747
FXUS63 KIWX 020802
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
302 AM EST MON FEB 2 2026
KEY MESSAGES
- A SYSTEM MOVES THROUGH PROVIDING LESS THAN 1 INCH OF NEW SNOW
TO THE AREA. SOME FREEZING DRIZZLE MAY MIX IN SPOTS WITH A
LIGHT GLAZE POSSIBLE.
- A SYSTEM MAY BRING LIGHT SNOW TO AREAS SOUTH OF US-30 TONIGHT
INTO TUESDAY.
- NOT QUITE AS COLD THIS WEEK WITH HIGHS IN THE 20S AND LOWS IN
THE TEENS TO SINGLE-DIGITS.
DISCUSSION
ISSUED AT 258 AM EST MON FEB 2 2026
AN 850 MB THETA-E PLUME PAIRED WITH AN AREA OF WAA TRAVERSES THE
AREA TODAY AS A LOW PRESSURE FORMS TO THE NORTH OF THE GREAT LAKES
AND PUSHES AN OCCLUDED FRONT THROUGH. INITIAL REPORTS OUT OF IL
INDICATE AREAS OF FREEZING DRIZZLE MIXING IN WITH SNOW AND THE
MODELS BEAR THIS OUT AS DGZ SATURATION APPEARS TO STRUGGLE,
ESPECIALLY ON THE BACK END OF THE FRONTAL PASSAGE. THE MAIN AREA OF
OMEGA PUSHES THROUGH BETWEEN 9 AND 18Z AND MOST OF THAT APPEARS TO
RESIDE WITHIN THE DGZ, WHICH IS SATURATED, AT LEAST THE BOTTOM PART
OF IT IS AND THAT MAY LOWER SLR. DGZ SATURATION ALREADY APPEARS TO
DROP OFF AROUND 12Z IN WESTERN AREAS AS THE BACKSIDE OF THE MOISTURE
PLUME BEGINS TO MOVE THROUGH FROM WEST TO EAST. A THIN AREA OF LOW
LEVEL MOISTURE REMAINS IN THE LOW LEVELS RESEMBLING STRATUS AND IT
IS QUESTIONABLE IF THERE'S ENOUGH LIFT TO FORCE FREEZING DRIZZLE,
HALTING PRECIPITATION INSTEAD. HOWEVER, THE BACKSIDE OF THE FRONT
APPEARS TO BE THE BEST CHANCE FOR THE FREEZING DRIZZLE, IF IT
OCCURS AT ALL.
BEHIND THIS FRONT, THE VORT MAX CAUSING THE SFC LOW OVER THE
NORTHERN GREAT LAKES DIVES SOUTHEAST AND BRINGS A SHORTWAVE EASTWARD
ALONG ITS SOUTHWESTERN PERIPHERY. THE NAM, DURING THIS TIME, HAS A
BOUNDARY MOVING SOUTHWARD THROUGH MI FROM 12Z TO 21Z TUESDAY.
INVERSION HEIGHTS FROM LAKE ENHANCEMENT APPEAR TO BE MARGINAL AT
ONLY 3 TO 4 KFT AND DELTA TS ARE ONLY 10C. MEANWHILE, THETA-E
INSTABILITY IS ALSO MARGINAL AND THE MOISTURE COLUMN LEAVES A LOT
TO BE DESIRED.
AWAY FROM LAKE MI, THE AFOREMENTIONED SHORTWAVE ALONG THE UPPER
LOW'S PERIPHERY FORCES A LOW PRESSURE SYSTEM THAT, BY TUESDAY,
PHASED LOW PRESSURE IN THE TENNESSEE RIVER VALLEY CREATES A PRECIP
SHIELD THAT COULD GRAZE OUR SOUTHERN TIER OF COUNTIES. MODEL
CERTAINTY HAS ABOUT A 20 PERCENT CHANCE AT 0.5 INCH OR GREATER
SNOWFALL AND THERE IS NOT ONE MODEL THAT IS COMPLETELY DEVOID OF
SNOW ACROSS THE AREA (MANY HAVE 0.1 INCH OF SNOW). THE NAM IS
PRODUCING THE MOST SNOW AT 1 TO 3 INCHES ACROSS OUR SOUTHERN TIER OF
COUNTIES (WHITE TO JAY). THE NORTHERN PERIPHERY OF THE PRECIP SHIELD
IS KNOWN TO RUN INTO SATURATION PROBLEMS, BUT THAT'S USUALLY WHEN
THE SURFACE HIGH IS JUST TO THE NORTH OF THE LOW. THIS TIME THE
SURFACE HIGH IS TRAILING THE LOW, BACK IN THE NORTHERN PLAINS.
