622
FXUS63 KIND 160528
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
128 AM EDT Sun Aug 16 2026

.KEY MESSAGES...

- Strong to severe storms with damaging winds, heavy rainfall, and
  flash flooding remain a significant threat through the weekend

- Heat index values in excess of 100 possible today and Sunday in
  southern portions of central Indiana

- Dry and milder weather early in the work week

- Additional storms possible Wednesday

&&

.FORECAST UPDATE...
Issued at 1019 PM EDT Sat Aug 15 2026

Only minor changes to the timing of Sunday`s precipitation chances
with this update. A few isolated showers have persisted across
east- central Indiana this evening in the wake of a warm front.
To the west, water vapor imagery nicely shows a mid- level
shortwave trough axis shifting east out of Iowa into western
Illinois. Indeed, a cluster of storms has developed in the
vicinity of the attendant low. This system will provide the next
round of more widespread rain chances as it approaches the
forecast area by early morning. CAMs continue to vary in the
location of the heaviest rainfall, but given the abundant
moisture, increasing synoptic-scale lift, and a strengthening 850
mb jet, locally heavy rainfall will be possible--including over
areas that have already experienced flooding. The system
continues to look fairly progressive, however, which should limit
the time any stronger storm lingers over one location.

&&

.DISCUSSION (This evening through Saturday)...
Issued at 330 PM EDT Sat Aug 15 2026

Through 7PM:

Convection across the area has decreased significantly over the
course of the morning, with only a few isolated showers remaining
early this afternoon. Breaks in the cloudcover are evident on
visible satellite, which will allow for better destabilization of
the airmass as we head into the peak of daytime heating. Convective
inhibition has settled in across roughly the central third of the
state due to the extensive cold pool formed by this morning`s
activity. We will continue to see little to no precipitation for
the remainder of the afternoon. Cloud breaks, a lull in
precipitation, and SSW flow will allow afternoon high temperatures
to reach the low 80s in the north and low 90s in the south. Heat
Index values will approach and could exceed 100 in the southern
portion of the area where precipitation and cloud cover has been
more minimal, and a Heat Advisory is in effect for this region
through tomorrow afternoon.

Flash Flood warnings currently in effect across central Indiana will
be coming to an end as the precipitation has ended for the time
being. They will be transitioned to areal Flood Warnings to reflect
the lingering flood threat brought on by the several-days long
stretch of rain the area has seen this week. A Flood Watch is still
in effect through Sunday morning (at this time - future evaluations
may necessitate its extension) from Vigo/Clay/Owen/Decatur counties
and north.

7PM to Midnight:

A warm front draped across the southern portion of the CWA is
expected to lift northward tonight, bringing a more unstable airmass
back into the area. Initially, this front is not expected to trigger
much precipitation. Most CAMs keep any development during this time
period north/east of the IND CWA (NE IN/NW OH) where more robust
shortwave energy and upper-level support will be moving through. The
most likely area to see isolated shower/storm activity would be the
N/NErn border (Carroll-Howard-Delaware-Randolph area).

Midnight through Sunday morning:

Unfortunately, the heavy rain threat continues Sunday morning, as a
low-level jet begins to ramp up across central Missouri and Illinois
and push into the west once again. The warm front that moves north
into the area Saturday night precedes a low that will be pushed
in from the west Sunday, bringing yet another round of lift
through an extremely unstable and incredibly moist warm sector.
More widespread rain looks to start moving in to the northwestern
portion of the area after midnight.

Sunday and Sunday Night:

Despite precipitation activity throughout the morning, instability
is expected to soar into the afternoon hours, and sufficient bulk
shear 30+ kts may allow for a few supercells. The primary convective
hazard with this activity would be damaging winds with any line
segments that may form as progressive outflow boundaries collide and
roll through the volatile environment. However, flooding remains the
biggest concern. This system should be decently progressive, but it
will track directly over the same areas already experiencing
saturated soils. It will take very little to result in more flooding
Sunday afternoon. Rain comes to an end Sunday evening.

The warm sector keeps things nice and toasty, with high temperatures
Sunday consistent with Saturday along with Heat Index values near
and exceeding 100 in the south once again.

Monday/Tuesday:

Rejoice! Surface and mid-level ridging will keep the shortwave
energy at bay for a day or two and turn off the atmospheric hose.
Temperatures also drop back closer to normal, with highs in the
upper 70s to mid-80s. Clouds will clear out and we will enjoy a
couple days of sunshine, as well as a light north wind.

Wednesday/Thursday:

Savor the dry time while you can, as upper-level northwest flow
strikes again on Wednesday. Long term models show many pockets of
shortwave energy preceding a deeper wave that sweeps across the
Plains later in the day. The SPC has not indicated a severe risk
this far in advance due to the low level of predictability at
such a lead time, however it is safe to say that a flooding risk
will definitely return as there will not be enough dry time to
counteract the extended period of rainfall we have seen this week.

Friday and Beyond:

Long term models are not indicating much of a change from this
troughing pattern through the weekend, though some weak surface high
pressure and perhaps brief mid-level inverted ridging may be enough
to interrupt the rain chances for at least the end of the weekend
headed into next week. As mentioned, the primary threat with any
activity for the immediate forecast period will be flooding with
additional rainfall.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 128 AM EDT Sun Aug 16 2026

Impacts:

- Threat for showers and storms again at times through mid afternoon

- Patchy MVFR fog at some sites through daybreak

Discussion:

The continued presence of a very moist and humid airmass will
promote patchy MVFR fog through daybreak at one or more of the
outlying sites.

Additionally, isolated to widely scattered showers and storms are
developing near IND, and additional activity will likely move into
the area later this morning into the early to mid afternoon hours.
Will carry showers and PROB30 groups at each site during the most
favored time frame.

Winds will generally be light and variable to calm overnight,
becoming more westerly with time as high as 8-12KT.

&&

.IND WATCHES/WARNINGS/ADVISORIES...

Flood Watch until noon EDT today for INZ021-028>031-035>049-
051>057-065.

Heat Advisory until 8 PM EDT this evening for INZ060>063-067>071.

&&

$$

UPDATE...Didio/WFO SGF
AVIATION...Nield
DISCUSSION...Nelson/WFO SGF