664
FXUS63 KIND 101132
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
632 AM EST Wed Dec 10 2025

.KEY MESSAGES...

- Rain moves through this morning; additions rain showers
  transitioning to a rain/snow mix is expected the afternoon

- Wind gusts of 30 to 40 mph throughout the dayinto

- Accumulating snow likely Thursday night into Friday

- Arctic outbreak expected this weekend with low temperatures near
  or below zero...and potentially dangerous sub-zero wind chills

&&

.SHORT TERM (Today through Friday)...
Issued at 250 AM EST Wed Dec 10 2025

Today through Thursday afternoon:

Central Indiana will now face a succession of Alberta Clipper lows
over the coming days, the first of which reached the Great Lakes
region last night, and the last of which will move through on
Saturday. Todays low, will be strong, but will pass well to the
north, keeping temperatures well above freezing (currently 42 in
Indianapolis), minimizing overall impacts to central Indiana.
Numerous showers are expected to pass through most of central
Indiana throughout the morning hours ahead of a strong cold front.
Total rain amounts for central Indiana are likely to be less than a
quarter inch. Despite less overall impacts, the strength of this
system will still have some, mostly due to strong winds. A robust
jet streak will not be far off the surface around 50-60kt, but an
inversion will keep the worst of the winds away from the ground;
still gusts in the 30 to 40 mph range are possible throughout the
morning. As the inversion breaks some late this morning into the
early afternoon, a few gusts may exceed 40, but the jet streak
should be east of central Indiana by the time greatest mixing occurs.

The bulk of the lift will be east of the area by 15Z today, but
there still will be some modest vorticity advection within the
parent trough, along with modest lapse rates that likely will lead
to scattered showers at times late this morning through the
afternoon. This second round of precipitation will be undercut by
some strong CAA during the afternoon hours, of which will likely
lead to some mix of rain and snow at times. This should not
accumulate to much of anything, but a quick light coating of slush
within strongest showers is possible. Winds will continue to be
gusty with the tight pressure gradient and cold advection promoting
mixing down of stronger winds aloft. Wind gusts around 40 mph are
likely, especially north.

The strong push of CAA along with lingering stratus in the broader
cyclonic flow will likely lead to scattered flurries this evening
through early portions of tomorrow. These flurries likely will not
cause any impact. That said, further NE, enhanced low level moisture
downstream of Lake Michigan could allow for a few stronger snow
showers to develop within this same synoptic setup. These snow
showers still likely wont cause much impact but a dusting of snow is
possible tonight into tomorrow in the Muncie, Winchester region.

Thursday evening through Friday morning:

As stated, central Indiana will remain in the path of strong upper
level NW flow, and an efficient set up for quickly developing lows
out of the Canadian Rockies. The second of these systems is expected
to pass through late Thursday through Friday morning. The previous
system brought through strong CAA, of which will sink the baroclinic
zone southward placing central Indiana in a goldilocks zone for both
cyclogenesis and temperatures cold enough for snowfall. This second
low will be weaker than Wednesday`s system, but will likely still
have just as much forcing as it pushes across a strong baroclinic
zone.

These clipper systems along strong temperature gradients typically
produce narrow corridors of moderate QPF, and this one is expected
to be no different. The emphasis is on narrow, as this will lead to
a wide range of QPF outcomes in certain locations, with still almost
48 hours until snowfall onset. This means take each forecast with
some potential of error, as the greatest axis of snowfall could move
25-50 miles depending on where the baroclinic zone is placed
following the cold push after today`s system. Currently, this axis
is most likely to be along the I-74 corridor.

Model soundings showcase a deep isothermal layer as the low arrives
between -6C and -10C. This isn`t the most ideal temperature for
efficient dendrite growth, and therefor SLRs are currently expected
to be somewhere between 10-14:1 across central Indiana. This in
combination with 0.2-0.3 inches of QPF puts the highest likelihood
of snowfall to be between 2 and 4 inches. Slightly higher amounts
are possible where the strongest frontogenetical forcing occurs as
this forcing will likely be slightly further aloft and within more
ideal DGZ temperatures.

Forecast timing has a bit more confidence, as the margin of error is
larger and ensembles have a tighter spread. Currently snow is
expected to reach the Indiana border between 4-7PM on Thursday and
continue through 10AM on Friday morning.

&&

.LONG TERM (Thursday through Tuesday)...
Issued at 250 AM EST Wed Dec 10 2025

Cold pattern to trend from unseasonable to anomalous this weekend,
before moderation expected by end of the period...with additional
light snowfall possible.  H500 cut-off short wave to plunge slightly
within polar flow this weekend...from south-central Canada, across
northern and eastern Great Lakes.  Paving a path for associated
elongated arctic surface high pressure to build/track from North
American Plains during the early weekend...to the Great Lakes/
Midwest by Sunday night.

Vort max speeding around the bottom of the upper cut-off Saturday,
from Quad Cities area into Ohio, will induce another clipper-type
system. Additional light accumulating snowfall is likely for most of
the region within perhaps a 15-hour period around the Saturday to
Saturday evening timeframe.  Bursts of moderate to perhaps briefly
heavy snow are possible, especially north of I-70 which will be
closer to supporting forcing.

Arctic ridge to quickly build into central Indiana on the hind legs
of Saturday`s disturbance, with what should be clearing skies
Saturday night promoting readings near/below zero.  Very cold
conditions...possibly approaching Indianapolis` record low of
negative 4 degrees Sunday morning...should last into Monday morning,
with highs Sunday held below 15F across most zones...and consecutive
early mornings below zero for most locations north of I-70.

Wind chill values to fall to around zero for many spots Friday
night, yet only rebound Saturday to 5-15 degrees for most locations.
Advisory criteria wind chills are currently forecast for both
Saturday night and Sunday night across portions of the region...with
wind chills during the day Sunday likely held below zero for some
northern counties.

Early workweek to feature noticeable moderation back to more
reasonably cold levels...with Monday`s max/min readings hopefully
both noticeably higher than Sunday`s marks.  Low confidence in
potential for freezing drizzle/rain given weak overrunning set-up
with surface readings most likely in the 20s.  Long term to end with
temperatures possibly climbing above freezing.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 631 AM EST Wed Dec 10 2025

Impacts:

- Gusty winds 25 to 35kt tonight through this afternoon

- MVFR ceilings with intermittent IFR within SHRASN.

- Rain this morning, then mix of rain and snow this afternoon.

 Discussion:

Gusty winds from 25-35 kts this morning through the late afternoon.
Following dusk, gusts should begin to subside.

Ceilings have quickly gone down to 2500, and will slowly decrease to
1500 throughout the morning. SHRA and SHRASN will develop late this
morning through the afternoon, of which could push VSBY down to 4SM
and CIGs to 800ft. Overnight, scattered flurries will be possible at
KIND and KLAF, but confidence in occurrence is too low to include in
this issuance.

&&

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

$$

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