672
FXUS63 KIND 201950
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
250 PM EST Thu Nov 20 2025

.KEY MESSAGES...

- Fog development expected again tonight; greatest coverage across
  the north where there is increasing potential for dense fog

- Drizzle possible at times overnight with increasing coverage of
  showers late tonight into Friday

- Additional rainfall early next week with much cooler weather
  likely post-Thanksgiving

&&

.SHORT TERM (This evening through Friday)...
Issued at 249 PM EST Thu Nov 20 2025

Continued dreary conditions can be expected through the period as a
persistent subsidence inversion aloft and warm air advection beneath
it allows a low-level stratus deck to remain in place. Latest
observations show ceilings and visibilities have improved gradually
through the day as temperatures have slowly warmed. Unfortunately,
this improvement will only be short-lived as ceilings and
visibilities drop again overnight.

Latest guidance has trended drier overnight especially across the
northern half of the area. Forecast soundings show the subsidence
inversion strengthening over the north slightly with winds becoming
very light or even calm at times. This and very small dewpoint
depressions will quickly promote fog development into the overnight,
potentially dense. Patchy drizzle is also possible thanks to
marginal forcing. Guidance shows subsidence slowly increasing aloft
overnight across the south as well. However, greater PBL moisture
and slightly stronger forcing supports better chances for drizzle
and the development of light showers. The higher chances for light
precipitation over southern counties leads to lower confidence in
coverage or duration of fog overnight.

Model guidance depicts the aforementioned subsidence inversion
weakening with increasing isentropic ascent during the day Friday.
This will lead to greater coverage of showers as the day goes on.
Showers should help clear out fog through the morning. Cannot rule
out fog lingering through midday across the north if showers move in
later than expected. Blended guidance has been far too warm with the
stratus deck overhead which has limited the diurnal temperature
swing significantly. High temperatures today and tomorrow were
trended lower than the NBM. Look for lows to generally range from
the mid 40s to near 50F tonight while highs Friday mostly remain in
the low 50s.

&&

.LONG TERM (Friday night through Thursday)...
Issued at 249 PM EST Thu Nov 20 2025

Upper-level analysis shows a progressive split flow jet pattern over
the CONUS. Flow tends to split over the west coast before converging
again over the Midwest. This broad upper-level convergence, in
tandem with surface high pressure pushing southward, will lead to
broad subsidence Friday night into Saturday. Model trends have shown
this subsident atmosphere edging southward, and have shown less
rainfall compared to previous runs. We will trim PoPs a bit across
our north while maintaining likely to categorical PoPs from Indy
southward. We lowered total expected rainfall amounts as well,
especially further north. Further reductions may be needed.

The system responsible for Friday`s rain will depart eastward on
Saturday. Surface high pressure arrives along with a dry continental
polar air mass from the north. With a drying trend shown in guidance
it now appears likely that we`ll finally see some sunshine beginning
on Saturday. Clear to partly cloudy skies should then continue
through the weekend. Larger diurnal temperature swings are expected
due to clearing skies, with highs in the 50s/low 60s and lows in the
30s. Patchy overnight fog is possible at times this weekend due to
recent rainfall and ideal radiative cooling during the overnights.

Quiet weather continues into the new week, but is not expected to
last long. A storm system, currently over southern California, looks
to eject eastward out of the Rockies on Monday. Guidance shows this
system remaining quite weak while potentially merging with a system
moving eastward over the US/Canadian border. Guidances diverges at
this point, with various models handling the potential interaction
differently. Regardless, rain appears likely as the southern system
moves northeastward on Tuesday. How much rainfall and exact timing
will come down to how the interaction with the northern stream
evolves.

A trend towards colder weather appears increasingly likely late in
the week or next weekend. The aforementioned split flow pattern looks
to consolidate into a single stream with broad troughing over the
central and eastern US. Timing and magnitude of the initial push of
cold air may again depend on the interaction of the early-week storm
systems. A stronger resultant low may allow for a quicker/stronger
push of cold air southward, and vice versa.

Day 8-14: Taking a peek towards the end of the month / early
December. Ensemble guidance hints at continued troughing over the
northern US with repeated shots of arctic air (whether these make it
to Indiana is unknown as of now). Additionally, ensemble guidance
hints at troughing shifting westward which may allow for a more
active storm track over the Midwestern US.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1243 PM EST Thu Nov 20 2025

Impacts:

- Widespread IFR/LIFR conditions improving to low end MVFR later
  this afternoon at some sites

- Return to IFR this evening into tonight with LIFR conditions
  expected at most sites by late tonight

- Drizzle or light showers moving in tonight into Friday morning

Discussion:

Widespread low stratus and fog continue across the area with
IFR/LIFR conditions. Some light drizzle has been reported at times
as well.

Gradual improvement in ceilings and visibilities is expected over
the next few hours, with low end MVFR returning for a time this
afternoon into early evening, before deteriorating back to IFR and
eventually LIFR overnight. Some sites may not improve to MVFR
similar to yesterday so will continue to monitor this.

Drizzle or light showers will move in during the overnight hours
with conditions again deteriorating as previously mentioned. Areas
of fog are also expected, especially across the northern half of
central Indiana where precipitation will take longer to move in.


&&

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

$$

SHORT TERM...Melo
LONG TERM...Eckhoff
AVIATION...Melo