246
FXUS63 KIND 210515
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1215 AM EST Fri Nov 21 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

&&

.FORECAST UPDATE...
Issued at 921 PM EST Thu Nov 20 2025

Main concern overnight will be the potential for fog development.
This is primarily expected to occur north of I-70 where some mid
level subsidence should push the stratus layer towards the surface.
The more uncertain caveat will be just how dense this fog will get.
Most areas north of I-70 should fall beneath 2SM, but there could be
a corridor with dense fog (1/2SM or less). Currently this is
expected over the upper Wabash Valley, but trends will have to be
watched closely for points east of this region.

South of I-70, onset of rainshowers has been mostly delayed until
the morning hours outstay of some isolated chances along a push of
isentropic lift between 04-08Z.

&&

.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 (06Z TAF Issuance)...
Issued at 1216 AM EST Fri Nov 21 2025

Impacts:

- Widespread IFR/LIFR conditions through tonight
- Rain overspreading the terminals predawn hours through the morning

Discussion:

Very poor flying conditions will continue through the duration of
the forecast period as moisture remain trapped in the near surface
layer beneath an inversion. Ceilings hovering early this morning at
or below 500ft and expect that to continue along with the expansion
of dense fog at times through and beyond daybreak. Rain will expand
into the region first reaching KHUF and KBMG in the predawn hours
then the other terminals through the morning.

Widespread rain is expected to last into tonight with the potential
for the heaviest rainfall at KBMG. The onset of rain should flush
out the dense fog and may help bump up ceilings slightly during the
day...but IFR and lower conditions will persist. Near calm winds
through daybreak will shift to E/NE at 5-7kts this afternoon.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM EST this morning for INZ021-
028>031-035>049.

&&

$$

UPDATE...Updike
SHORT TERM...Melo
LONG TERM...Eckhoff
AVIATION...Ryan