483
FXUS63 KIND 161323
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
923 AM EDT Wed Sep 16 2026

.KEY MESSAGES...

- Hot temperatures will continue at times into Saturday, especially
  south. Heat indices around 100 again today and Thursday.

- Scattered showers and storms today, but severe storms are not
  expected

- Shower and storm chances persist for much of the time into
  next week, with temperatures turning cooler next week

&&

.FORECAST UPDATE...
Issued at 923 AM EDT Wed Sep 16 2026

A mid to low level trough with a weak low level jet is passing
through the region today. Moisture advection within this LLJ is
allowing more weakly forced convection and numerous showers with
embedded thunder over the northern to mid Wabash Valley. This will
continue to push E/NE throughout the morning with most of the I-69
corridor and points to the NW getting rainfall.

The residual airmass across the region will be rather unstable this
afternoon and evening as convective temperatures are reached. The
primary forcing is likely to be old outflow boundaries, of which
will be the main area focus for additional convection later today.
Generally speaking, the main hazards for this afternoon remains
heavy rainfall and lightning, but a few cores may be large enough
for an isolated damaging wind threat.

&&

.DISCUSSION (Today through Tuesday)...
Issued at 252 AM EDT Wed Sep 16 2026

Early This Morning...

Energy riding around an upper high with help from a surface front
has been generating convection from northern Missouri into the
northern forecast area. Looking upstream, there may be a brief lull
as convection remains just west and north of the area, but more will
move in closer to sunrise. Outflow from the convection has reached
the I-70 corridor, and this may spark an isolated shower in that
area. Will continue with mainly chance PoPs from about I-70 north
through 12Z.

Some gusty winds and heavy rain are possible, but odds of severe
remain low given lessening instability.

Today...

Some stronger upper energy looks to bring showers and some storms to
portions of the northern forecast area after 12Z, so will go with
high chance to likely category PoPs there. Will keep chance PoPs
south of this area this morning in case outflow is enough to trigger
more isolated to scattered convection.

There looks to be less upper support this afternoon for convection,
but with various old outflows in the area as well as the surface
front, will go with at least slight chance PoPs most areas this
afternoon. The far southern area may be far enough from outflow and
close enough to the upper high to remain dry. Severe parameters look
low enough that severe storms are not expected, but a gusty storm is
possible. Locally heavy rain will remain a threat with a moist
atmosphere.

Convection/clouds will help keep temperatures cooler across the
northern forecast area, so went middle to upper 80s. The central
forecast area looks more uncertain thanks to the questions about how
much convection will be generated by outflows and the surface front.
Will go lower 90s there. The south should still be able to reach the
middle 90s. Heat indices will reach around 100 again this afternoon
for much of the area.

Tonight and Thursday...

More energy riding around the slowly retreating upper high along
with the old surface front will keep chances for convection around,
mainly across the northern half of the area. Similar to today,
clouds/convection Thursday will keep temperatures cooler north with
hot conditions persisting south. Heat indices will remain around 100
south during Thursday afternoon.

Friday and beyond...

The upper high will continue to gradually retreat southwest. The
surface front will sink far enough south initially to keep PoPs low
on Friday, but it will return north again on Saturday as an upper
wave interacts with the front. This will bring more rain chances,
mainly north.

After a brief reprieve from heat for many areas Friday, hot
conditions return on Saturday as the front moves back north.

Sunday into next week, larger upper waves moving through will keep
chances for rain around. Cooler air will filter back into the area,
with highs by Tuesday in the upper 70s to middle 80s.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 638 AM EDT Wed Sep 16 2026

Impacts:

- Convection will be around this morning, mainly at KLAF
- Additional isolated to scattered convection possible this
  afternoon
- Variable winds at times
- MVFR possible at KLAF overnight tonight

Discussion:

Convection will continue to impact KLAF at times this morning as
additional convection moves in from Illinois. Additional convection
may develop from outflow out of these storms, which may be reach
KHUF or KIND. However, confidence is low, so only used a VCSH for
those.

This afternoon, more scattered convection may develop along old
outflows and near a weak front across the area. Confidence is too
low in details for anything other than a VCSH mention.

The presence of multiple outflow boundaries and the front will lead
to variable winds at times today. Behind the front, MVFR ceilings
and visibility may develop at KLAF overnight.


&&

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

$$

UPDATE...Updike
AVIATION...50
DISCUSSION...50