137
FXUS63 KIND 150528
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
128 AM EDT Sat Aug 15 2026

.KEY MESSAGES...

- Heavy rain and localized flash flooding will be possible again
  late tonight and on Saturday morning.

- The additional rain may worsen an already significant flooding
  event.

- Additional storm chances on Sunday.

- Drier and cooler weather settles in Monday through early next week.

&&

.FORECAST UPDATE...
Issued at 1006 PM EDT Fri Aug 14 2026

A mostly quiet forecast is expected over the next few hours as
central Indiana remains within weak height rises ahead of an
approaching MCV over Illinois. The main point of uncertainty is a
weak quasi-warm frontal feature that is forming near a line from
Logansport to Richmond. If this feature is able to establish within
the increasing LLJ, scattered elevated convection cannot be ruled
out. Given rich moisture through the troposphere, any storm that
does for will have efficient rain rates and thus would pose a
flash flood risk, especially due to the low FFG over this area.
The current probability of occurrence of this is low, around 15
percent, but still is worthy enough to be monitored closely over
the next few hours.

&&

.DISCUSSION (This evening through Friday)...
Issued at 229 PM EDT Fri Aug 14 2026

Surface analysis this afternoon shows a trough of low pressure
stretched from Central IL across central Indiana and then east to
Dayton. GOES19 shows an extensive area clouds remnants from earlier
thunderstorms. Cloud tops continued to warm as showers for the most
part continued to dissipate. Radar still shows scattered showers
stretching from IA across IL to Central Indiana. Clouds had limited
daytime heating somewhat as most temperatures were in the 70s. Water
Vapor imagery shows ridging in place over the Mississippi Valley.
The ridge was allowing a tropical flow from the Pacific to stream up
and around it before reaching Indiana and the Ohio valley. An
embedded wave was found across IL and Indiana, pushing east within
the flow.

Tonight and Saturday...

Cloud cover across the area this afternoon is expected to remain
into the evening. This will prevent any additional diurnal
convection as convective temperatures will not be reached. None the
less, clouds will continue to linger through the evening and
overnight, along with the lower level boundary remaining in place.
Forecast soundings show plentiful moisture through the column
overnight, with high pwats still available. However a forcing
mechanism does not appear available much of the night. The HRRR
suggests another MCS pushing toward Indiana near 09Z and beginning
to cross the state at and around 12Z. Diurnal trends would suggest a
gradual dissipation through the morning hours. However, again
forecast soundings still show abundant moisture with high pwats
through the day.

Thus we will use low pops this evening, but will ramp pops higher
across the northern parts of the forecast area from late tonight
through Saturday Morning. Due to saturated soils, this will require
the extension of the flood watch across the northern parts of the
forecast area. Given the expected cloud cover, will trim highs on
Saturday to lower 80s, but higher values will be possible across the
southwest area, farther away from precipitation.

Sunday and Sunday Night...

Northwest flow looks to remains in place on Sunday and yet another
wave looks to pass across Indiana within the flow. A cold front is
expected cross the state on Sunday and Central Indiana will spend
Sunday afternoon within the warm sector ahead of the front. Again
forecast soundings show favorable CAPE in excess of 2400 J/KG and
the very high pwats near 2.2. Thus again, high pops will be needed
in the afternoon and flood potential will still be in play.

Monday and Tuesday...

Dry weather will be expected on Monday and Tuesday as high pressure
remains across the area. Northwest flow will be in place aloft, but
little in the way of forcing dynamics is expected to pass.
Subsidence will be in play as weak ridging will be occurring
upstream over the Rockies. The Canadian high pressure will allow
temperatures to return to near normal or slightly below normal
temperatures with less humidity.

Wednesday...

Best chances for precipitation next week looks to be on Wednesday
into Wednesday Night. A moderate upper short wave within the flow is
expected to pass across the Great Lakes. This along with an
associated cold front is expected to pass across Indiana. With warm
and more humid southerly winds in place across Indiana due to the
departing high pressure system, ample moisture will be available.
Thus pops will be needed. At the moment, best timing looks to be in
the afternoon and evening, but given this many days away this timing
could change.

Thursday and Friday...

Dry weather looks to return for the end of the work week. The
previous cold front will push to the Ohio river by Thursday morning,
allowing high pressure to build across Central Indiana for the end
of the work week. Aloft, stronger ridging is expected over the
Rockies, that should result in more leeside subsidence over the
upper midwest. A caveat is that a weak upper trough will still be
passing across the Great Lakes that could provide some forcing.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 128 AM EDT Sat Aug 15 2026

Impacts:

- Thunderstorms likely at all sites in the 10-19Z time frame
  depending upon the site, earlier in the north and later in
  the south

- Patchy MVFR fog possible near daybreak where convection has
  not yet impacted

Discussion:

Moist low levels may promote some patchy fog development near
daybreak at sites where convection has not yet reached.

Thunderstorms are developing upstream and are expected to progress
into central Indiana late tonight into the midday hours on Saturday.
Will carry TEMPO groups at all sites during the most likely hours
for storms, though it is possible that training occurs and multiple
rounds impact the sites. Periods of MVFR or worse conditions may
occur with the storms, though fluctuations are likely. Ceilings may
be MVFR for a time in the wake of the activity before returning to
VFR.

Winds will be calm to light and variable overnight, becoming more
southerly and then southwesterly with time. Winds are likely to
again go light and variable Saturday evening.

&&

.IND WATCHES/WARNINGS/ADVISORIES...

Flood Watch through this evening for INZ021-028>031-035>049-
051>057-065.

Heat Advisory from 11 AM this morning to 8 PM EDT Sunday for
INZ060>063-067>071.

&&

$$

UPDATE...Updike
AVIATION...Nield
DISCUSSION...Puma