320
FXUS63 KIWX 101720
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1220 PM EST Wed Dec 10 2025

.KEY MESSAGES...

- Colder air returns later today and rain will end as some brief
  light snow. 1-2" of lake effect snow is possible this evening
  and overnight.

- 1-3" of snow is then expected mainly south of US-30 on
  Thursday night.

- More light snow is expected this weekend, along with very cold
  air. Wind chill values may drop below -10F Sunday morning.

&&

.DISCUSSION...
Issued at 312 AM EST Wed Dec 10 2025

Our CWA is now firmly in the warm sector of 990mb surface low
crossing southern Lake MI. Several peak gusts around 35 kts over the
last few hours as we almost mix into 50+ kt LLJ just above 900mb.
Strong stable layer will prevent tapping into higher gusts though
and by the time mixing increases with cool/dry air advection later
today, the gradient will be much weaker. Expect a few 35 kt gusts to
continue at times through the morning but should remain safely below
advisory criteria. Almost entire CWA now reporting rain as well with
just Hillsdale reporting 34F and -SN/UP. Warm air will continue
advecting north and bulk of precip through the morning will remain
liquid. Of course, colder air does return by the afternoon as
surface low exits and northwesterly flow returns. Precip will likely
end as some light snow especially in our northern zones but
little/no accumulation expected given commensurate arrival of dry
air and loss of forced ascent. Any accumulating snow will be tied to
a brief window of marginally favorable conditions for LES this
evening and overnight. NNW flow pushes 850mb temps to around -13C
tonight but inversion heights are a paltry 5 kft and 0-2km theta-e
lapse rates remain positive. A brief window of weak low level
convergence around 21Z this afternoon will probably be the best
chance for a slightly more organized band. Winds slowly back
overnight though further limiting the lake response. Overall an
isolated 1-2" in our NW zones is all that is anticipated through Thu
AM. Overnight lows do drop back into the teens. Winds relax tonight
but remain steady near 10 mph yielding Thu AM wind chills in the
single digits.

Next clipper system arrives Thu night with the next round of light
snow. CVA forcing is much weaker with this system. Expect a classic
clipper setup with just a brief and narrow region of WAA/fgen
sliding through the region Thu night. Expect a fairly tight gradient
in QPF/snowfall given such narrow, modest forcing in an otherwise
dry/stable environment. Several of the newest 00Z deterministic runs
even suggest areas along/north of US-30 will remain entirely dry.
Still some uncertainty in exact track based on ensemble guidance
though, so maintained some lower PoP`s/QPF further north but do
expect the highest totals (likely 1-3") to remain south of US-30.

Still expecting another clipper this weekend with very cold air.
Details on snow amounts, particularly the lake effect component, are
difficult to pinpoint this far out but do expect temps around zero
and wind chills of -10 to -20F, especially Sunday morning. Luckily
this cold/snowy pattern looks to finally break by next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1211 PM EST Wed Dec 10 2025

The primary surface cold front is working its way across
northern Indiana this afternoon with banding of light snow along
an associated low level fgen axis. This should produce most of
the snowfall within a 2-3 hour window at KSBN, while initially
more marginal low level temps at KFWA make snow accumulations
of less confidence. Radar imagery this afternoon is already
depicting a more dominant single band across southern Lake
Michigan, and this band is expected to shift eastward through
the remainder of the afternoon possibly affecting KSBN as early
as 21Z-22Z. Some of these lake effect snow showers could make it
to KFWA, but in a much weaker state, and see no reason to
deviate from previous mention of PROB30 from 01Z to 07Z. Lake
effect snow showers should diminish late tonight. Initial IFR
cigs should improve to lower end MVFR as winds shift to
northwest behind a cold front later this afternoon, with
additional MVFR cigs tonight as lake effect becomes dominant.
Currently expecting improvement to VFR low clouds at KFWA after
12Z, but lake effect processes should keep MVFR cigs at KSBN
into Thursday morning

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Gale Warning until 7 PM EST this evening for LMZ043-046.

&&

$$

DISCUSSION...AGD
AVIATION...Marsili