631
FXUS63 KIND 030159
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
959 PM EDT Wed Sep 2 2026

.KEY MESSAGES...

- Heat Advisory in effect for all of central Indiana through
  Friday evening with peak heat index values up to 108 are
  possible each afternoon

- Isolated to scattered thunderstorms will be possible at times
  late this week through the weekend.

&&

.FORECAST UPDATE...
Issued at 959 PM EDT Wed Sep 2 2026

Persistent unseasonably warm/hot pattern under broad stacked ridge
over most of the CONUS` eastern two-thirds...will maintain another
rain-free yet humid overnight with light southwest flow becoming
variable by pre-dawn hours.  Patchy fog will be possible towards
dawn amid elevated dewpoints, but impactful visibility reductions
are not expected.  Temperatures generally in the low to mid-80s as
0f 930 PM EDT will slowly fall to 72-76 by early Thursday.

&&

.DISCUSSION (This evening through Wednesday)...
Issued at 254 PM EDT Wed Sep 2 2026

Strong mid/upper-level ridging over the CONUS remains in place
through the end of the week, amplifying over the Plains this
weekend. With the main ridge axis amplifying to our west, troughing
over the northeastern US may nudge southwestward into Indiana late
Saturday or Sunday. This could allow for a backdoor cold front out
of the northeast, bringing an end to the current heat wave. The
reprieve may not last long as ensemble guidance hints at the ridge
building back eastward next week with above-average temperatures
returning to the region.

In the meantime, heat and humidity continue to build over the Ohio
River Valley. Temperatures have risen into the mid 90s with dew
points in the low 70s. ACARS soundings out of IND show around 1500
J/Kg MLCAPE with guidance showing an increase to around 2500 J/Kg
later this afternoon. The IND soundings also show a fairly deep but
modest cap around 700mb. The profile overall is rather dry as well.
Nevertheless, CAM guidance hints at some isolated convective
development later today into the early evening. Forcing seems
nebulous at best, and initiation will likely depend on subtle
features such as horizontal convective rolls. Severe potential
appears low, but with such a dry profile amid relatively steep lapse
rates, a downburst capable of strong winds cannot be ruled out.
Overall, chances of any one location experiencing convection today
is low and severe convection even lower.

Thursday is similar to today with heat, humidity, and
afternoon/evening storm chances. Thunderstorm potential looks to be
a bit better than today due to influence from upstream convection
(remnant outflow). The greatest potential exists across our northern
CWA, and especially into northern Indiana. Depending on how upstream
convection evolves overnight which determines the position of the
outflow boundary, subsequent development may not even reach central
Indiana. Isolated convection is also possible further south but
chances are low. Severe potential exists in the form of strong wind
gusts due to steep low-level lapse rates and high DCAPE (over 1000
K/Kg). Like today, overall chances are still low and severe
potential even lower.

By Friday, the amplifying ridge to our west will allow upper flow to
become more northerly. Guidance shows northeasterly surface flow
over Ohio pushing a thermal gradient southwestward towards Indiana.
Upstream convection may tend to ride along this gradient within the
northerly flow aloft. Low-level flow over Indiana is out of the west-
southwest at the time, which may encourage some west/southwestward
propagation. Like with any potential late summer MCS, strong winds
and flooding are the primary hazards. Activity may linger into
Saturday morning, depending on how far upstream and how late it
forms.

The thermal gradient then advances southwestward as a backdoor cold
front on Saturday allowing temperatures to return to near average
this weekend, perhaps even a bit below average.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 739 PM EDT Wed Sep 2 2026

Impacts:

- Low chances of MVFR visibility in fog/BR late tonight, mainly KLAF
- West-southwest gusts Thursday afternoon up to 13-17KT
- VCSH possible at KLAF after 21Z Wednesday

Discussion:

VFR conditions to generally prevail near central Indiana terminals
through early Thursday evening as broad, stacked subtropical ridge
continues to drift east over much of the CONUS.  Overall conditions
a near carbon-copy of preceding 24 hours, so have added TEMPO for
MVFR/ VFR fog at KLAF 08Z-12Z Thursday and noted slightly higher
gusts for Thursday afternoon where 15-17KT gusts will be possible at
times for at least KIND/KLAF.

Otherwise expect occasional cirrus and perhaps a bit better coverage
of afternoon cumulus Thursday.  Isolated convective showers are
possible late in the 24/30-hour period, mainly at KIND/KLAF, but
confidence too low to include in TAFs at this time.  Light southwest
winds to become variable by late tonight...with slight overall veer
in heading for Thursday to mainly 230-260 degrees, often sustained
near 10KT at KIND and near 7KT elsewhere.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT Friday for INZ021-028>031-035>049-
051>057-060>065-067>072.

&&

$$

UPDATE...AGM
AVIATION...AGM
DISCUSSION...Eckhoff