478
FXUS63 KIWX 091741
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1241 PM EST SUN NOV 9 2025
KEY MESSAGES
- MULTIPLE ROUNDS OF LAKE EFFECT SNOW ARE EXPECTED THROUGH
MONDAY NIGHT.
- THE HEAVIEST SNOW IS EXPECTED FROM 6PM - 1AM (EST) TONIGHT
WHERE SNOWFALL RATES COULD EXCEED 2-3" PER HOUR NEAR LAKE
MICHIGAN.
- AFTER A LULL IN LAKE EFFECT SNOW MONDAY MORNING, ADDITIONAL
ACCUMULATIONS ARE EXPECTED MONDAY AFTERNOON AND EVENING.
- IT WILL ALSO BE BREEZY WITH GUSTS UP TO 25-30 MPH, MAINLY THIS
EVENING. TRAVEL WILL BE DIFFICULT IN AREAS NEAR LAKE MICHIGAN.
- SNOW SHOWERS ARE ALSO EXPECTED AWAY FROM THE LAKE LATE TONIGHT
INTO EARLY MONDAY AND ANOTHER 1-2" IS POSSIBLE FOR MUCH OF THE
AREA.
DISCUSSION
ISSUED AT 430 AM EST SUN NOV 9 2025
COMPLICATED FORECAST FOR THE NEXT 48 HOURS WITH MULTIPLE ROUNDS OF
SNOW EXPECTED AND SOME SIZABLE BREAKS IN BETWEEN.
ROUND 1 TODAY...
LIGHT SNOW HAS ALREADY BEEN OCCURRING IN COUNTIES NORTH OF US-24
OVERNIGHT ASSOCIATED WITH A ROBUST MIDLEVEL SHORTWAVE AIDED BY SOME
DECENT UPPER JET DYNAMICS. ISENTROPIC ASCENT AND FGEN HAVE LIT UP A
SWATH OF MODERATE PRECIP AS THE SURFACE LOW CONTINUES TO STRENGTHEN.
THE ONE MAJOR CHANGE WITH THIS SYSTEM WAS COLDER TEMPS ALLOWING MORE
PRECIP TO FALL AS SNOW. SNOW BEGAN EARLY OVERNIGHT AND MANY AREAS
ARE REPORTING AN INCH OR TWO ON GRASSY/ELEVATED SURFACES. IMPACTS TO
THE ROADS SHOULD CONTINUE TO BE MINIMAL GIVEN WARM GROUND/PAVEMENT
AND AIR TEMPS ONLY 32-34F BUT SOME SLUSHY ACCUMS POSSIBLE ON THE
ROADS IN OUR NORTHERN ZONES THROUGH MORNING.
THE MAIN IMPACT OF COLDER TEMPS WILL BE FELT LATER TODAY WITH THE
FIRST LAKE EFFECT BAND. REGIONAL RADAR MOSAIC ALREADY SHOWS A
FORMIDABLE BAND TAKING SHAPE ACROSS NORTHERN LAKE MI. THIS BAND WILL
ONLY STRENGTHEN WITH TIME AS NORTHERLY FLOW LOCKS IN AND MAXIMIZES
FETCH ACROSS LAKES MICHIGAN AND SUPERIOR. FORECAST SOUNDINGS SHOW
INVERSION HEIGHTS IN SE LAKE MI CLIMBING TO 10KFT BY MIDDAY AS 700MB
TEMPS DROP TO ALMOST -20C. EARLIER INDICATIONS WERE THAT THIS BAND
WOULD STRUGGLE TO ORGANIZE AND WOULD BATTLE SOME MELTING DURING THE
DAYTIME HOURS. NEITHER APPEAR TO BE AS MUCH OF A CONCERN. THE ONLY
LIMITING FACTOR FOR THIS BAND WILL BE THAT IT IS CONSTANTLY MOVING
FROM WEST TO EAST ACROSS OUR AREA DURING THE EARLY AFTERNOON WHICH
WILL LIMIT SNOWFALL TOTALS IN ANY ONE SPOT. HOWEVER, IMPRESSIVE
THERMODYNAMICS COULD STILL YIELD SNOWFALL RATES OF 1-2"/HOUR
YIELDING A QUICK 2-5" IN ONLY A FEW HOURS. GIVEN THIS CONCERN ALONG
WITH SOME SNOW ALREADY ACCUMULATING AND SUBSEQUENTLY COLDER TEMPS
TODAY, HAVE DECIDED TO PUSH UP THE START TIME OF THE WARNING TO
BEGIN AT 16Z. THERE WILL BE A MINOR GAP BETWEEN THIS INITIAL BAND
AND THE PRIMARY BAND/MESOLOW ANTICIPATED THIS EVENING BUT ONLY FROM
ROUGHLY 21-00Z.
