683
FXUS63 KIND 032331
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
631 PM EST Wed Dec 3 2025

.KEY MESSAGES...

- Patchy fog possible early tonight

- Light snow likely tonight, minor accumulations possible before
  Thursday morning commute

- Wind chills of few degrees either side of zero will be across
  northern areas early Thursday and again Thursday night/early
  Friday.

- Snow is possible Sunday and again next Tuesday.

&&

.SHORT TERM (This evening through Thursday)...
Issued at 303 PM EST Wed Dec 3 2025

Surface analysis shows a cold front approaching Indiana from the
northwest, extending from northern Missouri to just north of Chicago
as of 2pm. Southerly flow ahead of the front has increased to
between 10-15kt. ACARS soundings out of IND show substantial warm
air advection occurring aloft, just a couple hundred feet off the
ground. However, a strong inversion has allowed widespread stratus
to persist through the afternoon. Temperatures at the surface have
been lower than guidance so far today. Some breaks are beginning to
be noted, however, and a late-day rebound may occur for some spots.

Guidance shows winds diminishing this evening due to the MSLP
gradient weakening as the front approaches. Should clearing continue
into the early evening hours, some patchy fog is possible given a
very moist boundary layer currently in place. Dew point depressions
are only about 5 degrees as of this writing. Fog potential will be
mitigated by thick mid-level cloud cover above the stratus.
Therefore we`ve capped fog at patchy in the forecast. Fog will be
confined to the pre-frontal environment, so we`ve also removed
mention of fog beyond 06z.

Light precipitation has developed along the front over northern
Illinois and into northern Indiana. This activity has been fighting
some mid-level dry air, which shows up on the IND ACARS soundings as
well between 900-700mb. Our primary forecast challenge tonight is
whether precipitation will be able to overcome the dry air as it
heads south. Guidance hints at a few poorly-organized vorticity
filaments riding along the front, which may produce some modest
large-scale lift at times. Jet dynamics are a bit mixed, with
Indiana sitting below a jet entrance region but also an area of
upper-level confluence. Warm air advection / isentropic lift also
diminishes with time as southerly flow ahead of the front weakens.
Putting all this together, we`ll have enough forcing for at best
light precipitation. The precip should be able to overcome the dry
air as no new dry air is being advected northward (limited moisture
advection as well), so it would just be a matter of time.

In terms of amounts, a dusting to a half of an inch seems
reasonable. An isolated amount up to an inch would be the reasonable
worst case scenario.

The front itself passes through central Indiana between 02z-06z,
with a brief period of gusty NNW winds and strong cold air
advection. Temperatures rapidly dropping into the teens and single
digits is likely, with wind chills by sunrise Thursday near or a bit
below zero. High temps on Thursday will be limited by ongoing cold
air advection and residual low stratus, which could once again
linger more than guidance suggests. Expect highs in the upper teens
(north) to mid 20s (south). Very cold low temperatures in the teens
and single digits are expected again Thursday night.

&&

.LONG TERM (Thursday night through Wednesday)...
Issued at 303 PM EST Wed Dec 3 2025

Ensemble guidance shows broad troughing over the Midwest and
northeastern US. This pattern generally favors cooler-than-average
weather over Indiana, which has been the case for the past week or
so.

Some differences are noted within the large-scale pattern,
however. Namely, the lack of troughing over the southwestern US.
This troughing has been the source of recent snowfall as systems
eject from the southern Rockies and track east/northeastward. Our
primary source of synoptic activity will switch to the Pacific
Northwest, with systems coming ashore over Washington before diving
southeastward. These systems (clippers) are typically weak with
limited moisture.

Guidance shows a few of these system approach throughout the week,
passing quietly to our north. The next one of any potential
consequence may be this weekend. Almost all guidance has trended
downward in terms of impacts, however. We`ll retain low PoPs for
Sunday. A second system may approach early next week, but guidance
diverges rapidly at this point so forecast confidence is low.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 630 PM EST Wed Dec 3 2025

Impacts:

-MVFR to IFR cigs through much of the period, improving after 16Z
-Brief MVFR to IFR vsbys due to snow/patchy fog after 04Z through 12Z
-Wind shift from 230 to 330 after 04Z

Discussion:

MVFR cigs will gradually drop to IFR after 05Z and bounce between
high IFR and low MVFR through 14Z when low clouds should clear out
between then and 18Z. Light snow is then likely, especially at HUF
and BMG from 04Z through 09Z with vsbys generally MVFR but briefly
IFR at times. Snow should end towards 09Z with the potential for
some lingering MVFR vsbys due to patchy fog. Winds will remain in
the 8 to 12kt range through the TAF period with southwesterly winds
becoming northwesterly to northerly after 04Z.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Eckhoff
LONG TERM...Eckhoff
AVIATION...White