518
FXUS63 KIND 251304
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
904 AM EDT Fri Sep 25 2026

.KEY MESSAGES...

- Clearing skies with a warming trend this weekend.

- Rain chances increase Tuesday night through Friday.

&&

.FORECAST UPDATE...
Issued at 901 AM EDT Fri Sep 25 2026

While very dry in the lowest 5KM of the troposphere, moisture is
quickly advecting into central Indiana above that dry layer leading
to rapidly increasing cloud cover over the state. ACARS soundings
show this cloud layer to be rather deep (around 1km in depth)
leading to a large decrease in downwelling solar radiation. Given
the depth of the low level dry layer, there will likely be some
mixing as we reach the afternoon, but overall diurnal gains will be
dampened significantly today. The combination of this and efficient
diurnal cooling last night will likely lead to highs not reaching
70 for most of the area, with some portions of NE central Indiana
only topping out in the mid 60s.

&&

.DISCUSSION (Today through Thursday)...
Issued at 301 AM EDT Fri Sep 25 2026

Surface high pressure is building southwestward into Indiana, which
has allowed stratus to diminish across the region. However, high
cirrus is increasing due to a system over the Great Plains. Though
this system remains to our west, high and eventually mid-level cloud
cover could become thick at times this afternoon and evening. A few
light rain showers cannot be ruled out either.

The upper-level pattern is blocked, with deep cut-off troughing over
the eastern seaboard. This will keep the system over the Plains to
our west, even causing it to retrograde somewhat. High pressure
continues to build westward bringing clearing skies late Friday into
the weekend. Patchy fog is possible at times Friday night and
Saturday night, with ideal radiative cooling potential expected.
Locally dense fog is possible as well.

Temperatures are expected to rebound towards normal values (low to
mid 70s), with lows being a bit cooler than normal (mid 50s). Expect
highs in the low to mid 70s with nightly lows in the upper 40s to
low 50s.

NEXT WEEK

Guidance has trended away from a strong, wrapped up mid latitude low
on Tuesday/Wednesday and more towards a weak wave passing to our
north. Cloud cover and precipitation chances still increase, but
strong thunderstorm potential has decreased. Ensembles have diverged
regarding the overall pattern late next week, with some models
showing a secondary wave developing Thursday or Friday. This wave
may interact with moisture from Hurricane Polo, currently off the
southern coast of Mexico. Given high model spread, forecast
confidence is low. PoPs will be capped at chance for a broad
timeframe...late Tuesday through Friday. This will be refined as
guidance comes into better agreement.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 637 AM EDT Fri Sep 25 2026

Impacts:

- None

Discussion:

Cirrus is beginning to stream in from the northwest from a larger-
scale system passing through the Plains. These clouds are expected
to increase in coverage this morning. Mid-level clouds then increase
during the day today, becoming BKN to OVC at times. An isolated
shower cannot be ruled out. Cloud cover begins to diminish after 12z
Saturday, with clear skies returning by late Saturday morning.

Winds retain an east-northeast component through the forecast
period, with light and variable conditions possible during the
overnight hours.


&&

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

$$

UPDATE...Updike
AVIATION...Eckhoff
DISCUSSION...Eckhoff