Severe Thunderstorm Warning 302, NWS Indianapolis, IN

Area Forecast Discussion
National Weather Service Indianapolis IN
1026 PM EDT Tue Aug 11 2026

.KEY MESSAGES...

- Thunderstorms will be around at times through the night and
  into Wednesday

- Flood Watch through Wednesday across much of central Indiana

- Additional storms daily through the rest of the week, flooding
  will be the main threat

&&

.FORECAST UPDATE...
Issued at 1026 PM EDT Tue Aug 11 2026

Although the large outflow boundary from earlier severe convection
has pushed south and west of central Indiana, isolated thunderstorms
continue to develop along a different boundary from near Lafayette
to Martinsville to east of Seymour. These are tapping into some
elevated instability and will become briefly strong at times.

During the night, upper impulses will work with warm advection to
generate additional convection across the area. MLCAPE will increase
thanks to the advection, so strong to potentially severe storms
remain a threat (as shear remains decent). However, uncertainty
remains on how much coverage there will be and on where the most
coverage will occur. For now believe the most coverage will be
across the northeast half of the area, so went high chance to low
end likely PoPs there. Went lower PoPs elsewhere.

With the rain that fell so far today, and the high moisture content
of the atmosphere, flooding remains a concern through the night.
This is especially true across the northeast where the heaviest rain
fell.

Rain cooled air will keep temperatures nearly steady through the
night. If clouds thin/clear out for long enough, fog may develop.

&&

.DISCUSSION (This evening through Tuesday)...
Issued at 233 PM EDT Tue Aug 11 2026

Surface analysis this afternoon continues to show a weak trough of
low pressure stretching from northern IL across northern Indiana
into OH. This area remains the focus for convective development.
GOES19 shows a large thunderstorm cluster over northern Indiana,
progressing to the southeast. Thunderstorms were found stretching
from a LAF to Noblesville-Anderson-Muncie areas, and was sagging
southward. Best instability across area remained southwest of the
storms where SPC CAPE showed values over 4500 J/KG. Latest ACARS
soundings show deep CAPE available. Aloft water vapor shows a short
wave within the NW flow aloft over eastern IL triggering our
convective cluster as the NW flow continue to stream from MT and WY
to Indiana.

This afternoon and tonight...

Convection across the northern parts of the forecast area is
expected to continue for the next several hours as the upper wave
continues to progress east. Thunderstorms will try to sag southward
somewhat, where the better instability will be located. Thus will
continue to keep high pops in place in this along and south of the
storms through the afternoon into the evening. Additional TSRA due
to daytime heating will be possible across southwestern central
Indiana and lower pops will still be needed there.

HRRR shows this wave exiting by early evening, and a worked over
atmosphere should allow storms to end leading to a mainly dry
evening and overnight period. Some fog will be possible near LAF due
to the high dew points remaining across the area along with the
lingering surface boundary.  Look for overnight lows in the lower
70s and the highest pops during the evening hours.

Wednesday...

The persistent NW flow aloft is expected to remain in place on
Wednesday, perhaps becoming a bit more northwesterly as yet another
short wave is expected to pass across Central Indiana within the
flow. Again the very warm and humid air mass will be in place
allowing for plenty of moisture and pwats once again are near values
1.81 inches. Again ample CAPE will be in play also. Thus high pops
will once again be used on Wednesday as this wave will pass, mainly
in the afternoon. With a good amount of daytime heating available
through the morning hours, high temperatures should again reach the
upper 80s to around 90.

Wednesday Night through Thursday Night...

Through this time period there is very little change in the overall
weather pattern. The same NW flow aloft is expected to be in place
with several embedded waves within that flow poised to pass during
this time period. The very warm, humid and unstable airmass will
also remain. All of this will add up to continued chances for
showers and thunderstorms, mainly capable of producing very heavy
rain and damaging wings through the period. Continued pops will be
used through the period.

Friday through Sunday Night....

More hot and humid weather is expected through the weekend along
with daily chances for showers and thunderstorms. Models suggest
ridging aloft over the plains will be building across Central
Indiana through the weekend. A few ridge riding waves within a ring
of fire type pattern will be capable of producing occasional showers
and storms. Further support will come from the lower levels. Here, a
frontal boundary will be lingering across Central Indiana on Friday
before pushing north as a warm front on Saturday ahead of low
pressure over the plains. The low will push east of Indiana on
Sunday, likely dragging a cold front across Central Indiana.
Forecast soundings through Sunday show plentiful moisture available
through the column. All of this will again necessitate pops through
the weekend. The warm air mass will result in high temperatures in
the upper 80s to around 90.

Monday and Tuesday...

