068
FXUS63 KIND 162316 AAA
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
Issued by National Weather Service Northern Indiana
715 PM EDT Sun Aug 16 2026

.KEY MESSAGES...

- Storm threat continues through tonight, with locally damaging
  winds and heavy rain possible, mainly across southern Central
  Indiana.

- 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 mid week.

&&

.MESOSCALE UPDATE...
Issued at 340 PM EDT Sun Aug 16 2026

A small MCS over central Illinois is in a not in a particularly
sheared environment, thus a less consolidated look with individual
short-lived convective cells immediately behind the progressing
outflow. VWP-derived winds show enhancement at around 3-km to about
40-knots, explaining its forward speed. The downstream environment
is moderately unstable and midlevel flow stays somewhat enhanced, so
this loosely organized cluster will probably persist into west-
central Indiana after 4:30-5:00 with strong wind gust potential.
Sporadic marginally severe wind gusts are possible.

Otherwise, individual cells developing within moderately unstable
atmosphere across portions of central Indiana may post brief strong
wind gusts, but will struggle to organize given weak deep layer
shear. Anomalous moisture and deep warm cloud layer will support
brief heavy downpours, and this would exacerbate flooding across
saturated ground. 1-hr flash flood guidance is depressed to as low
as 0.75" in some areas, particularly over portions of Delaware and
Randolph counties.

&&

.DISCUSSION (This evening through Sunday)...
Issued at 146 PM EDT Sun Aug 16 2026

Surface analysis this afternoon shows low pressure in place over
Ontario, with a weak trough of low pressure stretching south to
eastern Indiana. Aloft, water vapor imagery continues to show a
plume of tropical moisture stretching from the American southwest
across the central Plains to the Great Lakes and Indiana. A
convective cluster was found over western IL, moving east within the
flow and has started to strengthen once again as daytime heating has
lead to warm and unstable air flowing into the system. GOES19 shows
cooling cloud tops here. Radar shows an area of scattered light
showers associated with the trough, over SW Central Indiana, pushing
east. Dew points across Central Indiana remained quite miserable, in
the middle 70s.

This afternoon and Tonight...

Diurnal heating is leading to convection, mainly across the southern
half of Central Indiana where the boundary is. SPC meso analysis
suggests limited CIN across the area will be gone soon, leading to
CAPE in excess of 3000 J/KG in place, able to fire storms. Thus best
pops for the afternoon will remain mainly south of I-70. As heating
is lost this evening, showers and storms will diminish.

Overnight, the HRRR suggests another nocturnal batch of
thunderstorms to push across southern Central Indiana, due to
embedded waves within in the flow aloft. Storms look to reach the
Wabash by midnight, and exit the area by 6 AM. Fortunately, tracking
of this system appears to follow the boundary across southern Central
Indiana, keeping the rain soaked northern counties mainly dry. Thus
will focus best overnight pops closest to the boundary, across
southern Indiana, and mainly late tonight. Some low pops may still
be needed across the northern forecast area, but any amounts should
be minimal. High dew points will continue to remain across Central
Indiana tonight. Lows should be near persistence.

Monday and Tuesday...

Dry, slightly cooler and slightly less humid weather is expected to
arrive to start the work week. Through Tuesday, the upper flow
becomes northwesterly and little in the way of forcing dynamics
appear to pass. Subsidence and mid level drying begin settle across
Indiana as the upper tropical plume flow shifts farther south.
Meanwhile at the surface, high pressure over the plains builds east
to Indiana through Tuesday. Forecast soundings show a dry column
across Indiana for much of Monday and Tuesday. Thus clouds will exit
on early monday morning with the departure of the overnight system,
leading to mainly partly cloudy skies for the rest of Monday and
Tuesday. Cooler NW winds will allow for dew points to fall into the
60s and highs will be cooler, only in the lower to middle 80s.

Wednesday and Thursday...

Dry weather will expected to start the day on Wednesday as high
pressure will exiting the Ohio Valley to the east. Low pressure over
the plains is expected to push a warm front into Indiana by late
afternoon on Wednesday and Wednesday Night. Northwest flow looks to
be in place aloft, and embedded short waves will be possible. On
Thursday, models suggest this stationary front over Indiana, and for
now, this will require pops starting on Wednesday afternoon,
continuing through Thursday night.

Friday...

Surface high pressure is suggested to remain over Indiana on Friday,
providing a cooler and drier NE flow. Models still do keep NW flow
in place aloft with a trough approaching from the NW. However deep
moisture will be more limited as NE winds allow for dew points to
fall in to the 50s. Thus for now will try and use a dry forecast,
but this could easily change given the flow aloft and the possibility
of stronger forcing. Thus confidence is low.

Saturday And Sunday...

On Saturday, the models suggest building ridging aloft over the high
plains, resulting in a more amplified pattern and troughing digging
through the eastern Great Lakes and Appalachia. Upper support within
the flow is shown to pass on Saturday, while the tail of a cold
front moving across the Great Lakes will sweep across Indiana. Thus
pops will be needed on Saturday. On Sunday the building ridge west
of Indiana will create strong subsidence over the upper midwest,
spilling southeast toward Indiana. This will create a surface high
pressure system building across Indiana along with most likely dry
weather.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 715 PM EDT Sun Aug 16 2026

Area of thunderstorms has cleared all sites with VFR cigs and
somewhat variable post storm wind direction expected. CAMs still
leaning towards another area of storms moving west to east across
the area overnight. This may be taking shape from KGBG to KUIN as
well as some activity well ahead of this. Given this same area will
need some recovery after the first round, overall confidence on
impacts are on the lower side. Timing in previous TAFs looks good,
so will continue with a Prob30 for the southern 3 sites and
introduce a Prob30 at KLAF who possibly has a shot as well, but not
enough confidence for a predominate group. Some post frontal stratus
could settle in into mid morning.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT this evening for INZ060>063-067>071.

&&

$$

MESOSCALE...BRB
AVIATION...Fisher (WFO IWX)
DISCUSSION...Puma