281
FXUS63 KIWX 281104
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
604 AM EST Fri Nov 28 2025

.KEY MESSAGES...

- Lake effect snow showers continue this morning with localized
  additional snow accumulations of an inch or two before
  tapering late morning. Slick road conditions likely to
  persist this morning.

- Snow overspreads the area Saturday and continues Saturday
  night. The snow is expected to be heavy at times particularly
  Saturday afternoon into the evening hours. Hazardous holiday
  travel is expected due to the potential of moderate to heavy
  snow, particularly north of US Route 24.

- Snow showers will continue into Sunday, transitioning to lake effect
  snow showers with some additional travel impacts possible.

- More snow is possible Monday night into early Tuesday, but
  confidence in snow accumulations is low at this time.

&&

.DISCUSSION...
Issued at 354 AM EST Fri Nov 28 2025

The primary forecast concern will be approaching winter storm for
Saturday into Saturday night. A Winter Storm Watch will be
maintained for the same areas, with a sharp northwest to southeast
cut-off in snow amounts anticipated. However, confidence remains on
the low to medium side where this gradient will lay out.

Multiple lake effect snow bands persist this morning with the
dominant band extending from eastern Berrien/western Cass MI
Counties through northeast Kosciusko/northern Whitley Counties
in northern Indiana as 0830Z. Lake effect parameters are still
fairly impressive, with inversion heights around 8k feet and
lake induced equilibrium heights between 10-15k feet. Toward
daybreak, near term forecast soundings suggest some drying out
of the DGZ with some synoptic scale subsidence building in
behind departing larger scale mid/upper level trough. Inversion
heights also will lower through mid morning. The above evolution
should result in lake effect snow showers becoming more
cellular in nature after daybreak with lessening potential of
significant additional accumulation after 14Z. Will continue
with the winter weather advisory for Berrien/Cass/St. Joseph
Counties in southern Lower Michigan through 12Z, and will likely
extend the SPS for surroundings counties to continue to mention
potential of slick road conditions this morning.

Otherwise for today, much below normal temperatures expected as low
level thermal trough remains anchored across the Ohio Valley/eastern
Great Lakes. Skies should be mostly sunny outside of the lingering
lake effect clouds.

...Winter Storm for Saturday into Sunday...

The upper level disturbance which will be responsible for
impactful winter weather Saturday into Sunday is currently
making its way across the Pacific northwest with indications in
water vapor imagery this morning of an upper jet streak digging
through upstream portion of this trough. This feature will be
quite progressive as it eventually digs and amplifies across the
northern Rockies tonight/early Saturday. Low level south-
southwest flow will increase sharply in response to this short
wave later tonight into Saturday morning with the nose of this
low level jet impinging on east central IL/NW Indiana late
Saturday morning. A strong retreating low level baroclinic zone
and some speed convergence with this low level jet should induce
some type of advective/frontogenetic snow wing across the
western Great Lakes into NW Indiana Saturday morning. Strong
isentropic ascent will further strengthen during the afternoon,
with 295K isentropic progs indicating 30-45 knots of southerly
flow by 18Z Saturday along with mixing ratios on this surface an
impressive 3-4 g/kg. Always a tricky forecast item in narrowing
down the exact placement of this initial low level
fgen/advective forced band, but some decent snow rates of 0.5-1"
per hour appear possible given strength of this forcing. Above
large scale forcing mechanisms should allow snow to overspread
the area from west to east during the late morning/afternoon
hours.

The most impactful period with this system still appears to be
the late afternoon through evening time period Saturday as
upper level vorticity advection with upstream vort and continued
strong warm/moist advection continues across the area. The
21Z-03Z time period Saturday afternoon/evening could end up
being the period of greatest impact. Model time/height sections
Saturday evening indicate the strongest 700-500 mb lift
affecting the area, with best cross hair signature of co-located
upward vertical motion and elevated DGZ across approximately
northwest third of the area. The nose of an elevated dry punch
and the stronger undirectional mid/upper flow fields by Saturday
evening may also be enough to realize some CSI type banding
Saturday evening which is also the best timing in HREF signal
for snowfall rates in excess of 1 inch per hour centered around
00Z. Confidence in this banding setup is somewhat on the low
side however, as supportive kinematic profiles for this type of
setup will be somewhat dependent on how the mid level, low
predictability diabatic PV anomaly evolves.

Overall track of low level reflection of this system is often not
associated with classic winter storm setup locally, but the
impressive advective fields and deepening nature to compact upper
level system are likely to compensate somewhat. It does appear after
06Z Saturday night that near sfc wet bulbs might overwhelm profiles
to support rain/snow mix or snow/drizzle mix across far southeast
areas as mid level dry slot surges across the Ohio River Valley.
This precip type concern and the fact that snow production
efficiency will likely be optimized far northern IN/southern Lower
MI still looks to produce potential of a strong snowfall gradient
from northwest to southeast in terms of storm total. Storm total
amounts in the 6-10" range still look quite possible across
approximately northwest half of the area with some possible
localized higher amounts if any of the above mesoscale factors
come into play. Additional impactful snow is possible Sunday
with a transition to at least a brief period of lake effect snow
showers. Given this is still primarily a 3rd period concern,
and uncertainty with placement of gradient in snow
amounts/impacts, will hold with a Winter Storm Watch this
morning for previously issued counties.

Mid level height rises follow for Sunday afternoon/evening with
diminishment in lake effect snow showers. Something that may need to
be watched heading into the Monday night/early Tuesday timeframe is
the possibility of some elevated forcing with another highly
progressive eastern Pacific wave. Depending on track, this could
yield just enough of a mid level fgen response for some additional
snow accumulation.

For the long term, no real opportunity seems to exist for
significant moderation in temperatures as highly progressive pattern
and potential weaker clipper systems bring additional rounds of
reinforcing cold advection.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 600 AM EST Fri Nov 28 2025

Lake effect snow showers continue this morning, but greater
impacts with the snow showers should remain north and east of
the terminals. Through the early morning hours, synoptic scale
subsidence will increase which should dry out the dendritic
growth zone. This evolution should result more cellular mode for
lake effect after 13Z. Lowering inversion heights should result
in diminishing lake effect snow showers through midday.
Otherwise, fairly quiet aviation weather this period with
primarily lingering VFR lake effect low clouds (although brief
MVFR cigs possible through mid morning). Quiet weather is
expected this afternoon into tonight, but warm/moist
advection should result in snow overspreading northwest Indiana
toward the end of this forecast period. Greater chances at KSBN
should hold off until after 12Z, so have limited this mention to
PROB30 for now.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Storm Watch from late tonight through Sunday afternoon
     for INZ005>009-012>015-017-018-020-022>027-032>034-103-
     104-116-203-204-216.
OH...Winter Storm Watch from late tonight through Sunday afternoon
     for OHZ001-002-004-005-015-016-024.
MI...Winter Storm Watch from late tonight through Sunday afternoon
     for MIZ078>081-177-277.
     Winter Weather Advisory until 7 AM EST this morning for MIZ078-
     079-177-277.
MARINE...Small Craft Advisory until 8 PM EST this evening for LMZ043.
     Small Craft Advisory until 4 PM EST this afternoon for LMZ046.

&&

$$

DISCUSSION...Marsili
AVIATION...Marsili