Lafayette, Indiana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

641
FXUS63 KIND 232034
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
334 PM EST Fri Jan 23 2026

.KEY MESSAGES...

- A COLD WEATHER ADVISORY is in effect along and north of a Terre
  Haute to Muncie Line from through 10AM EST Saturday.

- Near zero or subzero lows possible tonight along with
  potentially dangerous wind chills at or below
  -10F.

- Winter Storm Warning for central Indiana Saturday at noon
  through Monday morning

- Total snowfall amounts as high as 12 inches with high
  confidence in 6+ for the I-70 corridor and points to the south

&&

.Discussion (This evening through Wednesday)... Issued at 331 PM
EST Fri Jan 23 2026

Strong surface high pressure is building southeast behind an Arctic
cold front that passed through last night. Temperatures have been
fairly steady in the high single digits to near 10 degrees this
afternoon, despite diffuse sunshine. The Arctic air mass is expected
to remain in place through the weekend with highs in the 10s and
lows in single digits to near zero.

Further upstream, a closed mid/upper-level low off the coast of
southern California is beginning to move eastward. Northward
moisture return has commenced across the southern Plains as upper-
level forcing increases. This is the first sign of the upcoming
system that will bring wintry weather to much of the nation east of
the Rockies.

THIS WEEKEND

The mid/upper-low is not the only player in this story. Another
shortwave trough diving southward out of western Canada is modeled
to interact with this system over the southern Plains. To complicate
matters further, a third shortwave is also expected to enter the
picture and interact with the developing storm. This complicated
phasing situation has been a source of uncertainty within guidance
over the past several days. Upstream phasing typically leads to a
northward trend within guidance and that is what has occurred. That
trend has slowed, however, as guidance has a better handle on the
situation now that the pieces are all on the board. Still, some
uncertainty remains as models still have some time before they get
better data ingestion of the aforementioned waves as the reach the
CONUS. This should improve the modeled phasing process as its
current depiction looks slow and kind of messy.

The resulting mid/upper-level system does not phase in the classic
sense, either. Instead of a wrapped-up "bowling ball" upper low, we
get a positively-tilted and increasingly stretched trough that races
northeastward. This setup typically doesn`t lead to a potent surface
low that rapidly develops while undergoing the occlusion process. In
fact, most guidance now shows a rather weak low attempting to lift
northeast along the spine of the Appalachians before transitioning to
the east coast.

Without a wrapped up mature low, a fully developed warm conveyor
does not appear likely. This is best seen in recent trends of the
NAM, which has recently lost the "comma head" appearance in its
precipitation field. So what does this mean in terms of forcing?
Forcing will come primarily through jet dynamics rather than strong
frontogenesis and mesoscale processes. This should lead to a broader
forced snowfall with moderate QPF rates throughout late Saturday
night until late Sunday afternoon. Thus, rates are not expected to
be that overwhelming with rates between 0.5" to 1.0" per hour a
majority of the time, and our storm total exceeding warning criteria
mostly due to longevity of snowfall versus very heavy snow rates.
This all said, our position relative to the entry and exit regions
of the overhead jet stream is ideal, especially during the morning
on Sunday; with added lift within strong positive vorticity
advection, rates at times Sunday morning could be heavy at
times. (More on this in the next section)

SNOWFALL TOTALS

Expected snowfall comes down to duration and snow liquid ratios
(SLRs). Given the positively tilted and rather elongated nature of
the parent trough, a long duration event is anticipated. Snow may
continue more or less continuously for over 24 hours. So, even light
snowfall should pile up over time. As for SLRs, model soundings show
deep moisture through the dendritic growth zone (DGZ) initially,
before some mid-level warm advection allows temperatures to climb
out of that zone for a bit. Still, the best forcing appears to
remain within the DGZ (between 700 and 500mb), as upper-level jet
dynamics remain the primary source of forcing. Therefore, an average
SLR of around 12:1 to 14:1 should be common across central Indiana.

With a model average of between 0.25 inches (north) and nearly 1.0
inches (south) of liquid, we can apply the SLR described above to
generate a forecast range of 5 inches (north) to 12 inches (south)
of snow. The Indianapolis metro is roughly in the middle with around
6-10 inches.

If snowfall totals ultimately trend toward the lower end of the
current projections, it will likely be due to one or a combination
of several factors. The first of which  is the presence of abundant
antecedent dry air prior to snowfall onset on Saturday. Considerable
time may be required to sufficiently erode this dry layer and
depending on the timing and degree of initial system phasing,
snowfall amounts through Saturday evening could be below 2 inches
(before greater snowfall on Sunday).

The other contributing factor to the potential for a low end
scenario is the possibility for lower SLRS than current projections.
While model guidance continues to indicate periods of synoptic-scale
ascent extending through the DGZ, this forcing is expected to be
relatively broad and weak. Such a setup may result in reduced
residence time of ice crystals within the DGZ, thereby limiting snow
growth efficiency. Additionally, the prolonged duration of
snowfall may promote compaction, further reducing SLRs compared to
a more intense, shorter duration accumulation period.

Also of note, far NW portions of central Indiana may see some dry
air entrainment. This along with potential phasing issues later on
Sunday has lead to greater uncertainty on the northern edge of the
snowfall area, roughly from Lafayette to Kokomo and areas northward.

NEXT WEEK

Once the snow exits on Monday we`ll see continued cold with little
respite. Ensembles are in excellent agreement showing predominant
troughing over the eastern US with below normal temperatures. Global
teleconnections add weight to this consensus, with a strongly
negative Arctic Oscillation (AO) and positive Pacific North American
pattern (PNA). With a snowpack in place, daily highs may struggle to
reach 20 with lows near or even below zero each night this week.


&&

.AVIATION (18Z TAF Issuance)...
Issued at 1231 PM EST Fri Jan 23 2026

Impacts:

- NNW wind gusts near 20kt today
- MVFR ceilings/visibility arrive Saturday with snow

Discussion:

Brisk northwesterly flow continues behind this morning`s cold front
with occasional gusts up to 20kt. Winds are expected to diminish
somewhat, remaining near 10kt however. Wind direction slowly becomes
northeasterly through the night into the day Saturday.

Mid to high-level cloud cover has gradually increased through the
day today as a system develops over the southern Plains. Expect
clouds to continue increasing with lowering ceilings through the
night.

Guidance is in good agreement on light snow arriving in central
Indiana between 17-20z Saturday. Snow moves in from the southwest,
with HUF, IND, and BMG seeing snowfall arrive before the end of
their respective TAF periods. It may take a few more hours before
snow reaches LAF with the most likely start time occurring after 21z.

MVFR, or lower, ceilings/visibility are expected once the snow
begins and thereafter.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory until noon EST Saturday for INZ021-028>031-
035>049-051-052.

Winter Storm Warning from 7 PM Saturday to 7 AM EST Monday for
INZ021-028>031-035>042.

Winter Storm Warning from noon Saturday to 7 AM EST Monday for
INZ043>049-051>057-060>065-067>072.

Cold Weather Advisory from 7 PM this evening to noon EST
Saturday for INZ053>057-060>065-067>072.

&&

$$

Discussion...Eckhoff/Updike
AVIATION...Eckhoff