Alert archive / Iowa / Severe Thunderstorm Warnings in 2024

Severe Thunderstorm Warning 113, NWS Des Moines, IA

May 21, 20248 counties in Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 21, 2024, 4:25 PM CDT for 8 counties in Iowa. It was in force for 50 min. 5 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: May 21, 2024, 4:25 PM CDT (21:25 UTC)
Expired: May 21, 2024, 5:15 PM CDT
In force: 50 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Boone County, IA, Franklin County, IA, Grundy County, IA, Hamilton County, IA, Hardin County, IA, Marshall County, IA, Story County, IA, Wright County, IA

The radar

The Des Moines radar (KDMX), 73 km from the middle of the area, began a volume at 21:25 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.

What was reported inside it

Time	Report	Where	Remark
May 21, 4:34 PM CDT	TSTM WND DMG	Blairsburg, IA	Very strong winds and power outage reported.
May 21, 4:51 PM CDT	HAIL 1	Alden, IA	Report from mPING: Quarter.
May 21, 5:06 PM CDT	TSTM WND GST 60	Hubbard, IA	Town without power.
May 21, 5:10 PM CDT	TSTM WND GST 64	2 Sw Hampton, IA
May 21, 5:13 PM CDT	TSTM WND DMG	2 Wnw New Providence, IA	Emergency manager reported damage to farm outbuildings east of Hubbard. Time estimated with radar.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched 5 storm reports to this severe thunderstorm warning; the first came 9 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

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

Issued	Product	Office	Lasted
May 21, 1:14 PM CDT	Tornado Watch PDS	SPC	8 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 9.4 hours before the alert went out and 259 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: 1292 J/kg
Mixed-layer CIN: -75 J/kg
Mixed-layer LCL: 1074 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 63 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.4

Open this sounding in Storm Lab

The text

As transmitted.

454 
WUUS53 KDMX 212125
SVRDMX
IAC015-069-075-079-083-127-169-197-212215-
/O.NEW.KDMX.SV.W.0113.240521T2125Z-240521T2215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
425 PM CDT Tue May 21 2024

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northern Story County in central Iowa...
  Northwestern Marshall County in central Iowa...
  Hardin County in central Iowa...
  Southeastern Wright County in north central Iowa...
  Southern Franklin County in north central Iowa...
  Southwestern Grundy County in central Iowa...
  Northeastern Boone County in central Iowa...
  Hamilton County in central Iowa...

* Until 515 PM CDT.

* At 425 PM CDT, a severe thunderstorm was located near Big Wall
  Lake, or 11 miles southeast of Clarion, moving northeast at 60 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Webster City, Iowa Falls, Hampton, Eldora, Story City, Ackley,
  Roland, Jewell Junction, Gilbert, Big Wall Lake, Hubbard, Alden,
  Zearing, Radcliffe, Dows, Ellsworth, Union, Williams, McCallsburg,
  and Steamboat Rock.

This includes Interstate 35 between mile markers 120 and 165.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

A Tornado Watch remains in effect until 900 PM CDT for central and
north central Iowa.

&&

LAT...LON 4208 9373 4261 9382 4281 9315 4222 9290
TIME...MOT...LOC 2125Z 234DEG 50KT 4262 9357 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Donavon

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 May 21, 1:42 PM CDT, 2 hours 43 minutes earlier. Its key messages:

Take action for ALL weather warnings this afternoon with tornadoes, damaging wind gusts, and large hail all possible
Renewed or prolonged flooding possible with rain that falls this afternoon with rivers rising

Area forecast discussion, May 21, 1:42 PM CDT, 2 hours 43 minutes before

Area Forecast Discussion
National Weather Service Des Moines IA
142 PM CDT Tue May 21 2024

.KEY MESSAGES...
- Take action for ALL weather warnings this afternoon with
  tornadoes, damaging wind gusts, and large hail all possible
- Renewed or prolonged flooding possible with rain that falls
  this afternoon with rivers rising

