Alert archive / Iowa / Severe Thunderstorm Warnings in 2026

Severe Thunderstorm Warning 97, NWS Des Moines, IA

April 17, 2026Poweshiek County, Tama County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Apr 17, 2026, 4:02 PM CDT for Poweshiek County, Tama County, Iowa. It was in force for 15 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Apr 17, 2026, 4:02 PM CDT (21:02 UTC)
Expired: Apr 17, 2026, 4:17 PM CDT
In force: 15 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.25 in
Wind: 50.0 mph

Counties Poweshiek County, IA, Tama County, IA

The radar

The Des Moines radar (KDMX), 100 km from the middle of the area, began a volume at 21:02 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Apr 17, 12:40 PM CDT	Tornado Watch	SPC	9 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 9.0 hours before the alert went out and 341 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2301 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 188 m²/s²
0-3 km storm-relative helicity: 229 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Des Moines, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 17, 1:01 PM CDT, 3 hours 1 minute earlier. Its key messages:

Enhanced Risk (level 3 of 5) in eastern Iowa. All severe hazards, including large hail, damaging wind, and tornadoes, are possible with storms today.
Much cooler this weekend with overnight lows in the 20s and 30s.
Mild and dry to start the week with thunderstorms returning to the forecast by late week.

Area forecast discussion, Apr 17, 1:01 PM CDT, 3 hours 1 minute before

Area Forecast Discussion
National Weather Service Des Moines IA
101 PM CDT Fri Apr 17 2026

.KEY MESSAGES...

- Enhanced Risk (level 3 of 5) in eastern Iowa. All severe
  hazards, including large hail, damaging wind, and tornadoes,
  are possible with storms today.

- Much cooler this weekend with overnight lows in the 20s and 30s.

- Mild and dry to start the week with thunderstorms returning to
  the forecast by late week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 101 PM CDT Fri Apr 17 2026

The surface low early this afternoon is centered across north
central Iowa with attendant sharp cold front pushing across the
state. The impact was already being felt this morning in
northwest Iowa when Estherville fell from 71 degrees at 10am to
43 degrees by 10:07am. Early convection has bubbled in northern
Iowa and into Minnesota associated with lift in the vicinity of
the surface low. The cold air sharply undercuts the warm and
deeply unstable air in place with the primary trough farther to
the west. This will allow for a period of some post-frontal
elevated storm development, something already noted with
elevated showers in northwest Iowa this morning behind the
surface front. Across the state two primary ares of convective
development are anticipated into the afternoon, noted in midday
satellite imagery. The first is pre-frontal convection
developing in an area of convergence noted in surface
observations across eastern Iowa and visible in a plume of
cumulus. A second line of cumulus trails along the cold front
across western Iowa that will push across Iowa through the rest
of the afternoon.

Much of the prefrontal convection is expected to develop east of the
area, perhaps clipping far southeastern parts of the area near
Ottumwa. There is plenty of available instability with 3000-4000
J/kg of MUCAPE (3000+ MLCAPE) and steep mid level lapse rates of 8+
C/km. Much of this instability is elevated with very little in
the lowest 3 km (<100 J/kg). This will limit low level
stretching and some of the tornado potential locally, though it
is certainly NOT eliminated. The steep mid-level lapse rates,
along with well curved hodographs in the low levels will help
with rotating updrafts and hail growth. Storms are expected to
quickly grow upscale. As this happens the initial discrete
development will become multi-cell to linear as it pushes east,
transitioning to a damaging with threat with tornado potential
along the line.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 101 PM CDT Fri Apr 17 2026

Much colder air pushes in with the cold front as temperatures fall
into the 30s tonight. Saturday remains breezy with continued cold
air advection and the enhanced pressure gradient across the area.
Temperatures in the upper 40s north to mid 50s south with 20-25
mph wind through the day. By Sunday winds relax with
temperatures warming slightly into the 50s to low 60s. The
thermal ridge builds next week, bringing 70s back to the area.
Much of the week is dry with storm chances returning late in
the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1236 PM CDT Fri Apr 17 2026

Breezy southerly winds are increasing across the area ahead of a
strong cold front moving across the state today with gusts of
25-30 kts. The front will sweep through this afternoon, exiting
east after 00z. Early storms have bubbled across northern Iowa
this morning and may come near KMCW in the next hour or so,
however recent trends indicate this should miss KMCW so have
kept from that TAF at this time. The main line of storms will
develop in east central Iowa. This may come near KDSM and KALO,
however satellite shows initiation should be just east of those
sites so have removed mentions from those sites. KOTM will see
the bulk of thunderstorm activity this afternoon from around
19-20z through 00s.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
None.

&&

SHORT TERM...Hagenhoff
LONG TERM...Hagenhoff
AVIATION...Hagenhoff

Hazardous weather outlook, Apr 17, 4:38 AM CDT, 11 hours 24 minutes before

Hazardous Weather Outlook
National Weather Service Des Moines IA
438 AM CDT Fri Apr 17 2026

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-180945-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Sac-Calhoun-
Webster-Hamilton-Hardin-Grundy-Black Hawk-Crawford-Carroll-Greene-
Boone-Story-Marshall-Tama-Audubon-Guthrie-Dallas-Polk-Jasper-
Poweshiek-Cass-Adair-Madison-Warren-Marion-Mahaska-Adams-Union-
Clarke-Lucas-Monroe-Wapello-Taylor-Ringgold-Decatur-Wayne-
Appanoose-Davis-
438 AM CDT Fri Apr 17 2026

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Today and tonight

There is an Enhanced Risk (Level 3 of 5) for severe thunderstorms
across southeast Iowa on Friday. There is a Slight Risk (Level 2
of 5) for severe storms more into central Iowa. Damaging winds
and tornadoes are the primary threats. Large hail is also
possible, especially early in the event.

