Lafayette, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

820
FXUS63 KIND 281744
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1244 PM EST Sun Dec 28 2025

.KEY MESSAGES...

- Near record highs today

- Narrow convective line with the potential for brief wind gusts in
  excess of 50mph and perhaps a tornado will move across central
  Indiana early this evening

- Peak wind gusts at 45 to 50mph at times tonight and Monday

- Rapidly falling temperatures into the teens and 20s tonight and
  Monday with wind chill values near zero at times

- Much colder weather through the upcoming week with chances for
  light snow Wednesday night

&&

.SHORT TERM (This evening through Monday)...
Issued at 1244 PM EST Sun Dec 28 2025

The primary focus for the short term period will be tracking a
potent system this evening into tonight which will bring a line of
strong to severe storms, strong gradient winds, and a 40+ degree
temperature drop over 6 to 9 hours. As of early this afternoon,
skies remain mostly cloudy across the state with winds gradually
ramping up as the LLJ strengthens. The surface low associated with
the system continues to deepen as it moves across northern Illinois
with showers and storms were moving across northern Illinois. These
are expected to remain northwest of the forecast area through the
remainder of the afternoon with the main timeframe for concern from
around 5PM to 10PM as the aforementioned line moves in.

Severe Threat.

Dew points across both central Indiana have risen into the low 60s
with most areas now seeing temperatures in the low to mid 60s with
increasing confidence in a narrow axis of even higher dewpoints just
ahead of the front. High resolution models continue to pick up on a
narrow axis of higher dewpoints just ahead of the front which will
allow for ML CAPE values of 500-800 j/kg across Illinois where
convective initiation is expected. Dynamic indices are all favorable
for convection with 0-1km shear upwards of 20kts and SRH values
upwards of 300/400 m2/s2. The main question will be how far east the
better instability stretches with the loss of diurnal heating
towards the time the line crosses into western Indiana. The tornado
threat will mainly be across the western and northwestern portions
of the forecast area before the loss of instability begins to
transition the threat to just damaging winds. With the line expected
to become organized, the severe threat will persist through all of
central Indiana even as instability drops. While the greater threat
will be across Illinois, do have concerns in widespread 40-55 mph
winds along the line with sporadic 60-65 mph winds and at least a
few kinks in the line which could produce tornadoes.

Gradient Wind Threat.

Outside of storms, gradient winds will gust 40-50 mph along and just
behind the line of storms with the stronger gusts with occasional
gusts of 35-50 mph continuing through the night. Model soundings
show that as the CAA strengthens, the boundary layer never fully
decouples with mixing up to around 3000ft through the night. The
boundary layer winds will be strongest towards daybreak tomorrow
which is when the confidence is highest in the higher-end gusts.
Winds aloft will gradually weaken through the day as the system
exits which will bring an end to the stronger gusts by the evening.

Flash Freeze and Snow Threat.

The other focus for tonight will be the temperature crash in the
aftermath of the frontal passage with a drop from the 60s into the
20s in around six hours. This presents a risk for a flash freeze.
While strong post-frontal winds will help evaporate some surface
moisture, any residual standing water on untreated surfaces,
particularly bridges and overpasses, will likely freeze rapidly
before it can dry along with areas where water had ponded earlier in
the night. The snow threat looks increasingly minimal tonight as
there will be little to no forcing by the time the temperatures drop
below freezing. Some snow showers will be possible across the
northern counties tomorrow along with flurries to the south
associated with the backend of the system but any lake effect snow
will remain north of the forecast area based on expected wind fields.

&&

.LONG TERM (Monday Night through Saturday)...
Issued at 320 AM EST Sun Dec 28 2025

A much colder weather, more seasonable winter pattern sets up for
next week across the Great Lakes and Ohio Valley. A few weak clipper
systems bring light snow chances midweek, but overall no major
weather systems of concern in the long term other than minor systems
passing through.