&&

.DISCUSSION...
Issued at 142 PM CDT Tue May 21 2024

Already one round of heavy rainfall moved through the state last
night with 3 to 5 inches of rainfall in some areas with isolated
higher amounts that led to flash flooding. Severe storms also moved
over southern and parts of central Iowa in the morning hours. As a
shortwave trough lifts northeastward and negatively tilts this
afternoon, latest Warn on Forecast System (WoFS) is showing
good airmass recovery with dewpoints rising 5 or so degrees
ahead of a surface triple point. Low level kinematics are
already strong and mid-levels are increasing as well. As the
airmass recovers, WoFS shows strong instability with MLCAPE
growing above 1500 J/kg and very favorable 0-500m and 0-1km SRH
ahead of it as well. Hodographs show a bit more linear
depiction, but initially they may be able to remain curved in
the low levels. Therefore, concern and confidence remain high of
rotating storms capable of tornadoes, including a few strong
given the Particularly Dangerous Situation Tornado Watch issued
earlier, damaging wind gusts including the potential of a few
intense wind gusts (greater than 75 mph), and large hail larger
than golf ball size. The hail size can be greater with rotating
storms as hailstones recycle in the updraft. Rainfall with
these storms of 1 to 2 inches will be possible and could cause
new flash flooding or prolong or renew flooding with rivers
rising as well from the recent and future rainfall. Storms will
move quickly through our area this afternoon and be largely east
of a Waterloo to Ottumwa line by around 7pm

As we move into this evening, we will enter a several day period of
drier conditions, which will be welcome for saturated soils and
swollen streams. While river flooding will be peaking mid to
late this week, no substantial rainfall is forecast until
Thursday night into Friday. This is when the next shortwave
trough will approach and pass north of the region and bring
thunderstorms through the state. The timing may mitigate a wider
severe risk, but instability and shear may be sufficient for a
few strong to severe storms.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1235 PM CDT Tue May 21 2024

Main concern is severe thunderstorms that may have large hail
and damaging wind gusts this afternoon. TEMPO lines are for best
timing of storms with impacts that may need more limited as the
storms move through than currently shown. Winds are gusty from
the southeast early this afternoon, but will stay gusty as they
become from the northwest behind the storms. A return to VFR
conditions is forecast into tonight.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 7 PM CDT this evening for IAZ004>007-015>017-
023>028-033>039-044>050-057>062-070>075-081>083-092.

&&

DISCUSSION...Ansorge
AVIATION...Ansorge

Hazardous weather outlook, May 21, 2:15 PM CDT, 2 hours 10 minutes before

Hazardous Weather Outlook
National Weather Service Des Moines IA
215 PM CDT Tue May 21 2024

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-221915-
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-
215 PM CDT Tue May 21 2024

This Hazardous Weather Outlook is for portions of central Iowa,
north central Iowa, northeast Iowa, northwest Iowa, south central
Iowa, southeast Iowa, southwest Iowa, and west central Iowa.

.DAY ONE...This Afternoon and Tonight

A cold front that will be moving eastward across the state of Iowa
to generate a line of strong-severe storms during the afternoon
and evening hours with tornadoes, damaging winds, flash flooding,
and large hail all possible with the strongest storms. The worst
of the storms will be primarily during the 3 pm to 9 pm timeframe.
Winds could gust over 40 mph at times this evening as the storms
move off to the east.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Additional thunderstorm chances return at times Friday and
through the weekend. The severe weather potential for these days
will be better determined in the coming days.

.SPOTTER INFORMATION STATEMENT...

In the hours before

Local storm report, May 21, 4:11 PM CDT, 14 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
411 PM CDT Tue May 21 2024

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

0355 PM     Tstm Wnd Gst     2 WSW Algona            43.07N 94.27W
05/21/2024  M70 MPH          Kossuth            IA   AWOS

            AWOS station KAXA Algona Airport.

&&

JC/CH

Local storm report, May 21, 4:15 PM CDT, 10 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
415 PM CDT Tue May 21 2024

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

0409 PM     Tstm Wnd Gst     2 NNE Fort Dodge        42.53N 94.17W
05/21/2024  M52 MPH          Webster            IA   AWOS

            AWOS station KFOD Fort Dodge Airport.

&&

JC/CH

Local storm report, May 21, 4:17 PM CDT, 8 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
417 PM CDT Tue May 21 2024

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

0407 PM     Flood            2 NNW Ferguson          41.97N 92.88W
05/21/2024                   Marshall           IA   Emergency Mngr

            Several roads closed due to water over the
            roads across the county. Several bridges
            impassable due to flooding. A couple
            landslides due to the flooding.

&&

JAZ

Local storm report, May 21, 4:19 PM CDT, 6 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
419 PM CDT Tue May 21 2024

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

0340 PM     Tornado          3 E Fontanelle          41.30N 94.51W
05/21/2024                   Adair              IA   Public

            Reported by Trained Spotter.

