203
FXUS63 KIND 260239
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
939 PM EST Thu Dec 25 2025

.KEY MESSAGES...

- Areas of fog again tonight, dense fog expected to be brief and patchy

- Drizzle and light rain tonight and early tomorrow

- Warmer for the weekend, turning much colder late Sunday to Monday

&&

.FORECAST UPDATE...
Issued at 939 PM EST Thu Dec 25 2025

Very similar weather is expected tonight as the same warm front
lifts northward ahead of another wave. This warm front is currently
producing widespread dense fog over far SW portions of central
Indiana, where winds have calmed. This should eventually push
northward with the front, but dense fog will be possible through
09Z, highlighted by the advisory for this same period.

As the front lifts northward, additional periods of dense fog will
be likely over the rest of central Indiana, but will be much shorter
lived, and therefor is being handled with an SPS.Drizzle will be the
primary form of precipitation tonight, but isolated to scattered
showers will likely develop at times throughout central Indiana,
south of the low level disturbance.

&&

.SHORT TERM (This evening through Friday)...
Issued at 1251 PM EST Thu Dec 25 2025

Rest of Today and Tonight.

Main focus for the short term period will be tracking the
drizzle/light rain tonight and the potential for some additional
locally dense fog. The current synoptic setup features a stagnant
surface high pressure system centered over Ontario which continues
to bring northeasterly CAA into the region. This has trapped a deep
layer of low-level moisture beneath a potent subsidence inversion
above the 925mb level. Through the remainder of today, expect these
dreary conditions to persist with high confidence of thick cloud
cover remaining locked into place.  A stubborn area of dense fog has
persisted through the morning near Vincennes where winds remain
calm, but expect this to improve by 2-3PM as temperatures slowly
warm.

Heading into tonight, a subtle mid-level shortwave currently
traversing the Mid-Mississippi Valley will track toward the Ohio
Valley. This feature will renew isentropic lift across the region,
bringing a return in light rain and drizzle. As the surface flow
begins to veer in response to the approaching wave, another round of
patchy dense fog is likely, especially for areas south of I-70 where
low-level saturation is most pronounced. The warm front that has
been draped across the Ohio Valley over the last couple of days is
expected to move northeastward tonight with fog coverage expected to
be greatest right along the front where winds will be near calm.
This will help to keep the duration of denser fog brief enough to
not warrant a Dense Fog Advisory at this time.

Friday.

A significant pattern shift arrives by Friday morning as the
aforementioned warm front continues to surge northward helping to
scour out the low-level moisture and breaking the stubborn
temperature inversion. As a result, clouds will finally scatter out
from south to north by Friday afternoon. With a strengthening
southwesterly breeze gusting up to 20 mph and the arrival of
sunshine, temperatures will soar into the low-to-mid 60s. Forecast
highs on Friday are within a few degrees of the record for
Indianapolis, providing a spring-like end to the short-term period.

&&

.LONG TERM (Friday night through Thursday)...
Issued at 1251 PM EST Thu Dec 25 2025

Friday Night Through Through Monday.

The unseasonably mild regime will peak through the first half of the
weekend as a robust upper level ridge moves over the Ohio Valley.
Saturday is expected to be the warmest day of the week, with deep-
layer southwesterly flow and mostly sunny skies allowing highs to
reach the mid-to-upper 60s. Low level thermal profiles are expected
to be 2-3 standard deviations above climatological norms, keeping
even overnight lows in the 50s. However, this amplified pattern is a
precursor to a major synoptic transition. A deep, positively-tilted
trough will begin to dig into the Central Plains Saturday night,
sharpening a cold frontal zone that will stretch from Hudson Bay
down through the Mid-Mississippi Valley. Rain chances will increase
rapidly early Sunday as the front approaches, supported by a potent
low-level jet advecting Gulf moisture into the region. Widespread
rain showers are expected throughout Sunday, with total rainfall
amounts likely ranging between 0.50 and 0.75 inches. A few rumbles
of thunder and some gusty winds will be possible during the
afternoon and evening hours with this system, but severe weather
looks unlikely at this time.

The transition to much colder temperatures occurs Sunday night into
early Monday morning as the cold front sweeps through. Models show a
dramatic 40 degree temperature drop in roughly 12 hours in the
aftermath of the frontal passage. While the bulk of the moisture
will exit before the deepest cold air arrives, a brief period of
rain changing to light snow is possible. Accumulations should be
minimal given the antecedent warm ground, but the rapid freeze-up of
residual moisture on roadway could produce a flash freeze in
surfaces that have remaining standing water. There will be enough
drying time and stronger winds to limit the overall impacts.

Tuesday through Thursday.

Winter returns in earnest as a 1040mb Canadian high pressure system
dominates the eastern two-thirds of the US. High temperatures
through the final days of 2025 will be held in the 20s and low 30s.
Tight pressure gradients on Monday will result in blustery northwest
winds gusting 25-35 mph, driving wind chill values into the single
digits. While generally dry conditions will prevail mid-week under
the influence of the polar high, some lake effect cloudiness and
stray flurries may impact the northern counties. The year looks to
end on a frigid but quiet note, with clear skies and light winds for
New Year`s Eve allowing temperatures to drop into the teens.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 605 PM EST Thu Dec 25 2025

Impacts:

- LIFR to IFR cigs through much of the TAF period
- MVFR to IFR vsbys again tonight
- Light rain and drizzle tonight

Discussion:

LIFR to IFR cigs are currently present across central Indiana with
some lifting of cloud bases expected through the evening. Any brief
MVFR to VFR conditions will return to a combination of IFR to LIFR
after 00Z with persistent low level moisture. Non-dense fog is
expected through the afternoon becoming more transient through the
evening. A brief period of dense fog will be possible tonight,
mainly at HUF and BMG with vsbys generally closer to a mile
elsewhere at times. Light rain and drizzle will also occasionally
help to lower vsbys beyond the fog. Winds are expected to remain
northeasterly to easterly at 4-10kts through the TAF period.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 4 AM EST Friday for INZ060-061-067>069.

&&

$$

UPDATE...Updike
SHORT TERM...White
LONG TERM...White
AVIATION...Updike