304
FXUS63 KIND 030504
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
104 AM EDT Thu Sep 3 2026

.KEY MESSAGES...

- Heat Advisory in effect for all of central Indiana through late
  Friday...peak afternoon heat index values up to 108 degrees

- 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 (06Z TAF Issuance)...
Issued at 102 AM EDT Thu Sep 3 2026

Impacts:

- Low chances of MVFR visibility in fog/BR late tonight, mainly KLAF
- West-southwest gusts Thursday afternoon up to 12-15KT

Discussion:

Excepting low chances of brief MVFR visibility in fog towards dawn,
VFR conditions are expected to prevail across central Indiana
through Thursday night.  Stacked ridge prevailing over much of CONUS
will build northward through the Plains into tonight...directing
northern convection through the latter half of the 24/30-hour TAF
period from the Upper Midwest towards Ohio.  Recent forecast trends
have lowered chances in southern extent of these storms reaching
KLAF/KIND through at least 12Z Friday.

Otherwise occasional cirrus will oversee very warm/humid conditions
that will again promote FEW/SCT cumulus this afternoon.  Light and
mainly variable winds through 14Z will yield to another day of
southwest flow that should veer slightly to west-souhwest by late
day. A few higher gusts should reach 14-15KT at KIND/KLAF this
afternoon.

&&

.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