&&

JC/CH

Local storm report, May 21, 4:20 PM CDT, 5 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
420 PM CDT Tue May 21 2024

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

0418 PM     Hail             Minburn                 41.76N 94.03W
05/21/2024  E0.88 Inch       Dallas             IA   Amateur Radio

&&

Local storm report, May 21, 4:21 PM CDT, 4 minutes before

Preliminary Local Storm Report
National Weather Service Des Moines IA
421 PM CDT Tue May 21 2024

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

0412 PM     Hail             Dana                    42.11N 94.24W
05/21/2024  M0.75 Inch       Greene             IA   Public

            Report from mPING Penny sized hail.

&&

JC/CH

The office that day

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

Issued	Product	Office	Counties	Lasted
May 20, 8:25 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Palo Alto, Pocahontas	50 min
May 20, 8:48 PM CDT	Severe Thunderstorm Warning	DMX	Hancock, Kossuth, Winnebago	42 min
May 20, 9:12 PM CDT	River Flood Watch	DMX	Black Hawk	24 hr
May 20, 9:13 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Humboldt, Kossuth, Palo Alto, Pocahontas	37 min
May 20, 9:30 PM CDT	Severe Thunderstorm Warning	DMX	Hancock, Winnebago, Worth	22 min
May 20, 10:20 PM CDT	Special Weather Statement	DMX	Hancock	25 min
May 20, 10:35 PM CDT	Severe Thunderstorm Warning	DMX	Kossuth	25 min
May 20, 10:40 PM CDT	Special Weather Statement	DMX	Palo Alto, Pocahontas	35 min
May 20, 11:02 PM CDT	Severe Thunderstorm Warning	DMX	Palo Alto, Pocahontas	28 min
May 20, 11:16 PM CDT	Flash Flood Warning	DMX	Hancock, Kossuth, Winnebago	6 hr
May 20, 11:30 PM CDT	Special Weather Statement	DMX	Carroll	30 min
May 20, 11:34 PM CDT	Special Weather Statement	DMX	Guthrie	26 min
May 20, 11:58 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Calhoun, Carroll, Dallas, Greene, Guthrie and 2 more	36 min
May 21, 12:06 AM CDT	Special Weather Statement	DMX	Pocahontas	24 min
May 21, 12:10 AM CDT	Special Weather Statement	DMX	Hancock	35 min
May 21, 1:09 AM CDT	Severe Thunderstorm Warning	DMX	Audubon, Carroll, Crawford	66 min
May 21, 1:20 AM CDT	Severe Thunderstorm Warning	DMX	Jasper, Polk	40 min
May 21, 2:15 AM CDT	Special Weather Statement	DMX	Audubon, Guthrie	60 min
May 21, 2:32 AM CDT	Special Weather Statement	DMX	Black Hawk, Tama	28 min
May 21, 2:38 AM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Butler, Grundy, Hardin	37 min
May 21, 2:56 AM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Bremer, Butler	49 min
May 21, 3:09 AM CDT	Flash Flood Warning	DMX	Butler, Franklin, Grundy, Hardin, Wright	8 hr
May 21, 3:22 AM CDT	Severe Thunderstorm Warning	DMX	Carroll, Crawford, Sac	38 min
May 21, 3:26 AM CDT	Flash Flood Warning	DMX	Adair, Audubon, Cass, Guthrie	8 hr
May 21, 4:12 AM CDT	Special Weather Statement	DMX	Polk	33 min
May 21, 4:22 AM CDT	Flash Flood Warning	DMX	Boone, Dallas, Greene, Guthrie, Jasper, Marshall and 2 more	7 hr
May 21, 5:09 AM CDT	Areal Flood Warning	DMX	Hancock, Kossuth, Winnebago	14 hr
May 21, 5:25 AM CDT	Severe Thunderstorm Warning	DMX	Poweshiek, Tama	50 min
May 21, 5:51 AM CDT	Severe Thunderstorm Warning	DMX	Jasper, Poweshiek, Tama	39 min
May 21, 6:18 AM CDT	Severe Thunderstorm Warning	DMX	Poweshiek, Tama	42 min
May 21, 6:26 AM CDT	Flash Flood Warning	DMX	Jasper, Marshall, Poweshiek, Tama	5 hr
May 21, 6:28 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Carroll, Crawford, Sac	47 min
