896
FXUS63 KIWX 010912
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
412 AM EST MON DEC 1 2025
KEY MESSAGES
- PATCHY FOG CAN BE EXPECTED ACROSS PORTIONS OF THE AREA THIS
MORNING. THE FOG MAY BE LOCALLY DENSE EARLY MORNING.
- SNOW IS EXPECTED TO OVERSPREAD THE AREA LATE THIS AFTERNOON
AND TONIGHT. SNOW ACCUMULATIONS ARE EXPECTED TO RANGE FROM AN
INCH OR TWO ACROSS SOUTHERN LOWER MICHIGAN TO 2 TO 4 INCHES
ACROSS MUCH OF NORTHERN INDIANA AND NORTHWEST OHIO.
- SOME LINGERING LAKE EFFECT SNOW SHOWERS COULD PERSIST INTO TUESDAY
MORNING BUT ARE NOT EXPECTED TO BRING SIGNIFICANT ADDITIONAL
ACCUMULATIONS.
- ADDITIONAL SNOW CHANCES FOR MIDWEEK FOLLOWED BY MUCH COLDER
AIR.
DISCUSSION
ISSUED AT 406 AM EST MON DEC 1 2025
ANOTHER SYSTEM WILL BRING WIDESPREAD SNOW TO THE AREA TONIGHT, WITH
A TOTAL OF 1 TO 4 INCHES EXPECTED. A LOCALLY HIGHER AMOUNT IS
POSSIBLE ESPECIALLY ALONG AND SOUTH OF US ROUTE 24 CORRIDOR WHERE A
LOCALLY STRONGER BAND COULD SET UP. A WINTER WEATHER ADVISORY IS IN
EFFECT TONIGHT FOR NORTHERN INDIANA AND NORTHWEST OHIO.
LAKE EFFECT SNOW SHOWERS HAVE DIMINISHED EARLY THIS MORNING AS
INVERSION HEIGHTS HAVE LOWERED AND SNOW GROWTH REGION HAS DRIED OUT.
THERE COULD BE SOME LINGERING VERY LIGHT DRIZZLE OR FLURRIES ACROSS
FAR NW IN/SOUTHWEST LOWER MI THROUGH DAYBREAK, BUT NO ADDITIONAL
SNOW ACCUMULATION IS EXPECTED. THE OTHER NEAR TERM ISSUE HAS BEEN
SOME PATCHY DENSE FOG ACROSS THE AREA. RADIATIONAL COOLING OVER
WET/WARMER SNOWPACK HAS BEEN CONDUCIVE FOR SOME SHALLOW FOG,
LOCALLY DENSE. HAVE ISSUED AN SPS TO COVER THIS WITH LOW
CONFIDENCE THAT COVERAGE WILL WARRANT HEADLINES AT THIS TIME.
THE BUSY WEATHER PATTERN CONTINUES LATE THIS AFTERNOON AND
ESPECIALLY TONIGHT AS A POSITIVELY TILTED UPPER TROUGH EJECTS OUT OF
THE ROCKIES. THE PROGRESSIVE NATURE OF THIS TROUGH LEADS TO A
LIMITED WINDOW OF SIGNIFICANT LOW MOISTURE RETURN IN WAKE OF
YESTERDAY'S SYSTEM WITH THE STRONGEST LOW LEVEL MOISTURE
TRANSPORT LIKELY SHUNTED SOUTHEAST OF THE AREA INTO TONIGHT.
HOWEVER, SOME BRIEF RESPECTABLE MID LEVEL MOISTURE RETURN IS
ANTICIPATED AS FAR NORTH AS NORTHERN IN/NORTHWEST OHIO INTO
THIS EVENING WITH 700 MB MIXING RATIOS INCREASING TO 2-3 G/KG.
THIS ISENTROPIC FORCING SHOULD QUICKLY TRANSITION TO MORE
FRONTOGENETIC IN NATURE THIS EVENING AS A STRONG MID LEVEL
BAROCLINIC ZONE SHIFTS INTO THE AREA DOWNSTREAM OF THE MID LEVEL
TROUGH. THE INITIAL ISENTROPIC LIFT WILL LARGELY BE SPENT ON
TOP-DOWN SATURATION, BUT STRONG 700-500 MB UVMS SHOULD
OVERSPREAD THE AREA THIS EVENING IN ASSOCIATION WITH THIS MID
LEVEL BAROCLINIC ZONE/FGEN.
