577
FXUS63 KIND 090740
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
240 AM EST Tue Dec 9 2025

.KEY MESSAGES...

- Near seasonal temperatures today; potential first 40 degree day
  for Indainapolis since November 26th.

- Numerous light rain showers tonight into Wednesday, transitioning
  to occasional snow showers late Wednesday through Friday

- Arctic outbreak expected this weekend with low temperatures down
  to near zero and potentially dangerous sub-zero wind chills

&&

.SHORT TERM (Today and tonight)...
Issued at 237 AM EST Tue Dec 9 2025

Central Indiana is currently in a transition zone with strong SW flow
impinging on a departing area of high pressure. This has resulted
in very weak frontogenetic forcing just north of the area, of which
is producing low clouds and light snow. This area of snow may clip
far northern portions of central Indiana between 08-11Z this morning,
but a majority should fall to the north. Any snow that does fall
will likely not accumulate much, and therefor no impacts are
expected.

Following this, SW flow will increase rapidly, with surface winds
expected to become sustained at 10-15mph with gusts up to 30MPH
beginning shortly after dawn, but continuing throughout the day.
There will be strong WAA within this SW flow, leading to near
seasonal tempertures for the first time since before Thanksgiving.
Current expectation is for afternoon highs around 40 degrees near
Indianapolis, with slightly high temperatures to the south and lower
to the north.

Despite the strong SW flow, the upper level pattern will remain
similar, with clipper lows forming downstream supergeostrophic jet
streaks in the Canadian Rockies. Tonight`s low, will be much
stronger than previous iterations, but will pass well to the north
minimizing impacts to central Indiana. Still, numerous showers are
expected to pass through most of central Indiana tonight ahead of a
strong cold front (more on this in the long term). Total rain
amounts for central Indiana are likely to be less than a quarter
inch.

&&

.LONG TERM (Wednesday through Monday)...
Issued at 237 AM EST Tue Dec 9 2025

Wednesday through Friday...

Wednesday`s robust winds, gusting over 30 MPH, will veer from
southwest to west-northwest, bringing a transition from seasonably
cool and damp conditions, back to mainly subfreezing, yet
reasonably cold conditions through the end of the workweek.

A potent 990 mb surface low, tracking east across the southern Great
Lakes Wednesday, will quickly drag its cold front across central
Indiana during the morning.  Light rain will mix with and change to
snow showers through the midday and afternoon hours from north to
south, as temperatures fall through the 30s during the afternoon.
Vort max embedded within backside of the departing wave should help
coverage of flurries and snow showers increase around the late day
and evening timeframe, especially over northeastern zones that may
catch a lake-enhanced fetch.  Very light or no accumulation is
expected, with minor impacts possible on untreated roads Wednesday
night.

Wednesday`s earlier-day maximum readings, in the low to mid-40s,
will be the last near-normal highs for at least a week as stagnant
cold to very cold pattern returns through mid-month.  A less
pronounced polar surface ridge will slowly build into the Midwest
for the late workweek, with higher confidence in afternoons peaking
near 30F/overnights down to upper teens to mid-20s, and lower
certainty in timing/coverage and amounts/light accumulations of
any snow showers around the Thursday night timeframe that could
produce a thin coating for some areas.

Friday night through Monday...

Continued cold pattern to turn frigid this weekend as elongated
arctic air mass slowly builds into Indiana from its southeastern
corner on Friday night to the ridge`s center by the Sunday night
timeframe.  A bit of overriding Gulf moisture will likely provide
considerable cloudiness through at least the first half of the
weekend, including flurries to possibly light accumulating snow from
what should be an embedded clipper-type weakness crossing the
northern Midwest Saturday, ahead of the core of cold air.

Less cloud cover for the Sunday-Monday timeframes as the dome slides
east over the region should assist the lowest temperature readings.
Highs to be as low as 15-25F for most areas on both Saturday and
Sunday, with probably three very cold nights into the early workweek
featuring generally single digits north and 10-15F south.
Corresponding wind chills will range between values as low as the
negative single digits to single digits.  Assuming the arctic high
continues progressing eastward through the end of the long term,
hopefully a noticeable moderation back to near the freezing mark
will be on tap for the early week.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1237 AM EST Tue Dec 9 2025

Impacts:

- Mixed precip possible late tonight at KLAF.

- MVFR ceilings lowering to IFR tomorrow at KLAF.

- MVFR ceilings developing elsewhere tomorrow morning.

- Gusty winds from the SW at 20-23 kts developing between 12-16Z at
  at all terminals.

 Discussion:

Ahead of a storm system moving through the Great Lakes, winds will
increase aloft late tonight. Speeds will generally be between 25-30
kts only 1kft AGL, not quite sufficient for LLWS. With the increase
in winds will come increasing warm/moist advection and increasing
clouds. Forecast soundings indicate ceilings falling to lower end
MVFR during the morning hours at all terminals with IFR conditions
expected to develop at KLAF. Despite the presence of cloud cover,
sufficient mixing of the winds is expected to develop towards the
surface during the morning hours with gusts from 20-23 kts until
late afternoon.

In addition to the increase in cloud cover, sufficient moistening
will support some scattered precip developing near KLAF, with a
rain/snow mix between 08-12Z. Another round of precip is expected to
develop later tomorrow evening, just in time for the freighter push
at KIND. Soundings indicated ceilings will be just above IFR for IND
at this time.


&&

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

$$

SHORT TERM...Updike
LONG TERM...AGM
AVIATION...Updike