Over the next week, the Eastern CONUS will feel the effects of a
negative NAO as blocking increases over Canada and the North
Atlantic. As a result, deep troughing remains in place over Southern
Canada with a strong northwest flow pattern setting up from
northwestern Canada down into the Ohio Valley. The upper jet remains
strong through the period in response to a sharp low level thermal
gradient across the CONUS, with Indiana entrenched within the colder
arctic airmass at the surface. The main focus in the long term will
be on a few weak clippers traversing southeast within the upper flow
into the Great Lakes. Uncertainty increases by next weekend and into
the following week as long range guidance/ensembles hint at a more
progressive and relatively milder pattern setting up with more
influence from the southern branch of the upper jet.

Mid Next Week...

The first in a series of clipper systems drops southeast into the
upper Great Lakes on Tuesday. The jet streak and associated surface
reflection track closer to the Canadian border, keeping the best
forcing for ascent and any precipitation north of Central Indiana.
The main impacts from this system will be a surface wind shift to
the west-southwest and a brief temperature moderation as weak warm
air advection modifies the arctic airmass in place. West-southwest
winds Tuesday work to slowly erode the cold air at the surface;
however temperatures may still struggle to get out of the upper 20s
much of the day. A non-diurnal temperature curve is expected Tuesday
evening as elevated winds and continued weak WAA keep temperatures
steady in the upper 20s to low 30s through the night. A brief period
of above freezing temperatures is expected on Wednesday before
Canadian high pressure moving in from the northwest works to pull
the arctic airmass back south into Indiana.

The next wave within the upper jet dives southeast out of Canada
into the Ohio Valley Wednesday night into Thursday morning. This is
the one to watch for the possibility for light snowfall across
Central Indiana. While this clipper looks fairly weak with little to
no surface reflection and only a weak mid level perturbation, there
may be enough lift under the exit region of the jet to squeeze out
light snow showers locally. Confidence is low in finer details of
this clipper as it is several days away and details may change
between now and then. But the overall pattern setting up supports
below freezing temperatures and the chance for light snow showers
Wednesday night into Thursday. Keeping PoPs at or below 40 percent
00z-12z Thursday for now to keep snow shower wording in the
forecast.

.Next Weekend...

Going into the weekend, high pressure extending from NW Canada into
the Ohio Valley slowly shifts eastward; however low level
temperatures will be slow to respond as the colder, dense airmass at
the surface slowly retreats. Longer range guidance and ensembles
hint at a system developing in the Plains then moving across the
Southern CONUS this weekend. Coming out of a blocking northwest flow
pattern, it is expected that guidance will not handle this
transition well, so low confidence remains in the forecast for next
weekend. Keeping the forecast on the drier side with temperatures
moderating back above freezing for the weekend. Introducing low
PoPs, under 20 perfect for the weekend to account for the potential
for a system over the Southern US possibly bringing moisture far
enough north for precipitation locally. Will update the long term
accordingly as confidence increases in the overall pattern evolution
as the colder northwesterly flow pattern finally breaks.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1244 PM EST Sun Dec 28 2025

Impacts:

- MVFR cigs expected through the TAF period with brief IFR at times
- Line of showers and storms this evening, mainly from 23Z to
01Z
- Southwest winds gusts peaking at 25-30kts this afternoon, veering
  to westerly tonight and increasing to 40kts
- Flurries and light snow tomorrow, highest chances at LAF

Discussion:

MVFR conditions expected through the TAF period with cigs
occasionally dropping to IFR at times through 04Z. A line of showers
and storms is expected to move from west to east this evening from
around 23Z to 01Z with a wind shift from the south to west in the
aftermath of the storms. Winds will begin to gust to around 25kts
after 20Z with gusts of 30-40kts in the aftermath of the storms
through the night. The stronger winds will begin to relax towards
the afternoon tomorrow with the potential of seeing flurries and
light snow at times. Confidence in accumulating snow is low with
best chances towards LAF.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 6 PM this evening to 5 PM EST Monday for
INZ021-028>031-035>049-051>057-060>065-067>072.

&&

$$

SHORT TERM...White
LONG TERM...CM
AVIATION...White