Additional rises on rivers and streams, with localized minor
flooding possible. Ponding and low-end flash flooding is also
possible, especially in urban areas.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Freezing temperatures are expected in northern Iowa Friday night
and across much of the area Saturday night.

Thunderstorm chances return Thursday.

.SPOTTER INFORMATION STATEMENT...

Spotters will be needed this afternoon.

In the hours before

Local storm report, Apr 17, 3:19 PM CDT, 43 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
319 PM CDT Fri Apr 17 2026

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

0318 PM     Hail             Melrose                 40.98N 93.05W
04/17/2026  E1.00 Inch       Monroe             IA   Public

&&

TR

Local storm report, Apr 17, 3:23 PM CDT, 39 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
323 PM CDT Fri Apr 17 2026

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

0323 PM     Hail             Bussey                  41.21N 92.89W
04/17/2026  E1.00 Inch       Marion             IA   Trained Spotter

&&

TR

Local storm report, Apr 17, 3:24 PM CDT, 38 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
324 PM CDT Fri Apr 17 2026

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

0305 PM     Hail             Tama                    41.96N 92.58W
04/17/2026  M1.75 Inch       Tama               IA   Public

            Time estimated from radar.

&&

JR/BH

Local storm report, Apr 17, 3:31 PM CDT, 31 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
331 PM CDT Fri Apr 17 2026

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

0325 PM     Hail             1 W New Sharon          41.47N 92.68W
04/17/2026  E1.00 Inch       Mahaska            IA   Public

            Report from mPING: Quarter (1.00 in.) Time
            estimated from radar.

&&

JR/BH

Local storm report, Apr 17, 3:53 PM CDT, 9 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
353 PM CDT Fri Apr 17 2026

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

0348 PM     Hail             4 N Plano               40.81N 93.05W
04/17/2026  E1.00 Inch       Appanoose          IA   911 Call Center

&&

MD

Local storm report, Apr 17, 3:56 PM CDT, 6 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
356 PM CDT Fri Apr 17 2026

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

0328 PM     Hail             New Sharon              41.47N 92.65W
04/17/2026  E1.00 Inch       Mahaska            IA   Public

            Report from mPING: Quarter (1.00 in.) Time
            estimated from radar.

&&

JR/BH

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 17, 1:52 PM CDT	Severe Thunderstorm Warning	DMX	Ringgold, Taylor	38 min
Apr 17, 1:57 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Polk, Story	48 min
Apr 17, 2:01 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Madison, Polk, Warren	29 min
Apr 17, 2:11 PM CDT	Severe Thunderstorm Warning	DMX	Bremer, Butler, Franklin, Grundy, Hardin	34 min
Apr 17, 2:25 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Mahaska, Marion, Poweshiek	50 min
Apr 17, 2:29 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Poweshiek, Story, Tama	46 min
Apr 17, 2:33 PM CDT	Tornado Warning	DMX	Jasper, Marshall, Poweshiek, Tama	42 min
Apr 17, 2:35 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Bremer, Butler	40 min
Apr 17, 2:38 PM CDT	Tornado Warning	DMX	Black Hawk, Bremer, Butler	30 min
Apr 17, 2:44 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marshall, Poweshiek	31 min
Apr 17, 2:47 PM CDT	Severe Thunderstorm Warning	DMX	Appanoose, Lucas, Mahaska, Marion, Monroe, Wayne	43 min
Apr 17, 2:57 PM CDT	Severe Thunderstorm Warning	DMX	Clarke, Lucas, Marion, Warren	11 min
Apr 17, 2:59 PM CDT	Severe Thunderstorm Warning	DMX	Decatur, Ringgold, Wayne	46 min
Apr 17, 3:03 PM CDT	Tornado Warning	DMX	Lucas, Marion, Monroe	11 min
Apr 17, 3:07 PM CDT	Severe Thunderstorm Warning	DMX	Marshall, Tama	38 min
Apr 17, 3:10 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Marion, Poweshiek	50 min
Apr 17, 3:13 PM CDT	Severe Thunderstorm Warning	DMX	Appanoose, Monroe, Wayne	17 min
Apr 17, 3:15 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Poweshiek	45 min
Apr 17, 3:16 PM CDT	Tornado Warning Tornado observed	DMX	Mahaska, Marion, Monroe	29 min
Apr 17, 3:16 PM CDT	Tornado Warning	DMX	Tama	29 min
Apr 17, 3:24 PM CDT	Tornado Warning	DMX	Poweshiek	39 min
Apr 17, 3:26 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Monroe, Wapello	64 min
Apr 17, 3:28 PM CDT	Severe Thunderstorm Warning	DMX	Appanoose, Wayne	47 min
Apr 17, 3:44 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Poweshiek, Tama	31 min
Apr 17, 4:01 PM CDT	Severe Thunderstorm Warning	DMX	Appanoose, Davis, Monroe, Wapello	44 min
Apr 17, 4:13 PM CDT	Severe Thunderstorm Warning	DMX	Appanoose, Monroe, Wayne	32 min
Apr 17, 4:17 PM CDT	Tornado Warning	DMX	Davis, Wapello	28 min
Apr 17, 4:26 PM CDT	Severe Thunderstorm Warning	DMX	Wapello	19 min
Apr 17, 4:30 PM CDT	Tornado Warning	DMX	Davis, Wapello	30 min
Apr 17, 6:16 PM CDT	Special Weather Statement	DMX	Polk	29 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2026 Every severe thunderstorm warning in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.