IT IS INTERESTING SEEING A GOOD AMOUNT OF MODELS CREATING WHAT
APPEARS TO BE LAKE EFFECT SNOW TUESDAY NIGHT INTO WEDNESDAY, BUT
THERE'S QUITE A BIT OF TYPICAL INGREDIENTS FOR LES THAT ARE MISSING.
TRAJECTORIES APPEAR TO BE MORE NORTHEASTERLY WITH MUCH MORE OF THE
LOW LEVEL MOISTURE JUST WEST OF THE AREA IN LOT'S AREA, WHICH IS
ALSO WHERE THE BETTER THETA-E INSTABILITY RESIDES. THAT IS UNTIL WE
GET TO AFTER 9Z WEDNESDAY AS TRAJECTORIES TAKE A MORE NORTHWESTERLY
DIRECTION. STILL THE THETA-E INSTABILITY IS NOT ALL THAT GREAT AS IT
MOVES ONSHORE DURING THE DAY WEDNESDAY. DELTA TS APPEAR TO BE AROUND
10 TO 15C AND INVERSION HEIGHTS ARE AROUND 4 KFT DURING THIS TIME.
WILL CONTINUE THE SLIGHT CHANCE MENTION, BUT IT DOES APPEAR TO BE
LIGHT SNOW IF IT DOES HAPPEN.
DRY WEATHER FOLLOWS FOR THURSDAY WITH SOME MID LEVEL RIDGING EVIDENT
AND SURFACE PRESSURE PASSING THROUGH.
WE'LL, THEN, HAVE TO WATCH THE THURSDAY NIGHT INTO FRIDAY PERIOD AS
ANOTHER CLIPPER SYSTEM DIVES DOWN THROUGH THE GREAT LAKES REGION.
THE COLD AIRMASS THAT MOVES THROUGH IN CONJUNCTION WITH THAT SYSTEM
IS MUCH COLDER ON THE GFS AND IS CLOSER IN LINED WITH WHAT WE JUST
GOT OUT OF WITH 850 MB TEMPERATURES AROUND -20C. THE AIRMASS BEHIND
THE CLIPPER IS WARMER AND MUCH MORE TRANSIENT ON THE ECMWF SO THAT
BY SUNDAY, WE'RE BACK INTO THE ABOVE FREEZING AIR AT 850 MB (NOT SO
ON THE GFS). IT DOES LOOK POSSIBLE TO SEE A PERIOD OF LES TAKE OVER
LATER FRIDAY INTO SATURDAY. WE ALSO APPROACH COLD WEATHER ADVISORY
WIND CHILLS SATURDAY MORNING AND SO THAT WILL HAVE TO WATCHED.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1253 AM EST MON FEB 2 2026
VFR CONDITIONS EXPECTED TO DETERIORATE TO MVFR/IFR IN CIGS/VSBYS AS
A CLIPPER SYSTEM CONTINUES TO MOVE INTO THE AREA. CURRENT RADAR
DOES SHOW LIGHT RETURNS CURRENTLY OVER THE WESTERN IN/EASTERN
IL BORDER AS OF 06Z MON. SOME UNCERTAINTY ON HOW QUICKLY THESE
INCOMING SNOW SHOWERS BEGIN TO REACH THE SURFACE WITH THE DRY
AIR CURRENTLY IN PLACE, HOWEVER BETWEEN 12-15Z MON THIS SHOULD
BEGIN TO HAPPEN WITH KSBN FIRST THEN KFWA AS THE DISTURBANCE
MOVES EASTWARD. VFR CONDITIONS SHOULD RETURN TO KSBN AFTER 01Z
TUE WHILE KFWA SHALL RETURN TO MVFR IN LOWERED CIGS THROUGH THE
REMAINDER OF THIS TAF PERIOD. WINDS OUT OF THE S-SW THIS
EVENING VEERING TOWARDS THE W-SW THROUGH THE PERIOD.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...ROLLER
AVIATION...ANDERSEN
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