474
FXUS63 KIND 060522
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1222 AM EST Sat Dec 6 2025

.KEY MESSAGES...

- Low-end threat for patchy drizzle/flurries Saturday morning

- Wind chills a few degrees on either side of zero expected across
  northern areas this morning

- Chances for snow late Saturday night and Sunday.

&&

.FORECAST UPDATE...
Issued at 918 PM EST Fri Dec 5 2025

No major changes needed to the forecast with conditions generally
evolving as expected. Main focus for the update was to take another
look at the potential for some patchy freezing drizzle/flurries
tomorrow associated with a weak vort max aloft. Models continue to
show little to no precipitation, but with near surface saturation
leading to cloud bases around 500 feet and light winds, at least
some drizzle looks likely. Temperatures at the top of the cloud
layer will be warm enough to limit the potential for ice nuclei, so
freezing drizzle would be the predominant precipitation type.

Main timeframe of concern would be from around 14Z to 18Z with areas
along and north of I-70 and west of I-69 being where concern is
greatest. Areas to the south may have flurries mix in as the cloud
layer will be deeper. Overall confidence remains fairly low as
conditions are marginal, but we`ll continue to monitor trends and
adjust the forecast as needed.

&&

.SHORT TERM (This evening through Saturday)...
Issued at 254 PM EST Fri Dec 5 2025

Surface analysis early this afternoon shows a broad area of high
pressure stretching from east of MA, across the Ohio Valley to the
Lower Mississippi Valley. A cold front was found across MN and the
Dakotas and was part of a broader trough stretching across the upper
midwest. Winds were from the south across Central Indiana due to the
departing high pressure system, however a more moderate gradient was
found ahead of the approaching trough over IL and WI. GOES19 shows
mostly clear skies across Indiana, however some altocu had developed
over Illinois and was headed toward Central Indiana within the
mainly westerly flow aloft. Aloft water vapor showed a weak trough
over the northern plains, but mainly brief zonal flow was in place
over Indiana. The southern tropical jet was streaming across the
gulf coast states providing cloud cover there.

Tonight...

Partly cloudy and cold weather will be expected again tonight.
Models suggest the cold front and associated surface trough will be
approaching Indiana through the night. This will lead to a gradual
increase in cloud cover overnight. Forecast soundings indicate a
gradual saturation aloft this evening as the trough approaches. By
daybreak, time heights suggest the arrival over lower level stratus
along and near the trough axis. Deep moisture or forcing never
arrives with this system. Forecast soundings never become fully
saturated. Thus measurable precipitation is not expected. However,
late tonight as the lower clouds arrive, a few flurries or perhaps
some freezing drizzle cannot be ruled out.

Temperatures will not get as cold tonight as clouds arrive along the
start of mixing as the trough approaches. Lows should only fall to
the lower and middle 20s.

Saturday...

A cloudy, cold and quiet weather day will be in store. Models
suggest the surface trough and cold front will be pushing across
Indiana through the day. Forecast soundings remain rather unchanged,
showing lower level saturation with plentiful dry air aloft.
Furthermore minimal forcing will be present aloft through the day.
Again, lower level moisture will remain present through the day and
will be capable of producing a flurry. Again, no measurable
precipitation will be expected. Thus a mostly cloudy day. Given the
expected clouds, highs should only reach the lower to mid 30s.

&&

.LONG TERM (Saturday night through Friday)...
Issued at 254 PM EST Fri Dec 5 2025

A majority of the long term will feature a fairly stagnant upper
pattern, with strong ridging over the eastern Pacific and a robust
subtropical jet over the SE CONUS. This synoptic set up typically
leads to quickly developing shortwaves in the divergent region of
supergeostrophic jet streaks which will likely lead to a succession
of wave passages across the Great Lakes region Saturday night
through Wednesday. Past Wednesday, a more amplified western ridge
and East Coast trough will likely lead to surges of cold air later
in the week, but with increasing uncertainty on the location of any
low level disturbances.

The first of these waves is expected to reach central Indiana late
Saturday night into Sunday morning. This wave will begin to weaken
some as it encounters upper level convergence near the
aforementioned subtropical jet, but will still have enough lift for
widespread precipitation across Indiana; albeit lighter overall QPF
than areas upstream. The bigger uncertainty lies within
precipitation type as a modest baroclinic zone resides over the
region. Initially precipitation should remain as snowfall, but as
daytime heating occurs, a transition to rain or drizzle is likely
across southern portions of the state. As stated, QPF totals will be
subdued some as the wave weakens, but this still could produce some
impactful snow across the area with potential snow fall totals
ranging from T to 2 inches Sunday morning into the afternoon. Trends
within guidance over the past day have been towards a slightly
weaker system tracking more northerly. Such a track would bring the
best snow chances to the northern half of our CWA and into northern
Indiana. Rain would be favored across southern Indiana during the
day Sunday.

The mid week clippers are expected to pass to the north with 80-90%
of the ensemble solutions favoring this northern track. This
northern track would put central Indiana mostly in the "warm"
sector. Generally, this would keep any precipitation during the day
on Tuesday and Wednesday as rain, but light snow cannot be ruled out
overnight Monday and Tuesday when diurnal cooling helps keep surface
temperatures near to below freezing. The best chances for
precipitation next week are currently expected to be attached with
the second of the two waves; late Tuesday night through Wednesday
evening.

Temperatures: Each of these clippers will have a positive tilt but
should have enough frontogenetic forcing along the baroclinic zone
for modest temperature swings as they pass. This should lead to
pendulum of highs in the in low to upper 30s Sunday, Tuesday and
Wednesday; Whereas highs are likely to remain below freezing Monday,
Thursday and Friday in the wakes of these clippers. During the
colder stretches of Monday, Thursday, and Friday, lows in the single
digits along with a light breeze will likely lead to near zero wind
chills each morning.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1222 AM EST Sat Dec 6 2025

Impacts:

- MVFR Cigs after 09z becoming IFR towards 15Z.
- Low chance for -FZDZ at LAF from 13-16Z.

Discussion:

VFR conditions expected to continue through at least 06Z with MVFR
cigs arriving at LAF toward 09Z. Cigs will continue to fall through
the night with IFR conditions possible after daybreak. Cigs will
then generally remain IFR or MVFR through much of the day. Guidance
suggest potential for brief improvement to VFR towards 00Z Sunday
though uncertainty remains.

There is a low chance for -FZDZ at LAF during the morning, but
confidence is low. There is also a non-zero threat for flurries
toward the afternoon but chances are too low for a mention in the
TAF at this time. Winds will remain southerly at 4-8 kts through
tomorrow morning with a gradual shift to more westerly by the
afternoon.

&&

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

$$

UPDATE...White
SHORT TERM...Puma
LONG TERM...Eckhoff/Updike
AVIATION...Melo