Severe Thunderstorm Warning 309, NWS Indianapolis, IN

Area Forecast Discussion
National Weather Service Indianapolis IN
249 PM EDT Wed Aug 12 2026

.KEY MESSAGES...

- Marginally severe storms through daybreak along with potential
  additional flooding

- Flood Watch continues through today with additional strong to
  severe storms through the day, mainly during the afternoon

- Damaging winds will be the main threat today outside of flooding

- Storm chances continue through the rest of the week, severe
  weather threat looks lower

&&

.DISCUSSION (This evening through Wednesday)...
Issued at 249 PM EDT Wed Aug 12 2026

Surface Analysis this afternoon shows a broad surface trough
stretching from central IL to across Central Indiana. Convection
continued along this trough spreading showers and thunderstorms
across much of Central Indiana. Water vapor shows a steady NW flow
aloft in place, with an wave over IL, generating convection
downstream. Dewpoints remained high, in the 60s as much of the area
was under the influence of rain cooled air, however across southwest
Central Indiana, dew points were in the 70s, providing very humid
conditions along with the best instability.

This afternoon through the overnight...

The Thunderstorm complex over Central Indiana will continue to
propagate SE across Central Indiana through the late afternoon
hours. Heavy rains may result in additional flooding and severe
storms cannot be ruled out. Near 00Z the HRRR progresses this system
further SE, exiting Central Indiana as the forcing with upper wave
exits. Clouds will remain across the area through the evening with
rain cooled air in place.

Overnight as the LLJ resumes, more storm development will be
possible, but at this time HRRR is developing storms along the
boundary which at that time should be located across southern
Central Indiana due to the southward push from today's convection.
Thus will focus best pops overnight in those locations. Fog will
also be possible overnight due to high dew points, light winds and
plenty of lingering lower level moisture.

Thursday and Thursday Night...

More rain chances will be expected on Thursday afternoon and into
Thursday night. The persistent NW flow aloft is once again expected
to continue across central Indiana. An upper level wave is expected
to pass across central Indiana providing forcing through the
afternoon hours. The location of the surface trough will be key in
best initiation and propagation area. For now, this is suggested to
be across southern Central Indiana, but changes can occur overnight.
Forecast soundings show shallower CAPE at that time with values only
around 1000-1500 J/kg across Central Indiana, but much higher values
south of boundary in the warmer and humid air mass. Thus will again
use high pops on Thursday afternoon for more showers and storm
development given the familiar, favorable set-up in place. Again,
best chances for now will be across southern Central Indiana which
is the expected location of the surface trough. Flash Flood Watch
will be extended.

Friday and Friday Night...

Strong ridging within the upper flow is expected to push east toward
Indiana on Friday. This will allow surface warm front to surge
across Central Indiana as flow becomes southwesterly. Forecast
soundings again on Friday show a nearly saturated column at times,
with pwats once again over 2 inches. Again shallow CAPE appears
available. Thus again likely pops will be needed from the afternoon
and into the evening as the warm front surges northeast across the
area and acts as a focus for convection.

Saturday through Sunday Night...

Rain chances will persist on Saturday and Sunday as a warm frontal
boundary is suggested to be lingering across Central Indiana.
Working against this will be the pattern aloft where upper level
ridging will be building across Indiana from the west. This will
result in some subsidence within the mid and upper levels. However,
diurnal convection cannot be ruled out due to the frontal boundary
that will be present across the area on Saturday as a warm front and
on Sunday as a cold front crossing Indiana. SW flow ahead of the
cold front will result in hot weather on Saturday and again on
Sunday with highs in the 90s.

Monday through Wednesday...

Better chances for dry weather and temperatures closer to normal
will be expected during this time. Northwest flow is expected to
resume across the area on Monday due to upper ridging in place over
the Rockies. Little in the way of forcing looks to pass during this
time. Meanwhile at the lower levels, stronger Canadian high pressure
will be building behind Sunday's cold front on Monday and through
the first part of the next work week. This should result in partly
cloudy skies and highs in the 80s. Temps will moderate by Wednesday
as the surface high drifts farther east and southerly return flow
begins.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 249 PM EDT Wed Aug 12 2026

Impacts:

- Thunderstorms moving across the area through 22Z. Brief MVFR
conditions possible with any TSRA that strikes a TAF site.

- Fog development expected tonight, especially near LAF/HUF.
Possible MVFR/IFR.

- TSRA return on Thursday after 18Z.

Discussion:

Thunderstorm complex across across Indiana will be passing across
HUF and IND near 18Z, then diving south to BMG by 19Z-20Z. MVFR
conditions will be possible with any TSRA.

HRRR suggests the convection dives SE and ends this evening. This
should lead to some convective debris clouds providing VFR Cigs
through the evening and overnight. Fog will be possible overnight,
as light winds, high dew points and recent rain provide good
conditions for fog development.

