209
FXUS63 KIND 170648
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
248 AM EDT Thu Sep 17 2026

.KEY MESSAGES...

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

- 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

&&

.DISCUSSION (Today through Wednesday)...
Issued at 248 AM EDT Thu Sep 17 2026

Early This Morning...

Showers and thunderstorms have been near and across the far northern
forecast area early this morning. These are along a boundary,
with forcing from upper energy and 850mb winds helping generate the
storms. The upstream trend has been for the overall movement of the
storms to shift northeast. Thus, the general threat for heavy rain
has diminished for the northeast forecast area.

Will continue with some chance PoPs across the northern forecast
area.

Today...

Another piece of upper energy will likely generate another round of
convection north of central Indiana early, which will move southeast
and impact northern portions of the forecast area this morning. Will
go with likely PoPs across the extreme northern forecast area with
chance PoPs across much of the remainder of the northern area.

There remains some uncertainty on how large this area of storms will
be and how far south it will actually get, with latest HRRR trends
being farther north. The 00Z CAM runs keep the heaviest rain north
of central Indiana as well, so confidence in the Flood Watch
continues to diminish. However, am reluctant to cancel the watch
since a complex with heavy rain cannot be ruled out. After
collaboration with neighboring offices, will just pull the
southernmost county (Henry) out of the watch.

This area of storms will likely push the boundary farther southwest
into this afternoon. Not much upper support will be around for
convection, but can`t rule out isolated convection developing. Will
keep some slight chance PoPs for parts of the area.

Severe parameters indicate a very low threat for severe weather, but
gusty winds and heavy rain remain possible.

The morning rain and the boundary will keep a temperature gradient
across the area, with highs in the mid 80s northeast to mid 90s
southwest. Heat indices around 100 will be likely again across the
southwest.

Tonight and Friday...

Another round of upper energy interacting with the meandering
surface boundary will bring more scattered convection. Will go with
chance PoPs many areas. These will carry over into Friday morning
before forcing weakens.

The boundary will get pushed farther to the southwest, so by mid-
afternoon only the southwest half of the area will see any PoPs.
These will be low PoPs with little or no additional forcing around.

With the expected movement of the boundary, cooler air will get into
more of the area. Highs on Friday will range from around 80
northeast to the lower 90s southwest.

Saturday and beyond...

Upper and surface waves will cause the boundary to meander across
central Indiana into early next week. This will keep chances for
showers and thunderstorms around. Confidence on timing and location
of the highest PoPs remains low with uncertainties on exact
movements of the boundary.

Saturday`s highs will rebound as the boundary gets pushed northeast,
with lower and middle 90s southwest and mid and upper 80s northeast.
However, by Monday, the boundary will be far enough south for highs
in the mid 70s north to mid 80s south.

Additional upper waves will keep low chances for rain around mid-
week next week. Temperatures will be more seasonable with highs in
the 70s to lower 80s.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 131 AM EDT Thu Sep 17 2026

Impacts:

- Showers/isolated storms possible near KLAF early

- Additional convection may move across KLAF/KIND 12-18Z

- MVFR conditions likely developing at KLAF overnight. MVFR
  fog possible at KHUF overnight.

Discussion:

Convection near a boundary will continue just north of KLAF early in
the period, and cannot rule out a shower or storm sneaking into
KLAF. Another area of convection may move northwest to southeast
12-18Z and may impact KLAF/KIND. Additional isolated convection is
possible this afternoon at all sites, but odds are too low to
mention at this time.

The boundary will sink south early in the period and will likely
bring MVFR conditions to KLAF overnight into Thursday morning. These
will then mix out to VFR. MVFR fog is possible at KHUF overnight.

Will have to monitor for additional convection and MVFR conditions
after 04Z Friday.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 2 PM EDT this afternoon for INZ031-038-040>042.

&&

$$

AVIATION...50
DISCUSSION...50