ROUND 2 THIS EVENING...
A PIECE OF THE ARCTIC UPPER LOW WILL COME SLAMMING DOWN THE LAKE
THIS EVENING AND BRING WITH IT OUR BEST CHANCE FOR SIGNIFICANT SNOW
ACCUMULATIONS. EQUILIBRIUM HEIGHTS (ALREADY IMPRESSIVE BY THIS
AFTERNOON) SOAR ALL THE WAY TO 20 KFT WITH ESTIMATES OF OVER 1000
J/KG OF LAKE-INDUCED CAPE THANKS IN PART TO 500MB TEMPS DROPPING TO
AN INCREDIBLE -40C. THERMODYNAMICS OF THIS MAGNITUDE ARE RARELY
SEEN. FURTHERMORE, MODELS CONTINUE TO HINT AT A MESOLOW DEVELOPING
THAT, IF TRUE, COULD GENERATE SNOWFALL RATES WELL IN EXCESS OF
3"/HOUR WHEREVER IT COMES ONSHORE. OF COURSE, THE DIFFICULTY
CONTINUES TO BE WHERE DOES THIS HAPPEN AND HOW LONG DOES THE
ATTACHED SINGLE BAND STAY IN ONE PLACE. HERE AGAIN THE SAVING GRACE
FOR OUR AREA IS THAT IT WILL BE MOVING AROUND. CURRENT BEST GUESS IS
THAT THE MESOLOW/DOMINANT BAND CLIPS BERRIEN, LA PORTE, AND MAYBE
WESTERN ST. JOSEPH (IN) BEFORE MOVING SOUTHWEST AND SETTING UP A
MORE ENDURING DOMINANT BAND SOMEWHERE NEAR/IN CHICAGO. THIS MAKES
FOR A DIFFICULT FORECAST IN OUR AREA BECAUSE THE SNOW WITH THIS
PARTICULAR ROUND WON'T LAST A LONG TIME BUT HAS THE POTENTIAL TO
COME DOWN EXTREMELY FAST AND HEAVY. THIS PERIOD FROM ROUGHLY 23-06Z
WILL BE THE PERIOD THAT WILL MAKE OR BREAK THIS EVENT FOR US.
ROUND 3 MONDAY AFTERNOON/EVENING...
AFTER "ROUND 2" THERE WILL BE A SIZABLE BREAK IN TRUE LAKE EFFECT
ACTIVITY FOR OUR AREA. DOMINANT BAND WILL SET UP OVER OR JUST SOUTH
OF CHICAGO IN NNE FLOW, LEAVING OUR NW AREA DRY AND LIKELY EVEN
SUNNY FOR A TIME MONDAY MORNING (ROUGHLY 12-18Z). THERE WILL STILL
BE SNOW SHOWERS ACROSS THE ENTIRE AREA ASSOCIATED WITH THE VORT LOBE
ITSELF (AND PERHAPS SOME INFLUENCE FROM LAKE HURON) ROUGHLY 09-15Z
AND IT IS IMPORTANT TO NOTE THAT WHILE THE FOCUS IS NEAR LAKE MI OUR
ENTIRE AREA WILL SEE SOME SNOW TONIGHT INTO MON.
FLOW BACKS AROUND TO THE NW BY MONDAY AFTERNOON AND THIS WILL SEND
DOMINANT BAND BACK INTO OUR AREA FOR ANOTHER VISIT. LAKE-INDUCED
INSTABILITY NOT QUITE AS IMPRESSIVE FOR THIS ROUND BUT INVERSION
HEIGHTS ARE STILL OVER 12 KFT. BIGGEST LIMITING FACTOR WILL BE THE
DISRUPTION ASSOCIATED WITH BACKING WINDS THAT WILL TEAR APART WHAT
WOULD OTHERWISE BE AN IMPRESSIVE DOMINANT BAND. STILL, ANOTHER
ROUND WITH A FEW HOURS OF 1-2"/HOUR RATES IS POSSIBLE YIELDING
ANOTHER QUICK 2-4". THIS ACTIVITY WILL NOT ONLY LINGER WELL AFTER
00Z MON EVENING BUT WILL EXTEND MUCH FURTHER INLAND POTENTIALLY
BRINGING A QUICK INCH OR TWO TO THE FORT WAYNE VICINITY.
PUTTING IT ALL TOGETHER EXPECT STORM TOTAL AMOUNTS OF 5-11" IN THE
WARNING AREA WITH HIGHER AMOUNTS LIKELY IF A WELL-DEVELOPED MESOLOW
CRASHES INTO OUT AREA THIS EVENING. EXPECT A GENERAL 2-5" IN AREAS
UNDER THE ADVISORY WITH 1-3" ELSEWHERE. IT WILL ALSO BE BREEZY WITH
GUSTS UP TO 30 MPH THIS AFTERNOON AND EVENING AND UP TO 25 MPH ON
MONDAY.
