402
FXUS63 KIWX 301103
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
603 AM EST Sun Nov 30 2025

.KEY MESSAGES...

- A transition to a mix of light snow, light rain, and drizzle
  will be followed by increasing potential of lake
  effect/enhanced snow showers later this morning into this
  afternoon.

- Additional snow accumulations of 1 to 4 inches are expected
  today with the lake effect snow showers. Gusty west winds to
  30 to 35 mph will result in some blowing and drifting snow.
  Lake effect snow showers diminish tonight.

- Another system will bring some additional light snow
  accumulations Monday night into early Tuesday morning.
  Hazardous travel conditions are possible for the Tuesday
  morning commute.

- Much colder air moves in for middle of the week with another
  chance of snow.

&&

.DISCUSSION...
Issued at 126 PM EST Sat Nov 29 2025

A Winter Storm Warning has been maintained this morning for areas
roughly along/north of US Route 6, while headlines across the south
have been allowed to expire. Lake effect snow showers today and
gusty west winds to 35 mph are the primary reasons for the continued
Winter Storm Warnings.

Low level thermal ridge associated with low level reflection
tracking across southern Lake Michigan vicinity will continue
to shift across far northeast Indiana and northwest Ohio this
morning. Near sfc wet bulbs have been warm enough to allow a
transition to a mix of light rain/drizzle/light snow across most
areas. Can`t completely discount brief freezing drizzle
potential given dry slot punching across the area, but by the
time near sfc wet bulbs for cold enough, near sfc layer should
be drying fairly sharply. Some additional light accumulations
are possible this morning mainly north of US Route 6, but any
additional snow accumulations through daybreak should be minor.

A strong isallobaric rise/fall couplet with the sfc low track and
onset of stronger low level cold advection will allow for a
continued eastward push to sharp west-southwest wind gust increase
across the area early this morning. Passage of this rise/fall
couplet could briefly allow wind gusts as high as 40 mph through
daybreak, but gusts should settle into the 30 to 35 mph range
today. Some patchy drifting/blowing snow is possible, but
current thinking is that the relatively wet nature of the snow
and the mixed precip types early this morning should tend to
discourage significant blowing and drifting snow. For this
reason have cancelled the Winter Storm Warnings for a good
portion of the forecast area outside of the lake effect snow
potential. Have issued an SPS this morning for the areas the
Winter Storm Warnings have been cancelled with a focus on the
strong winds today/potential of some patchy blowing/drifting
snow.

A strong upper vort lobe associated with primary upper trough will
shift across the southern Great Lakes this morning allowing for
slightly better moisture profiles in DGZ to the north of dry slot.
Sharp transition to low level cold advection and this synoptic
enhancement should allow for some moderate to briefly heavy
snow showers to affect much of SW Lower Michigan/NW Indiana
after daybreak. A couple of low level troughs pinwheeling around
departing sfc low and increasingly favorable lake effect
parameters will keep potential of some impactful lake effect
snow showers in place through the day, especially when
considering wind gusts into the 30+ mph range at times. Hires
guidance does continue to suggest some mesovort potential in
association with these low level troughs as they drop south, but
confidence in exact locations impacted remains on the lower
side. The nature of the snow this morning into this afternoon
should also be "drier" in nature and more prone to
blowing/drifting. Some directional shear with synoptic evolution
into early afternoon should keep bands fairly transitory that
should limit snow accums at any one location in the 1-3"/2-4"
range. Impacts could not be notable however, given the
combination of wind/lake effect snow showers and a Winter Storm
Warning has been maintained for these locations. Lake effect
snow showers should diminish tonight.

The active pattern continues again late Monday/Tuesday as an upper
trough digs across the Rockies tonight and acquires positive
tilt across the Central Plains Monday afternoon. Positively
tilted nature of this trough should keep better low level
moisture return confined southeast of the local area, but mid
level moisture return and expected strong mid level baroclinic
zone across the region should set up another round of snow late
Monday into early Tuesday morning. Current forecast is for 1-3"
type accums, but this will need to be watched as decent
instability atop mid level fgen forcing and a fairly deep DGZ
could support a narrow swath of higher accums. In any event,
some impacts to the Tue AM commute appear likely.

Colder air builds in for Tuesday behind this system, with a
reinforcing larger scale frontal boundary sagging across the region
for later Wednesday/Thursday. Some renewed snow chances will
accompany this front, but could be of relatively short duration due
to limited window of favorable moisture profiles. Some of the
coldest air of the season should build in behind this front for
later Wednesday/Thursday. Some moderation in temps expected for
Friday into next weekend, but medium range guidance consensus
suggests potential of active pattern continuing with additional
snow chances.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 558 AM EST Sun Nov 30 2025

Few changes made to the 12Z TAFs. A large area of low pressure
that brought heavy, widespread snow to area late last night is
exiting to the northeast. On the backside of this system, lake
effect snow showers develop downwind of Lake Michigan amid CAA
and breezy conditions. Winds shift from southwest to
west/northwest by the afternoon, with gusts as high as 25 to 35
kts (especially this morning and early afternoon). Lake effect
snow is expected to develop after 12-15Z across southwest Lower
Michigan and northern Indiana. KSBN has much higher chances of
being impacted by lake effect snow today than KFWA. IFR ceilings
and visibilities will prevail all day at KSBN, whereas KFWA may
not see much snow and have fewer restrictions to visibilities.
Gusty winds will create blowing and drifting snow today. Winds
diminish after sunset tonight, becoming light and variable by
early Monday morning.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Storm Warning until 7 PM EST /6 PM CST/ this evening
     for INZ005>008-012-014-103-104-116-203-204.
     Winter Storm Warning until 10 AM EST this morning for INZ009.
OH...Winter Storm Warning until 10 AM EST this morning for OHZ001-
     002.
MI...Winter Storm Warning until 7 PM EST this evening for
     MIZ078>080-177-277.
     Winter Storm Warning until 10 AM EST this morning for MIZ081.
MARINE...Small Craft Advisory until 8 AM EST Monday for LMZ043-046.

&&

$$

DISCUSSION...Marsili
AVIATION...Johnson