERAL DAYS. NBM GUIDANCE HAS HIGHS IN
THE MID TO UPPER 30S (WHICH IS JUST A FEW DEGREES ABOVE NORMAL).
ENSEMBLE GUIDANCE IS MUCH MORE SUPPRESSED THAN IT WAS JUST A
FEW DAYS AGO; ONLY FEW RUNS NOW SHOW TEMPERATURES AS MILD AS THE
UPPER 30S TO LOW 40S. LOW CHANCES FOR HIGHS NEAR 40 WILL BE
ALONG AND SOUTH OF US 24 NEXT TUESDAY AND WEDNESDAY, WITH HIGHER
LIKELIHOOD ACROSS CENTRAL INDIANA. WE LIKELY WON'T MAKE A
MULTI-DAY RUN OF WIDESPREAD HIGHS IN THE 40S.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1218 PM EST WED FEB 4 2026
A MOISTURE-STARVED UPPER LEVEL TROUGH WILL TRACK ACROSS THE
SOUTHERN GREAT LAKES AND OHIO RIVER VALLEY INTO THIS EVENING.
SOME INCREASE IN MID LEVEL SUBSIDENCE INTO THIS EVENING IN THE
WAKE OF THIS WAVE SHOULD TEND TO ERODE LOW LEVEL CLOUDS. THE
CHANCES OF MVFR CIGS IN THE 2-3K FT RANGE WILL PERSIST TONIGHT
HOWEVER AS BACKING LOW LEVEL WINDS IN RESPONSE TO LOW LEVEL
ANTICYCLONE SINKING SOUTH ACROSS THE MID MS RVR VALLEY COULD
ALLOW FOR EASTWARD ADVANCEMENT OF WEAK LAKE AGGREGATE TROUGH.
MOISTURE DEPTHS AND INVERSION HEIGHTS WILL BE LIMITED SO
CURRENTLY NOT EXPECTING THIS TO BE MORE THAN PATCHY LIGHT
SNOW/FLURRIES. WARM ADVECTION INCREASES LATE TONIGHT INTO
THURSDAY IN ADVANCE OF WEAK NORTHWEST FLOW SHORT WAVE.
CONFIDENCE IN PRECIPITATION IS LOW IN THIS WARM ADVECTION PHASE
DUE TO MOISTURE LIMITATIONS, BUT BEST CHANCES OF LIGHT SNOW
THURSDAY MORNING APPEARS TO BE AT KSBN. GIVEN MOISTURE
LIMITATIONS, CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE PRECIP AT
THIS TIME WITH THE 18Z TAFS.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 651 PM EST WED FEB 4 2026
PREDOMINANTLY MVFR TO VFR CONDITIONS AT THE TERMINALS THIS
PERIOD. ANOTHER TRICKY CLOUD FORECAST WITH A LOT OF THE GUIDANCE
MISSING THE BROAD CLOUD DECK WITH CEILINGS AROUND 2500 FT OVER
MUCH OF NORTHERN IN/WESTERN MI/IL. THERE IS A BIT OF CLEARING
GENERALLY ALONG AND EAST OF I 69, WITH THE 2500FT CEILINGS
BECOMING MORE SCATTERED, BUT I SUSPECT THAT THE CLOUDS WESTWARD
WILL SHIFT EAST WITH TIME. KFWA IS RIGHT ALONG THIS BOUNDARY-
STILL REPORTING BKN026 AS OF THIS TIME. THERE IS ANOTHER
CLEARING FURTHER WEST FROM WI DOWN THROUGH IA/WESTERN IL, WITH
THE BACK EDGE OF OUR CLOUD SHIELD SLOWLY ERODING NEAR CHICAGO.
FOR BOTH SITES, I HAVE A TEMPO TO 3500FT (THOUGH IT MAY BE MORE
OF A SCT025/SKC BRIEFLY) FOR THE NEXT FEW HOURS TO ACCOUNT FOR
THIS. THE FAIRLY QUICK MOVING CLOUD DECK ON THE BACKSIDE OF THE
WESTERN CLEARING MAY CATCH UP TO OUR SLOW MOVING TROUGH/CLOUD
DECK BEFORE WE CAN CLEAR TOO MUCH-WHICH WOULD FAVOR KEEPING THE
MVFR CEILINGS IN FOR A LONGER PERIOD. OBS ALONG THE LEADING EDGE
OF THAT CLOUD DECK ARE AROUND 4-6KFT, THEN DROP TO 1500-2000FT
OR SO IN THE THICK OF IT. AMONG THE GUIDANCE THAT IS CAPTURING
THE CURRENT SITUATION FAIRLY WELL, ITS POSSIBLE WE DROP TO
AROUND 1500-2000 FT WITH THE SUBSIDENCE INVERSION OVERNIGHT
(KSBN) INTO THURSDAY MORNING (KFWA)-ESPECIALLY IF THE CLEARING
IS SHORT LIVED. THERE COULD BE SOME FLURRIES AT KSBN AS WAA
ARRIVES TOWARDS MORNING BUT DIDN'T HAVE ENOUGH CONFIDENCE TO ADD
TO THE TAF. BEYOND THAT, WE'LL SEE A PERIOD OF VFR CONDITIONS
BEFORE DROPPING BACK TO MVFR AFTER 19Z AT BOTH SITES-WITH THE
BEST CHANCE FOR SNOW AT KSBN AFTER THAT. KFWA MAY SEE SOME
TOWARDS THE END OF THE PERIOD, BUT CONFIDENCE IS GREATER AFTER
00Z.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...JOHNSON
AVIATION...MCD
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