Lafayette, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

090
FXUS63 KIND 010506
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1206 AM EST Mon Dec 1 2025

.KEY MESSAGES...

- Mostly Cloudy and cold overnight.

- Accumulating snow possible Monday night into Tuesday morning.

- Wind chills at night...into the teens through Monday night...down
  to possibly near zero Wednesday night.

- Another accumulating snow event is possible Friday with mix
  precip also possible into next weekend.

&&

.FORECAST UPDATE...
Issued at 906 PM EST Sun Nov 30 2025

Surface analysis late this evening shows Low pressure over SW Quebec
and cyclonic lower level flow across the Great Lakes. A cold,
Canadian high pressure system was centered over SD/NB/IA, building
southeast. GOES19 shows abundant cloud cover still over Central
Indiana. Lake cloud was still streaming off of Lake Michigan.
Clearing was found in northern IL and southern WI, while higher
clouds within the flow aloft were found over the Great Plains.

Little overall change is expected overnight to the ongoing forecast.
Models suggest lower level moisture lingering across the area. Some
clearing will be possible late, but the combination of high cloud
arriving along with a few scattered lake clouds should keep skies
mostly cloudy. Given our dew points in the teens and lower 20s. Low
mainly around 20 will be expected. Lows could reach the middle teens
in the LAF should some brief clearing occur.

&&

.SHORT TERM (This evening through Monday night)...
Issued at 301 PM EST Sun Nov 30 2025

Yesterday`s low pressure system is now departing to our northeast,
leaving cold temperatures, low clouds, and gusty winds in its wake.
Some flurries have been noted at times across the northern half of
our CWA. This may continue into the evening hours as winds shift
more northerly. In fact, some higher resolution guidance shows some
lake-enhanced showers making as far south as Kokomo/Muncie. However,
winds are expected to diminish quickly this evening as surface high
pressure moves in. This will limit southward extent of any snow
shower activity.

Despite surface high pressure, low-level cloud cover is expected to
hold firm through a majority of the night. Guidance hints at some
clearing, especially north and west, before sunrise. Combined with
the snowpack and light winds, ideal radiative cooling conditions
could briefly occur. Should enough clearing materialize, rapid
cooling may lead to temps even lower than what the forecast
currently indicates. It`s not out of the question that a few
readings into the single digits could occur if this happens. It is a
low-probability scenario but worth mentioning.

Snowfall Potential Monday Night

Our attention then turns to a system/vort max out west, roughly over
Salt Lake City as of this writing. Guidance shows this vort max
ejecting eastward tonight. Mid to high-level cloud cover quickly
increases ahead of it, so much of the day Monday will be cloudy.
Concurrently, a subtle wave in the subtropical jet will lift
northward tonight. These two systems begin to interact as they
approach Indiana Monday evening. Our weather Monday into Tuesday
depends on the degree of interaction, should it occur.

Thermal profiles show a cold enough air mass for all snow, at least
in our CWA. Snow totals are tricky, because as mentioned above they
are dependent on how the system comes together. A few scenarios will
be discussed below:

Most Likely Scenario...

We`ll start with what`s most probable. In this scenario a positively-
tilted vort max ejects from the Rockies before interacting with the
weak southern stream wave. Phasing occurs, but slow enough to keep
precipitation amounts relatively light. Total QPF between 0.10-0.25"
would be reasonable, which would lead to 1 to 3 inches of snow on
average assuming a 10:1 ratio. We will tend towards this scenario,
for now, as the progressive fast-moving pattern favors delayed
phasing.

Low-End Scenario...

Here, the southern wave is suppressed and phasing does not occur
until well after it matters. Moisture associated with the southern
wave does not come northward, leaving two disjointed areas of
precipitation. Precipitation over Indiana would be associated mainly
with the northern vort max, leaving lesser amounts across our south.
Most of our CWA would see a dusting to an inch, with perhaps an area
of 1-3 inches across our northwest depending on where the northern
wave tracks.

High-End Scenario...

In this scenario, phasing does occur and soon enough to allow for a
more potent vort max. Moisture associated with the southern wave is
readily lifted northward, allowing for precipitation to break out
over southern Illinois and into Indiana. Additionally, mid-level
frontogenesis could be more apparent which may lead to some heavier
banded snowfall. Snow bands would align with the thermal gradient,
roughly WSW-ENE, which is parallel to the system`s overall movement.
Such bands could effectively train over one location, leading to
isolated heavy snowfall amounts between 4-6 inches. Locations
outside of such bands would see less, generally 2-4 inches. Again,
this is a low-probability reasonable worst-case-scenario, and is not
the official forecast. However, it is worth mentioning these
possibilities as guidance has yet to form a solid consensus.

&&

.LONG TERM (Tuesday through Sunday)...
Issued at 301 PM EST Sun Nov 30 2025

A typical La Nina longwave pattern will continue across the
continent through the extended with upper ridging off the CA coast.
While an upper level low remains nearly centered over Hudson Bay
with longwave troughing extending southward from this low into much
of the central and eastern CONUS. Behind the shortwave trough that
will move through the region on Monday night precipitation ends
abruptly from the west with only low pops possible before 18Z
Tuesday in far eastern zones.

Attention turns to a shortwave trough moving southeast from the
northern plains into the region Wednesday into Wednesday night. Weak
to moderate WAA in the surface-700mb layer associated with sw flow
ahead of this trough will lead to a gradual moistening in the lower
to mid levels Wednesday afternoon into Wednesday evening. Have opted
to carry low pops in the northern half of the forecast area closer
to the greater DCVA and upper jet dynamics/phasing will exist. In
the wake of this system a reinforcing shot of arctic air settles
into the region Wednesday night. Temperatures will bottom out below
10F in northern portions of the forecast area with partly cloudy
skies and relatively deep snow pack. Partly cloudy skies will
continue through Thursday. Have raised low temperatures 5-10 deg
above NBM numbers for Thursday night thanks to increasing high-mid
level cloud cover ahead of another shortwave trough moving out of
the plains.

Models diverge on the extent of the late week (Friday) storm system
with some (Euro/Canadian) hinting at another low end advisory type
snow event possible. However, enough uncertainty exists with the
phasing of the moisture with the speed of the system to preclude
anything more than chance pops at this time. In addition, some
signal exists for a warm nose/mix precip event with freezing rain
and/or sleet possible in southern/central portions of the forecast
area. In the wake of the Fri system, low pops continue into Sunday
with glancing blows of weak shortwaves moving through the Great
Lakes region. Subtle hints at freezing drizzle/mix precip continue
so have opted to continue this in the forecast.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1206 AM EST Mon Dec 1 2025

Impacts:

- MVFR cigs possible at times through the day, mainly at KLAF.
- IFR and worse move in after 00Z Tuesday in snow.

Discussion:

Patchy MVFR ceilings will linger through the day today, but will
trend toward a more positive forecast based on regional observations
and trends in guidance. KLAF looks to have the best chances for MVFR
based on current trends, and will have to watch for some patchy fog
developing in the predawn hours if skies clear enough there.

Otherwise, conditions will deteriorate later Monday afternoon into
Monday evening, with IFR arriving after 00Z as snow moves into the
area. Snow will continue into early Tuesday morning.

&&

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

$$

UPDATE...Puma
SHORT TERM...Eckhoff
LONG TERM...Crosbie
AVIATION...50