In the wake of the front on Monday, dry air and subsidence is shown
to arrive as high pressure from the Great Lakes builds across
Central Indiana. Forecast soundings show a dry column and for the
first time in what seems like a long time show zero CAPE. Aloft,
ridging is expected to return over the Rockies resulting in NW flow
streaming across the plains into Indiana. At the moment it appears
that little to no forcing will be available, this we should able to
use a dry forecast at that time given the the expected surface high
pressure.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 728 PM EDT Tue Aug 11 2026

Impacts:

- Uncertainty on storm timing through tomorrow; periodic storms
expected
- Low confidence threat of fog for LAF and HUF late tonight

Discussion:

Organized thunderstorm complex is south of TAF sites as of this
writing, with stratiform trailing rain for a few more hours.
Concerns are for redevelopment of thunderstorms in Illinois within
warm advection regime atop residual outflow tonight, and this is
particularly difficult to time. We have attempted to highlight most
likely window for thunderstorms but this will likely need to be
refined through amendments as trends continue to be monitored.

Depending on thunderstorms and residual clouds, there remains a
conditional setup for fog at/near LAF and HUF, though confidence is
lower than previous forecasts.

Depending on the expansiveness of storms later tonight and tomorrow
morning, afternoon redevelopment is likely. Again, timing and
coverage is in question so we have a broader prob30 for now. Expect
adjustments to timing and we cannot completely rule out storms at
any TAF sites at any time during the 30 hour forecast period.

&&

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

&&

UPDATE...50
AVIATION...BRB
DISCUSSION...Puma

Hazardous Weather Outlook
National Weather Service Indianapolis IN
1054 PM EDT Tue Aug 11 2026

INZ021-028>031-035>049-051>057-060>065-067>072-130300-
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-
1054 PM EDT Tue Aug 11 2026

This hazardous weather outlook is for central Indiana.

.DAY ONE...Tonight.

Thunderstorms will continue to develop across central Indiana at
times tonight. Some storms may become severe, with damaging winds and
large hail the main severe threats. Heavy rain is possible with any
thunderstorm, which could lead to flooding.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

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, but large hail and isolated tornadoes are also possible
through Wednesday.

.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

Preliminary Local Storm Report
National Weather Service Indianapolis IN
1113 PM EDT Tue Aug 11 2026

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

1110 PM     Hail             4 E Southport           39.65N 86.04W
08/11/2026  E1.00 Inch       Marion             IN   Public

            Report from mPING: Quarter (1.00 in.).

&&

AW

Preliminary Local Storm Report
National Weather Service Indianapolis IN
1116 PM EDT Tue Aug 11 2026

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

0629 PM     Tstm Wnd Dmg     Martinsville            39.43N 86.43W
08/11/2026                   Morgan             IN   Public

            Several tree branches downed.

&&

AW

Preliminary Local Storm Report
National Weather Service Indianapolis IN
1127 PM EDT Tue Aug 11 2026

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

0711 PM     Hail             3 SE Cannelburg         38.64N 86.96W
08/11/2026  E1.00 Inch       Daviess            IN   Public

            Time estimated from radar.

0714 PM     Tstm Wnd Dmg     4 NE Country Squire Lak 39.09N 85.64W
08/11/2026                   Jennings           IN   Public

            Power lines over SR 3. Time estimated from
            radar.

0934 PM     Tstm Wnd Dmg     Belle Union             39.57N 86.71W
08/11/2026                   Putnam             IN   Public

            Several large tree limbs downed. Time
            estimated from radar.

&&

Preliminary Local Storm Report
National Weather Service Indianapolis IN
1133 PM EDT Tue Aug 11 2026

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

1115 PM     Hail             6 NNW Boggstown         39.65N 85.97W
08/11/2026  M1.25 Inch       Marion             IN   Fire Dept/Rescue

&&

AW

Preliminary Local Storm Report
National Weather Service Indianapolis IN
1138 PM EDT Tue Aug 11 2026

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

0721 PM     Hail             2 WSW Prairie Creek     39.30N 87.56W
08/11/2026  E1.75 Inch       Vigo               IN   Broadcast Media

&&

AW

Special Weather Statement
National Weather Service Indianapolis IN
1144 PM EDT Tue Aug 11 2026

INZ048-056-057-065-120415-
Rush IN-Decatur IN-Shelby IN-Hancock IN-
1144 PM EDT Tue Aug 11 2026

...A strong thunderstorm will impact portions of northeastern Shelby,
south central Hancock, western Rush and northwestern Decatur Counties
through 1215 AM EDT...

At 1144 PM EDT, Doppler radar was tracking a strong thunderstorm near
Shelbyville, moving east at 30 mph.

HAZARD...Winds in excess of 30 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Shelbyville, Adams, Morristown, St. Paul, Fairland, Manilla, Waldron,
Moscow, and Arlington.

This includes Interstate 74 between mile markers 107 and 131.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3953 8586 3969 8585 3974 8545 3933 8553
TIME...MOT...LOC 0344Z 275DEG 27KT 3961 8574

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...30 MPH

KF