233
FXUS63 KIND 051302
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
902 AM EDT Sat Sep 5 2026

.KEY MESSAGES...

- Heat Advisory through this evening for all of central
  Indiana except the far NE

- Isolated to scattered thunderstorms will be possible at times
  through the day

&&

.FORECAST UPDATE...
Issued at 902 AM EDT Sat Sep 5 2026

Surface analysis this morning shows a meso high over SW OH due to
earlier convection. This high was pushing a gust front across
Central Indiana, and brining some relief regarding dew points. Dew
points across Central Indiana have fallen to mid 60s. Radar shows a
few isolated showers and storms still ahead of the gust front over
SW Indiana, but these were weakening. The meso high has resulted in
a bit more stable air mass across Central Indiana, however a new
boundary along the gust front is now in play. Water vapor imagery
shows ridging in place over the northern plains, with NW flow
spilling into Indiana from the upper midwest. Subsidence was shown
in place across Central Indiana.

The new air mass with lower dew points along with subsidence aloft
will help provide dry weather late this morning and early this
afternoon. However, by late afternoon, diurnal convection will be
possible as forecast soundings show CAPE in excess of 300 J/kg. Best
chances for showers and storm development will be across SW Indiana
where the lingering now boundary will be located and several of the
CAMS have noted this, placing best area for afternoon convection in
SW Indiana and near the Ohio River. Thus will keep the forecast dry
through mid afternoon, and add pops late this afternoon. Highs will
once again reach the low to mid 90s, producing heat index values in
excess of 100.

&&

.DISCUSSION (Today through Friday)...
Issued at 306 AM EDT Sat Sep 5 2026

Broad ridging centered over the Plains will amplify while slowly
drifting westward. This allows a trough over the northeastern US to
push into the Ohio River Valley, bringing an end to the current heat
wave. The ridge, temporarily shunted west, returns next week with
renewed heat and humidity. The secondary round of heat does not
appear to be as prolonged, with another trough arriving late next
week along with a reduction in temperatures. Scattered showers and
thunderstorms are possible with both troughs, though chances are
generally 40 percent or lower due to limited moisture and forcing.

Today will be another hot one for most of the forecast area
remaining in a heat advisory with max heat indices near to above
105. The troughing to the NE is expected to finally creep into the
area, which will likely keep highs below 90 degrees for our NE
counties. With the trough creeping in, there will be better chances
of showers and storms today and into this evening ahead of a
backdoor front that will bring a reprieve from the heat for the
start of the new week.

As of early this morning, the cold front is draped over northern
Indiana and into Ohio, along which a couple lines of thunderstorms
have formed. The question for central Indiana is if these storms
will reach the forecast area later this morning or if they will stay
just outside until later in the day. Also watching radar to see how
things play out along gust fronts surging south off of the
storms. Atmospheric moisture is modeled to increase today with
better lapse rates. With the front acting as an initiating force,
our convective chances are a lot better compared to the past
couple of days. Still, large-scale mid/upper-level forcing is
displaced to the northeast and thus the convective chances are
dependent on the front itself.

As mentioned above, still looking at a couple of existing scenarios.
First, the front initiates convection during the early to mid-
morning hours, which then propagates southwestward into the
southwesterly low-level flow ahead of the boundary. This would
generally limit severe potential with the primary hazard being heavy
rainfall and localized flooding.

Second, the front enters central Indiana dry allowing daytime
heating to maximize. Increased instability along the front would
help initiate convection during the afternoon, which would propagate
southeastward in line with the shear vector. Bulk shear is not
excessive, but enough to allow for some storm-scale organization
into clusters or small bowing segments. Steeper lapse rates and
residual dryness may present a downburst or wind threat.

Behind the long awaited cold front, which should arrive late
tonight, will bring cooler and drier air to the area. This airmass
will only last a few days before the ridging and heat returns for
midweek. Another frontal system should bring a relative dip in
temperatures again late week as well as another chance of showers
and storms sometime mid to late week.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 649 AM EDT Sat Sep 5 2026

Impacts:

- Scattered showers and storms today, mainly 18Z to 02Z
- Wind shift to northeasterly Saturday evening

Discussion:

VFR conditions expected through the TAF period outside of periods of
lowered vsbys during convection and brief patchy fog near LAF this
morning. Isolated convection may be around the area late tonight
towards LAF or IND towards daybreak this morning but more likely
VCSH to start. A gust front may also lead to a shift in wind
direction at IND at the start of the period. Additional scattered
convection is expected to develop during the afternoon and evening
hours with greater coverage compared to Friday. Winds will generally
remain westerly through late today before a cold front will shift
winds to the northeast towards tonight.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT this evening for INZ028>030-035>037-
039-043>048-051>057-060>065-067>072.

&&

$$

UPDATE...Puma
AVIATION...KF
DISCUSSION...KF/Eckhoff