Additional convection will be possible after 18Z on Thursday as
another upper wave arrives and interacts with the warm and humid air
mass across central Indiana.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Thursday evening for INZ021-028>031-035>049-
054>057-063>065-072.

Flood Watch through Thursday evening for INZ051>053-060>062-
069>071.

&&

AVIATION...Puma
DISCUSSION...Puma

Hazardous Weather Outlook
National Weather Service Indianapolis IN
1111 AM EDT Wed Aug 12 2026

INZ021-028>031-035>049-051>057-060>065-067>072-131515-
Carroll-Warren-Tippecanoe-Clinton-Howard-Fountain-Montgomery-Boone-
Tipton-Hamilton-Madison-Delaware-Randolph-Vermillion-Parke-Putnam-
Hendricks-Marion-Hancock-Henry-Vigo-Clay-Owen-Morgan-Johnson-Shelby-
Rush-Sullivan-Greene-Monroe-Brown-Bartholomew-Decatur-Knox-Daviess-
Martin-Lawrence-Jackson-Jennings-
1111 AM EDT Wed Aug 12 2026

This hazardous weather outlook is for central Indiana.

.DAY ONE...Through Tonight.

Flooding and flash flooding will continue across eastern Indiana.
More showers and storms are expected. This may result in additional
flooding or a worsening of ongoing flooding.

Damaging winds will also be possible with thunderstorms this
afternoon and into the evening.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Thunderstorms will be possible at times through the week, with
potential for multiple rounds of severe storms through at least
Thursday. Damaging winds and heavy rainfall will be the primary
threats.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to remain vigilant this week as multiple rounds
of severe storms will be possible.

&&

More information, along with other weather, hydrological and climate
information can be found at http://weather.gov/ind

JP

Preliminary Local Storm Report
National Weather Service Indianapolis IN
253 PM EDT Wed Aug 12 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1153 AM     Flash Flood      1 NW New Castle         39.93N 85.38W
08/12/2026                   Henry              IN   Public

            Flooding at Kroger, a gas station, and road
            intersections.

&&

BH

Special Weather Statement
National Weather Service Indianapolis IN
254 PM EDT Wed Aug 12 2026

INZ063>065-072-121930-
Brown IN-Decatur IN-Bartholomew IN-Jennings IN-
254 PM EDT Wed Aug 12 2026

...Strong thunderstorms will impact portions of southern Decatur,
Brown, Bartholomew and northern Jennings Counties through 330 PM
EDT...

At 254 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from Greensburg to Columbus to Nashville. Movement
was southeast at 30 mph.

HAZARD...Wind gusts up to 50 mph and very heavy rain.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs or uproot some
         trees, and blow around unsecured objects.

Locations impacted include...
Columbus, Greensburg, Nashville, Edinburgh, Hope, Westport,
Elizabethtown, Hartsville, Clifford, Jonesville, Millhousen, Peoga,
Newbern, Beanblossom, Gnaw Bone, Nebraska, Spurgeons Corner, Azalia,
Elkinsville, and Country Squire Lakes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

A Severe Thunderstorm Watch remains in effect until 500 PM EDT for
central, south central and southeastern Indiana.

&&

LAT...LON 3920 8544 3904 8544 3905 8580 3907 8580
      3904 8587 3905 8637 3934 8638 3935 8557
      3928 8530
TIME...MOT...LOC 1854Z 294DEG 25KT 3933 8545 3920 8589 3919 8621

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

BRB

Preliminary Local Storm Report
National Weather Service Indianapolis IN
307 PM EDT Wed Aug 12 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0230 PM     Flash Flood      1 SE Brownsburg         39.83N 86.39W
08/12/2026                   Hendricks          IN   Public

            Flooding near Brownsburg High School with an
            estimated depth around 5-6 inches.

&&

BH

Preliminary Local Storm Report
National Weather Service Indianapolis IN
312 PM EDT Wed Aug 12 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0250 PM     Flash Flood      1 ENE New Castle        39.92N 85.35W
08/12/2026                   Henry              IN   Emergency Mngr

            Evacuation of an apartment building on the
            east side of New Castle due to flooding.

&&

BH

Preliminary Local Storm Report
National Weather Service Indianapolis IN
319 PM EDT Wed Aug 12 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0305 PM     Tstm Wnd Dmg     3 NNW Bruceville        38.79N 87.44W
08/12/2026                   Knox               IN   Emergency Mngr

            Possible tornado. Debris in the air and
            trees blown down.

&&

BH

Preliminary Local Storm Report
National Weather Service Indianapolis IN
322 PM EDT Wed Aug 12 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0200 PM     Flash Flood      1 NW New Castle         39.93N 85.38W
08/12/2026                   Henry              IN   Dept of Highways

            Road closed due to flooding on IN 3 between
            Indiana Ave and IN 38 (New Castle).

&&

BH