Severe Thunderstorm Warning 261, NWS Northern Indiana

Area Forecast Discussion
National Weather Service Northern Indiana
625 AM EDT Tue Aug 11 2026

.KEY MESSAGES...

- Showers and thunderstorms will continue through mid-morning in
some areas, with heavy rain the main concern. A line of strong to
severe storms, accompanied by damaging winds, looks to arrive this
afternoon.

- The potential for flooding may increase today from both recent
rainfall and additional heavy rainfall through tonight. A Flood
Watch is in effect for most of the area.

- Rain chances may linger through the week, especially south of US-
30.

&&

.DISCUSSION...
Issued at 129 AM EDT Tue Aug 11 2026

Quasi-stationary boundary remains in nearly the same area as 24
hours ago, from near Davenport, IA east to Chicago and then curving
towards Detroit. Much like last night, an area of showers and storms
has exited the forecast area with attention turning upstream across
E IA into N IL where CAMs develop additional convection over the
next several hours and track E or SE. As of 5Z a few cells have
popped from near Gary NW to Poplar Grove IL. Intensification has
been on the slower side, but LLJ is starting to increase with 25 to
30 kts now noted on VADs in Iowa and central IL and mesoanalysis
shows a pocket of over 2000 J/KG of MLCAPE. Pops have been adjusted
somewhat, but may need further changes later depending on evolution.
A threat for large hail, locally gusty winds, frequent lightning and
heavy rain would be the main concerns.

Towards 12Z most of the activity looks to push away with several
CAMs hinting at new development along the washed out boundary from W
of Chicago to White county. As the low level flow increases from the
SW, this looks to shift NE allowing a small window for rapid
destabilization. With MLCAPE over 2000 J/KG, DCAPE over 1000 J/KG
and at least modest shear. A line of showers and storms is expected
to develop upstream and dive quickly SE, arriving as early as 18Z in
W/NW areas. Some concerns that the morning convection could impact
the overall strength of the line and possibly focus the greater wind
threat SW of us. Upper level flow, approaching wave and other
factors above all point towards the potential of a higher end wind
event along with a small chance of brief spin ups. New SWODY1
maintains the Enhanced risk across the SW half of the area with a
CIG1 hatching for the increased wind threat. Alignment of best pops
may change this morning as we see what, if any impacts occur from
overnight and early morning convection.

In addition to the severe threat, flooding concerns will remain on
the front burner as swaths of heavier rainfall have occurred across
the CWA over the past couple of days, most recently in SE area.
Given the lower confidence on the evolution of convection through
early evening was going to hold on any flood watch, but after
collaboration in house and surrounding offices decided to hoist a
Flood Watch for all of our IN and OH counties with most of our MI
counties spared of the worst rainfall.

The line should quickly push out near/after 00Z Wed with the frontal
boundary finally getting a nudge south into central IN. Does this
mean that Wed and beyond will see much calmer conditions...probably
not as the entire upper level flow really doesn't change much the
remainder of the week and troughs moving through the area will cause
the front to shift north and south. As a result, pops remain riddled
in several period through the remainder of the forecast. Given the
challenges the next 12 to 24 hours, anything outside tonight was
left alone.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 625 AM EDT Tue Aug 11 2026

Generally VFR conditions expected outside of periods of convection
through today. There may be some brief MVFR cigs through 15Z, but
expect cloud bases to generally be above 025 afterwards. For the
next few hours, convection will be primarily focused towards FWA
with lower chances at SBN, but as additional thunderstorms develop
towards the afternoon, periods of MVFR to IFR vsbys are likely along
with outflow driven gusts of 30-40kts. Outside of convection, there
may be a few southwesterly wind gusts up to 20kts but these gusts
should remain infrequent. Chances for convection look to lower after
00Z with the development of fog/low stratus likely after 06Z through
the end of the TAF period.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Flood Watch from 11 AM EDT /10 AM CDT/ this morning through
     this evening for INZ005>009-012>015-017-018-020-022>027-
     032>034-103-104-116-203-204-216.
OH...Flood Watch from 11 AM EDT this morning through this evening
     for OHZ001-002-004-005-015-016-024-025.
MI...None.
MARINE...None.

&&

DISCUSSION...Fisher
AVIATION...NWS

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Special Weather Statement
National Weather Service Northern Indiana
527 AM EDT Tue Aug 11 2026

INZ015-022>024-216-111000-
Miami IN-Wabash IN-Southern Kosciusko IN-Cass IN-Fulton IN-
527 AM EDT Tue Aug 11 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN WABASH...
SOUTHWESTERN KOSCIUSKO...FULTON...NORTHEASTERN CASS AND NORTHWESTERN
MIAMI COUNTIES THROUGH 600 AM EDT...

At 527 AM EDT, Doppler radar was tracking a strong thunderstorm 7
miles southwest of Rochester, moving east at 35 mph.

HAZARD...Wind gusts up to 50 mph and penny 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...
Rochester, Akron, Silver Lake, Kewanna, Denver, Roann, Fulton, Macy,
Chili, Stockdale, Nyena Lake, Deedsville, Athens, Beaver Dam Lake,
Bruce Lake Station, Grass Creek, Beaver Dam, Fletcher, Lake Manitou,
and Gilead.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4091 8648 4091 8647 4094 8647 4111 8643
      4109 8584 4083 8586
TIME...MOT...LOC 0927Z 275DEG 32KT 4100 8632

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

FISHER

Special Weather Statement
National Weather Service Northern Indiana
613 AM EDT Tue Aug 11 2026

INZ008-014-017-116-216-111045-
Whitley IN-Noble IN-Southern Kosciusko IN-Marshall IN-
Northern Kosciusko IN-
613 AM EDT Tue Aug 11 2026

...STRONG THUNDERSTORMS WILL IMPACT SOUTHWESTERN NOBLE...NORTHERN
WHITLEY...KOSCIUSKO AND SOUTHERN MARSHALL COUNTIES THROUGH 645 AM
EDT...

At 613 AM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Argos to near Bourbon to 7 miles southwest
of Winona Lake. Movement was east at 30 mph.

HAZARD...Wind gusts of 50 to 55 mph and half inch 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...
Warsaw, Columbia City, Winona Lake, Tri-lakes, Bourbon, Argos, North
Webster, Pierceton, Mentone, Tippecanoe, Etna, Silver Lake, Etna
Green, Leesburg, Claypool, Larwill, Burket, Sidney, Big Barbee Lake,
and Ridinger Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4139 8594 4135 8561 4117 8536 4107 8591
      4123 8616 4125 8640
TIME...MOT...LOC 1013Z 253DEG 28KT 4127 8622 4125 8608 4114 8591

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...55 MPH

FISHER

Preliminary Local Storm Report
National Weather Service Northern Indiana
708 AM EDT Tue Aug 11 2026

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

0708 AM     Hail             2 ENE Chain-O-Lakes     41.71N 86.34W
08/11/2026  M0.88 Inch       St. Joseph         IN   Trained Spotter

&&