THE SIZABLE GAP IN LES EXPECTED MONDAY MORNING MADE THE HEADLINE
DECISION DIFFICULT. IT'S DIFFICULT TO CARRY A WINTER STORM WARNING
FOR ALMOST EIGHT HOURS WITH LITTLE/NO ADDITIONAL SNOW FALLING.
HOWEVER, WITH THE POTENTIAL FOR HIGH-END AMOUNTS THIS EVENING AND
THE EXPECTED WIND, IMPACTS COULD EASILY LINGER THROUGH MON MORNING
AND CONTINUE RIGHT THROUGH TO SNOW STARTING AGAIN MON AFTERNOON.
IMPACTS WILL ALSO LIKELY BE SIGNIFICANTLY HEIGHTENED GIVEN THIS IS
THE FIRST SNOW OF THE SEASON. THEREFORE DECIDED TO JUST RUN ONE LONG
WARNING THROUGH THE ENTIRE EVENT AND HEAVILY MESSAGE THE EXPECTED
GAP IN FALLING SNOW MON AM. IF THE MESOLOW/DOMINANT BAND LARGELY
MISSES OUR AREA THIS EVENING THEN WE CAN DOWNGRADE ACCORDINGLY.
STILL EXPECT A WARM FRONT TO LIFT THROUGH THE AREA ON TUE WITH SOME
VERY LIGHT RAIN OR SNOW POSSIBLE. MOST AREAS WILL PROBABLY REMAIN
DRY THOUGH GIVEN LIMITED FORCING AND MID/UPPER SUPPORT. REST OF THE
FORECAST IS DRY WITH WARMING TEMPS. THE NEXT CHANCE OF PRECIP (RAIN)
WILL NOT BE UNTIL EARLY NEXT WEEK.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 1240 PM EST SUN NOV 9 2025
A LAKE EFFECT SNOW BAND CONTINUES TO SHIFT EAST ACROSS NORTHWEST
INDIANA THIS AFTERNOON. COLD LOW LEVEL PROFILES ARE BEING OFFSET
CLOSER TO LAKE MICHIGAN BY MILD NEAR SFC TEMPERATURES FROM FLOW
TRAJECTORIES OFF A WARM LAKE MICHIGAN. AS THIS BAND APPROACHES,
KSBN, THERE COULD BE SOME SHORT-LIVED PTYPE ISSUES OF RAIN/SNOW
BUT EXPECTING KSBN TO BE FAR ENOUGH AWAY FROM LAKE MICHIGAN TO
SUPPORT MAINLY SNOW. OTHERWISE, IT STILL APPEARS AS THOUGH THIS
EVENING WILL BE POTENTIAL OF HIGHEST IMPACT LAKE EFFECT SNOW
SHOWERS AS THERMAL PROFILES BECOME QUITE IMPRESSIVE FOR LAKE
EFFECT SNOW. A MESOLOW IS ALSO EXPECTED TO TAKE SHAKE WHICH
SHOULD EVENTUALLY TAKE FOCUS OF SNOW WEST OF KSBN BY LATE
EVENING OR EARLY OVERNIGHT. OCCASIONAL IFR/LIFR CONDITIONS ARE
POSSIBLE IN THE HEAVIER LAKE EFFECT SNOW SHOWERS THIS EVENING. A
LULL IN LAKE EFFECT SNOW SHOWERS IS EXPECTED OVERNIGHT INTO
MONDAY MORNING BEFORE BAND DISPLACED TO THE WEST SHIFTS BACK TO
THE EAST. AT THIS TIME, THIS IMPACT DOES NOT APPEAR MORE LIKELY
UNTIL THE VERY END OR JUST AFTER THIS FORECAST VALID PERIOD. IN
TERMS OF KFWA, A PERIOD OF SNOW SHOWERS MAY ACCOMPANY SOUTHWARD
SHIFT OF UPPER LOW/MESOVORT FROM MID EVENING TO EARLY OVERNIGHT,
BUT DUE TO LOWER CONFIDENCE, WILL ONLY INCLUDE TEMPO MVFR
CONDITIONS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 PM EST
MONDAY FOR INZ005-116-216.
WINTER STORM WARNING UNTIL 7 PM EST /6 PM CST/ MONDAY FOR
INZ012-014-103-104-203-204.
WINTER WEATHER ADVISORY UNTIL 7 PM EST MONDAY FOR INZ013-015.
OH...NONE.
MI...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 11 PM EST
MONDAY FOR MIZ078.
WINTER STORM WARNING UNTIL 7 PM EST MONDAY FOR MIZ177-277.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST TUESDAY FOR LMZ043-046.
DISCUSSION...AGD
AVIATION...MARSILI
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