989
FXUS63 KIWX 100812
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
312 AM 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 /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1252 AM EST Wed Dec 10 2025

Predominantly VFR/MVFR conditions to start the period at both
terminals, deteriorating towards IFR for a time this morning.
There is potential for LIFR visibilities at KSBN between 14-18z
(prob30) but confidence wasn`t high enough for a tempo just
yet. Rain/drizzle overnight will gradually change over to snow
from west to east through Wednesday as temperatures fall behind
a cold front, with mixing starting at around 13z at KSBN and 15Z
at KFWA. Variable model guidance with this system with regards
to visibilities/ceilings, particularly in the 14-19z time frame
with everything from 500-2500 ft suggested with 1/2 to 6SM
visibilities. Guidance was overly pessimistic with this system
yesterday-and some of the lower guidance already too low as of
this issuance. Went middle of the road and tried to highlight
potential for the worst conditions with prob30 group for now.
Light rain/drizzle over much of the area at the moment, with
southwest winds gusting to around 25 knots. Winds shift
northwest with gusts up to around 30kts through the afternoon.
LLWS at both sites in the 50-55kt range through 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...MCD