979
FXUS63 KIND 160703
AFDIND

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

.KEY MESSAGES...

- Storm threat continues through tonight, with locally damaging
  winds, heavy rain, and rapid onset flash flooding remaining
  possible

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

- Dry and milder weather early in the work week

- Additional storms possible Wednesday

&&

.DISCUSSION (Today through Saturday)...
Issued at 303 AM EDT Sun Aug 16 2026

THROUGH TONIGHT...

One or more upper level waves, at least partially convectively-
enhanced, will traverse the area this morning into tonight, with
attendant threats for additional showers and thunderstorms. Modest
but sufficient deep layer shear will remain in place, along with
ample instability in the continued warm and very moist environment.
Areas of low level convergence associated both with surface
boundaries and remnant convective outflows will serve as foci for
development, but given the complex situation and CAM struggles with
placement and consistency run-to-run, confidence is lowered.
Localized damaging wind gusts will remain the primary severe threat.

Needless to say, flash flood concerns will remain the most pressing
worry, however. HREF local probability matched means suggest a
threat for up to a 1-2+ inches of rain with the most intense storms,
which will continue to pose a extremely rapid onset flash flood
threat, though there is some guidance suggestion that the heavier
rainfall threat may be more central and south, which, while still
quite wet, is not quite in as rough a shape as areas from Indy metro
north and northeast.

MONDAY AND TUESDAY...

An area of surface high pressure will mercifully bring at least a
temporary end to the repeated rounds of thunderstorms early in the
week, with dry weather and near normal temperatures likely early
Monday into Tuesday.

TUESDAY NIGHT INTO WEDNESDAY NIGHT...

Unfortunately, an additional round of thunderstorms appears likely
late Tuesday night into Wednesday night as another cold front and
upper level wave accompanying a strong jet streak aloft passes
through the region. Plentiful moisture will be available, though
precipitable water values may be slightly more modest (70-80th
percentile climatologically). However, somewhat stronger deep layer
shear may be available. Another round of severe storms will
certainly be possible, though predictability is greatly limited
given the sensitivity to prior rounds of storms and model
inconsistencies 4 days out.

That said, even with a couple of days to dry out, flash flood
vulnerability will remain quite high in the face of any additional
convective rainfall given the extreme antecedent conditions, and we
will need to remain vigilant through at least mid week for these
concerns.

THURSDAY ONWARD...

Amplification of the upper ridge over the western CONUS and
southward displacement of both the frontal zone and deeper moisture
by surface high pressure and upper level troughing suggest milder
temperatures and mostly dry conditions late week and into the
weekend, though some slight chances for showers or storms may linger
across the southern portions of central Indiana. It will take quite
some time for antecedent conditions to significantly improve,
unfortunately, and any additional convective rainfall with periodic
frontal passages or upper level waves in the broader cyclonic flow
next weekend and into the following week will pose at least modest
flash flood threats.

&&

.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.

&&

$$

AVIATION...Nield
DISCUSSION...Nield