478
FXUS63 KIND 071958
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
258 PM EST Sun Dec 7 2025

.KEY MESSAGES...

- Rain chances are expected Tuesday night through Wednesday,
transitioning to snow showers Wednesday evening through Friday

- Arctic outbreak expected this weekend with low temperatures in the
single digits and potentially dangerous sub-zero wind chill

&&

.SHORT TERM (This evening through Monday)...
Issued at 258 PM EST Sun Dec 7 2025

Surface analysis early this afternoon shows a weak trough stretching
from PA, through the Ohio Valley and to Mississippi and Arkansas.
High pressure was found over Minnesota and the Dakotas. GOES19 shows
plenty of lower level stratus across Central Indiana. Radar showed
this mornings light precipitation had exited the area to the east.
Aloft, water vapor continues to show a quick flow across the CONUS,
with NW flow primarily in place from the northern plains into the
Ohio Valley. A weak trough within the flow was noted over the
southern plains. Temperatures were mainly in the 30s.

Tonight...

Models suggest the weak upper trough moving through the southern
plains will pass across KY and TN overnight. As this feature
approaches, it will interact with the lingering moisture and surface
trough across southern parts of Central Indiana. Forecast soundings
across the southern parts of the forecast area tonight suggest
saturation within the middle and lower levels. HRRR shows as these
pass some snow showers will be possible, with small accumulations
near an inch possible. Elsewhere...the high pressure system over the
upper midwest will be building across Indiana. Time Heights show
some persistent lower level moisture that will keep skies cloudy
through the evening and into the overnight. Although some clearing
is suggested, confidence in that is low, so will attempt to keep to
a cloudy sky overnight. Cold air advection will be in play tonight,
so look for colder lower temperatures in the teens.

Monday...

Dry and cold weather will be expected. Northwest flow is expected to
persist aloft as an upper level weather disturbance passes within
the flow aloft. Lower levels will remain quite dry as a broad area
of high pressure builds across the Great Lakes and Indiana. Forecast
soundings show plentiful dry air within the mid and lower levels,
but saturation aloft. Thus we will expect a partly cloudy sky due to
some passing high clouds. A colder day will be in store as surface
winds will be out of the east due to the high pressure system to the
north. Temperatures will only reach the upper 20s to around 30.

&&

.LONG TERM (Monday night through Sunday)...
Issued at 258 PM EST Sun Dec 7 2025

The long term period features a brief warm up above freezing midweek
before another arctic blast engulfs the region by the end of the
week and into the weekend. Numerous weak weather systems pass
through the Great Lakes this week, bringing periodic chances for
light precipitation.

Tuesday and Wednesday...

Northwesterly flow aloft dominates the weather pattern through the
week with numerous weak systems diving southeast within the active
jet stream, bringing reinforcing shots of arctic air and light
precipitation chances. The first in a series of waves traverses the
upper Great Lakes on Tuesday, with southerly winds bringing a brief
period of relatively warmer air northward into Indiana. The best
forcing for ascent and moisture should remain north of Central
Indiana, closer to the main system, keeping the state mainly dry,
but cloudy all day. A tightening surface pressure gradient and a
stronger LLJ aloft result in breezy conditions during the day with
gusts over 25-30 mph.

"warmer" and windy conditions persist into early Wednesday morning
as yet another system dives southeast into the lower Great Lakes on
the heels of the first one. Southwesterly winds ahead of the surface
cold front will make for a non diurnal temperature curve Tuesday
night with temperatures steady in the upper 30s to mid 40s. The
surface low and associated frontal boundary and precipitation look
to be much further south than the previous system. Moisture profiles
and forcing support light rain over Central and North Central
Indiana early Wednesday morning, transitioning to a mix of rain and
snow showers through the day as colder air advects in behind the
front. Gusty southwest winds over 30 mph at times become
west/northwest behind the front, keeping wind chill below freezing
much of the day.

Thursday into Next Weekend...

A much colder, wintertime weather pattern takes shape late week and
into next weekend as even stronger systems dive southeast out of
Canada, bringing arctic air and snow chances with it.

Mid to long range guidance depicts another weak mid level wave
within the jet moving southeast into the region for the
Thursday/Friday timeframe. Confidence is lower on this set up as the
system looks fairly weak with little to no surface reflection.
Canadian high pressure at the surface may also keep the lower levels
fairly dry, limiting overall precipitation with this next system.
Keeping snow showers in the forecast for Thursday, but expect
changes within the coming days as the finer details become clearer.
Whether this system produces light snow or not, the pattern still
supports much colder temperatures with highs once again remaining
below freezing for the majority of Central Indiana.

Temperatures continue to trend colder each day going into the
weekend as a much deeper trough sets up over the Great Lakes and an
arctic high pressure at the surface advects in some of the coldest
air of the season so far. Despite lower forecast confidence
Thursday, there is high confidence in this arctic outbreak forecast
for the weekend. This pattern supports very windy conditions Friday
into Saturday as the high pressure dives southeast into the Midwest
keeping wind chill values near or below zero for an extended period
of time. High temperatures this weekend may struggle to get out of
the teens with morning lows making a run for the zero degree mark.

Will have to watch what happens Thursday as any accumulating snow
before this arctic outbreak may result in temperatures much colder
than what guidance currently depicts. Even with little or no snow
pack, this incoming airmass supports widespread low temperatures in
the single digits. Any additional snow pack may lead to sub zero
lows, especially for North Central Indiana Saturday and Sunday
nights.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1153 AM EST Sun Dec 7 2025

Impacts:

- MVFR to IFR CIGS expected fop much of this TAF period.
- VFR conditions possible to return overnight, but more confidence
for after 081400Z

Discussion:

MVFR to IFR conditions across the TAF sites are expected to
persist the next 12-18 hours as lower level moisture lingers, in
the wake of slow moving frontal boundary. Time heights and
forecast soundings show moisture trapped beneath an inversion this
afternoon and much of tonight. This will allow for continued MVFR
to IFR conditions.

Overnight, high pressure from the north is expected to build
southeast into Indiana as top down subsidence build across the area.
Also the surface pressure gradient is expected to tighten, which
will provide some mixing and improve visibilities this evening and
overnight.

A dry column is expected by late Monday morning as high pressure
builds across the area.


&&

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

$$

SHORT TERM...Puma
LONG TERM...CM
AVIATION...Puma