983
FXUS63 KIND 170802
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
302 AM EST Wed Dec 17 2025

.KEY MESSAGES...

- Widespread rain likely Thursday with QPF amounts generally ranging
  from 0.5 to 1.25 inches, minor flooding possible

- Wind gusts between 25-35 mph possible Thursday and Thursday night,
  slightly higher gusts cannot be ruled out during the day

- Flash Freeze possible Thursday night/early Friday as temperatures
  could fall 20-30 degrees in 12 hrs

- Above normal temperatures expected next weekend into Christmas
  week

&&

.SHORT TERM (Today and tonight)...
Issued at 302 AM EST Wed Dec 17 2025

Strong surface low pressure over Quebec Canada is rapidly moving
eastward. A cold front extends southwestward from the low, and is
expected to pass through Indiana early this morning. The surface low
is far enough away that we`ll only be experiencing the tail end of
the front, which will be in a weakening/dissipating state as it
passes through. Nevertheless, a weak wind shift and a period of
light precip is possible through sunrise.

Given weak forcing and limited moisture, precip chances will remain
low this morning. Isolated sprinkles or drizzle would be the most
probable outcome during frontal passage. Afterward, clearing skies
are expected allowing temperatures to rebound into the high 30s /
40s this afternoon. Surface high pressure gradually builds in as
well, passing east of Indiana by sunset.

Winds may diminish throughout the day as the high passes through.
However, guidance shows winds increasing out of the south this
evening once the high is to our east. This may reduce the efficiency
of radiational cooling despite relatively clear skies early on and a
residual snow pack. Lows may fail to reach freezing, especially
further south where less snow remains on the ground.

&&

.LONG TERM (Thursday through Tuesday)...
Issued at 302 AM EST Wed Dec 17 2025

Quasi-zonal upper-level flow is anticipated through the majority of
the period with a storm track generally to our north. Such a pattern
typically brings a more seasonable temperature trend as southerly
return flow ahead of each passing system allows for warmer
temperatures. Despite this, occasionally cold shots of air behind
each system are also typical. As such, a temperature roller-coaster
is possible this week into this weekend.

The first in a series of systems approaches tonight with strong
southerly flow ahead of its arrival. Winds may become quite gusty at
times as the MSLP gradient tightens ahead of the approaching system.
Guidance is a bit mixed on how strong these winds get...with CAMs
such at the HRRR showing 30-35kt gusts, and the 3km NAM showing
gusts in the 40-45kt range. Given the rather stable boundary-layer
profile shown in most guidance, we`ll lean towards the 30-35kt
values as more realistic. With such strong southwesterly flow,
temperatures on Thursday after expected to be warm, compared to what
we`ve been seeing, with highs in the 50s.

Despite the surface low itself passing well to our north, roughly
over northern Minnesota, strong forcing from the system`s deep
parent trough will be present. Guidance is in good agreement showing
rain developing Thursday afternoon, becoming heavy at times.
Rainfall totals between 0.5 to 1.25 inches are likely, with the
heaviest amounts further south and east. Additionally, some of the
faster winds aloft may be more effectively mixed downward by heavier
rain showers/embedded thunderstorms. Model soundings show only very
modest instability, even aloft, so this threat appears low.

Interestingly, guidance is in good agreement depicting a double cold
frontal system extending from the parent low over northern
Minnesota. The first front, modeled to arrive late Thursday
afternoon, will help bring the rain to an end and nudge temperatures
down into the 30s/low 40s. The second front, which is much stronger,
arrives Thursday night, with temperatures rapidly falling into the
20s/upper 10s. A flash freeze is possible, but given the multiple
hours between each front and continued breezy conditions...this seems
like a fairly low probability at the moment. Nevertheless, patches
of black ice are likely in spots Friday morning leading to slick
travel conditions.

Snow showers are possible in the post-frontal environment behind the
second front. Model soundings show steep low-level lapse rates and
enough moisture for convective snow showers. Some minor
accumulations are possible, up to a half of an inch at most. Snow
shower activity may persist into the morning hours on Friday, but
will diminish by the afternoon as surface high pressure returns.

This Weekend Onward...

A second weaker system looks to pass well to our north Saturday into
Sunday. Like the first system, a warm up followed by a cool down is
likely. Temperatures rebounding into the 40s on Saturday/Sunday may
quickly be replaced by highs near freezing by Monday. Strength and
timing of the system remains uncertain, as well as magnitude of
moisture return ahead of it. Right now, guidance generally shows
little in the way of precipitation. Some gusty winds are possible if
the low ends up on the stronger side of possible scenarios.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1241 AM EST Wed Dec 17 2025

Impacts:

- Low-level wind shear between 00z to 12z
- SW wind gusts to 20kt before 12z
- MVFR ceilings developing after 00z
- Low-level wind shear returns after 04z

Discussion:

A trough is passing to the north of Indiana and has allowed SW winds
to increase to around 10kt, gusting to 20kt. Additionally, a low-
level jet ahead of the system`s surface cold front is promoting low-
level wind shear around 40kt. Diminishing winds and wind shear,
along with cloud cover, is expected after the front passes around
12z. A low chance of drizzle/sprinkles exists with the front,
especially further northwest near LAF.

Brief surface high pressure should bring VFR conditions with light
and variable winds later this morning into the early afternoon.

However, a second system approaching from the NW will arrive
tonight. Like the previous trough, this one is expected to pass to
our north promoting strong southwesterly winds. Wind shear once
again develops and could exceed 50kt after 06z.

Additionally, strong moisture advection will bring MVFR ceilings
back to central Indiana overnight into Thursday. Rain is likely
after the end of the TAF period during the day on Thursday.


&&

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

$$

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