MODEL CROSS SECTIONS CONTINUE TO DEPICT LOW STATIC STABILITY
JUST ABOVE THE THIS MID/UPPER LEVEL FRONTOGENESIS FORCING AND
STRONG WESTERLY UNIDIRECTIONAL SHEAR IN THIS POSITIVELY TILTED
TROUGH SET-UP COULD BE CONDUCIVE FOR SOME EMBEDDED STRONGER
BANDING. THE FAVORABLE OVERLAP OF 700-500 MB LIFT WITH THE DGZ
AND POTENTIAL OF STRONG LIFT IN THIS LAYER COULD SUPPORT SOME
IMPRESSIVE SNOW TO LIQUID RATIOS AROUND 20:1, ESPECIALLY IN ANY
BETTER BANDING THAT DEVELOPS. THE LIMITATIONS TO SNOW
ACCUMULATION TONIGHT INCLUDE THE LESS THAN IMPRESSIVE LOW LEVEL
MOISTURE PROFILES AND PROGRESSIVE NATURE OF MID LEVEL
TROUGH/BRIEF RESIDENCE TIME OF DEEPER MOISTURE PROFILES. HREF
COMPOSITE ANALYSIS WOULD SUGGEST BEST MESOBAND POTENTIAL ROUGHLY
ALONG AND SOUTH OF THE US 24 CORRIDOR WHERE GREATEST CONFIDENCE
IN ADVISORY LEVEL SNOW ACCUMULATIONS EXIST TONIGHT. HOWEVER,
GIVEN POTENTIAL OF GOOD SNOW RATIOS AND COLLABORATION WITH
SURROUNDING OFFICES HAVE INCLUDED ALL OF NORTHERN IN/NORTHWEST
OH IN A WINTER WEATHER ADVISORY FOR 2-4" OF SNOW LOCALIZED
HIGHER AMOUNTS POSSIBLE PARTICULARLY ALONG/SOUTH OF US ROUTE 24.
IMPACTS MAY BE SOMEWHAT MITIGATED BY TIMING OF MOST OF
ACCUMULATION BETWEEN MONDAY EVENING/TUESDAY AM COMMUTES AND THE
FACT THAT WINDS WILL BE QUITE LIGHT WITH THIS SYSTEM. SOME LAKE
EFFECT SNOW SHOWERS ARE EXPECTED TO DEVELOP AS COLDER AIR IS
DRAWN SOUTHWARD EARLY TUESDAY MORNING, BUT SHARP LOW/MID LEVEL
DRYING AND STRONG SUBSIDENCE SHOULD LIMIT OVERALL ACCUMULATION
POTENTIAL.
A QUICK SHOT OF SOME WESTERLY WARM ADVECTION ENSUES FOR TUESDAY
NIGHT/WEDNESDAY AM BEFORE A STRONGER UPPER VORT LOBE DROPS ACROSS
SOUTHERN ONTARIO/NORTHERN GREAT LAKES BRINGING A STRONG COLD FRONT
SOUTHWARD. SOME MINOR ACCUMULATIONS ARE LIKELY GIVEN LARGE SCALE
FORCING/FRONTAL RESPONSE BUT RESIDENCE TIME OF SUPPORTIVE MOISTURE
PROFILES STILL APPEARS VERY LIMITED. LOOKING AHEAD, MEDIUM RANGE
GUIDANCE REMAINS CONSISTENT IN BROAD IDEA OF SEVERAL NORTHWEST FLOW
DISTURBANCES FROM SW CANADA BRINGING PERIODIC SHOTS OF COLD AIR
ADVECTION AND A MAINTENANCE OF BELOW NORMAL TEMPERATURES/SNOW
CHANCES THROUGH THE LONG TERM PERIOD.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 108 AM EST MON DEC 1 2025
FOG WAS FORMING OVER MUCH OF NORTHEAST INDIANA. THE VISIBILITY
AT SMD HAD JUST DROPPED TO A QUARTER OF A MILE AT 0615Z. SOME
PATCHES OF CLOUDS WERE MOVING OVER THE AREA, BUT EXPECT PARTLY
CLOUDY SKIES FOR THE MOST PART THE REST OF THE NIGHT. WENT WITH
A TEMPO 1SM BR AT FWA FOR NOW. TEMPERATURES WERE REALLY RADIATING
OUT AND MAY CAUSE FOG TO FORM VERY RAPIDLY. OTHERWISE, THE FOG
WILL LIFT BY LATE MORNING BEFORE SNOW SPREADS OVER NORTHERN
INDIANA INCLUDING BOTH TERMINALS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
TUESDAY FOR INZ005>009-017-018-024>027-032>034-116-216.
WINTER WEATHER ADVISORY FROM 5 PM EST /4 PM CST/ THIS
AFTERNOON TO 7 AM EST /6 AM CST/ TUESDAY FOR INZ012>015-
020-022-023-103-104-203-204.
OH...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
TUESDAY FOR OHZ001-002-004-005-015-016-024-025.
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EST THIS MORNING FOR LMZ043-
046.
DISCUSSION...MARSILI
AVIATION...SKIPPER
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