177
FXUS63 KIWX 012320
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
620 PM EST Mon Dec 1 2025

.KEY MESSAGES...

- Accumulating snow tonight, generally between 2 and 4 inches,
  highest along and south of US 24.

- Additional light snow chances (20-70%) late Wednesday afternoon
  into Wednesday night, mainly near Lake Michigan.

- Sub-zero wind chills expected Thursday night.

&&

.DISCUSSION...
Issued at 141 PM EST Mon Dec 1 2025

Tonight`s synoptic snow event remains on target as a potent
positively tiled upper trough and shot of mainly mid level
moisture/ascent swing east through the Ohio Valley and lower Great
Lakes. The initial corridor of moist isentropic ascent likely
allowing top down saturation for light snow into most of our IN and
MI zones 22-00z, reaching nw OH by 00-01z per latest HRRR/ob trends.
The more pronounced slab of deeper mid level ascent and elevated
fgen on the northern fringes of a 60-70 kt 700 mb jet progress
through this evening into early Tuesday with the bulk of the
accumulating snow. Progressive nature to the wave, and limited low
level moisture return, should keep snow amounts/rates from getting
out of hand despite a relatively deep/saturated DGZ. Did opt to
retain higher SLR`s near 15:1 given this deeper DGZ, which when
combined with a model QPF average in 0.15-0.25" still gives a
general 2-4" type snow total, highest along the US 24 corridor where
localized higher amounts up to 5" appear possible within more
intense mesobanding.

Any LES activity in wake of the system should be uneventful as large
scale subsidence and backing/diminishing winds takes a toll on
inversion heights. A period of weak warm advection then emerges
within increasing southwest flow into Tuesday night and Wednesday
with dry conditions prevailing. This occurs in advance of an arctic
cold front expected to drop through Wednesday night in response to a
piece of the polar low pivoting through the northern Great Lakes.
Some snow may accompany the frontal passage late Wednesday afternoon
into Wednesday night despite the lacking moisture recovery, best
chances near Lake MI where enhancement is expected for a time.
Arctic air funnels in behind the front for Thursday and Thursday
night, with sub-zero wind chills anticipated by Thursday night.

Ensemble guidance overall continues to suggest a northwest flow
regime into this weekend and early next week with below normal temps
persisting. A series of mid level impulses look to be anchored
within an active Pacific jet during this time. This could bring a
few opportunities for snow, though timing and track of these
features at this range is of low confidence.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 620 PM EST Mon Dec 1 2025

Widespread light/moderate snow spreading across the area this
evening as a broad midlevel trough swings through the region.
Main change to the forecast was to push up the timing some based
on latest obs and hi-res guidance. Periods of 1/2SM visibility
are likely (especially at KFWA) until 05Z. Snow will exit the
area around 09Z but low stratus will likely remain through much
of the period. There is low confidence in the exact ceiling
height forecast though. Some brief lake effect snow is also
possible at KSBN Tue morning but conditions are not favorable
and most hi-res now shows it missing the terminal. Will leave
in a PROB30 for now but that could be removed.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory until 7 AM EST Tuesday for INZ005>009-
     017-018-024>027-032>034-116-216.
     Winter Weather Advisory until 7 AM EST /6 AM CST/ Tuesday for
     INZ012>015-020-022-023-103-104-203-204.
OH...Winter Weather Advisory until 7 AM EST Tuesday for OHZ001-002-
     004-005-015-016-024-025.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Steinwedel
AVIATION...AGD