May 21, 6:51 AM CDT	Severe Thunderstorm Warning	DMX	Audubon, Carroll, Cass, Crawford, Guthrie	54 min
May 21, 7:07 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Cass	23 min
May 21, 7:24 AM CDT	Tornado Warning	DMX	Adair, Cass	36 min
May 21, 7:29 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Adair, Audubon, Cass, Guthrie	46 min
May 21, 7:35 AM CDT	Severe Thunderstorm Warning	DMX	Adair, Adams, Cass, Taylor	40 min
May 21, 8:05 AM CDT	Severe Thunderstorm Warning	DMX	Adair, Dallas, Guthrie, Madison	55 min
May 21, 8:41 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Dallas, Madison, Polk, Warren	64 min
May 21, 8:57 AM CDT	Flash Flood Warning	DMX	Black Hawk, Bremer, Grundy, Hardin, Marshall, Tama	2 hr
May 21, 9:26 AM CDT	Severe Thunderstorm Warning	DMX	Jasper, Mahaska, Marion, Marshall, Polk, Poweshiek and 2 more	64 min
May 21, 10:09 AM CDT	River Flood Warning	DMX	Cass	15 hr
May 21, 11:14 AM CDT	River Flood Watch	DMX	Polk	4 days
May 21, 11:14 AM CDT	River Flood Watch	DMX	Webster	9 hr
May 21, 11:14 AM CDT	River Flood Watch	DMX	Polk	5 days
May 21, 11:14 AM CDT	River Flood Watch	DMX	Dallas, Greene	4 days
May 21, 11:14 AM CDT	River Flood Watch	DMX	Boone, Hamilton, Webster	47 hr
May 21, 11:14 AM CDT	River Flood Warning	DMX	Tama	8 days
May 21, 11:14 AM CDT	Severe Thunderstorm Warning	DMX	Jasper, Mahaska, Marion, Poweshiek	46 min
May 21, 11:16 AM CDT	Areal Flood Warning	DMX	Black Hawk, Bremer, Butler, Franklin, Grundy, Hardin and 6 more	24 hr
May 21, 11:54 AM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Poweshiek	21 min
May 21, 1:38 PM CDT	Severe Thunderstorm Warning	DMX	Crawford	52 min
May 21, 2:18 PM CDT	Severe Thunderstorm Warning	DMX	Sac	29 min
May 21, 2:28 PM CDT	Severe Thunderstorm Warning	DMX	Adams, Audubon, Cass	62 min
May 21, 2:30 PM CDT	Severe Thunderstorm Warning	DMX	Audubon, Calhoun, Carroll, Crawford, Sac	45 min
May 21, 2:52 PM CDT	Tornado Warning	DMX	Adams, Cass	18 min
May 21, 2:55 PM CDT	Tornado Warning	DMX	Adair, Adams, Cass, Union	50 min
May 21, 2:57 PM CDT	Flash Flood Warning	DMX	Adair, Audubon, Carroll, Cass, Crawford, Greene and 1 more	6 hr
May 21, 3:07 PM CDT	Tornado Warning	DMX	Adair, Adams, Madison, Taylor, Union	53 min
May 21, 3:11 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	Audubon, Boone, Calhoun, Carroll, Greene, Guthrie and 1 more	49 min
May 21, 3:13 PM CDT	Tornado Warning	DMX	Audubon, Cass, Greene, Guthrie	22 min
May 21, 3:20 PM CDT	River Flood Warning	DMX	Polk	7 hr
May 21, 3:26 PM CDT	River Flood Warning	DMX	Polk	4 days
May 21, 3:26 PM CDT	River Flood Warning	DMX	Polk	4 days
May 21, 3:26 PM CDT	Tornado Warning Tornado observed	DMX	Adair, Adams, Madison, Union	49 min
May 21, 3:31 PM CDT	Severe Thunderstorm Warning Destructive damage threat	DMX	Boone, Greene, Hamilton, Webster, Wright	44 min
May 21, 3:33 PM CDT	Tornado Warning	DMX	Ringgold, Taylor, Union	42 min
May 21, 3:35 PM CDT	Tornado Warning Tornado observedConsiderable damage threat	DMX	Adair, Dallas, Guthrie, Madison	40 min
May 21, 3:40 PM CDT	Tornado Warning Tornado observed	DMX	Adair, Adams, Dallas, Madison, Ringgold, Union	50 min
May 21, 3:55 PM CDT	Tornado Warning	DMX	Clarke, Madison, Ringgold, Union, Warren	50 min
May 21, 3:58 PM CDT	Tornado Warning	DMX	Clarke, Decatur, Lucas, Ringgold, Union, Warren	47 min
May 21, 4:01 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Greene, Guthrie, Hamilton, Webster	44 min
May 21, 4:03 PM CDT	Tornado Warning	DMX	Boone, Hamilton, Webster	42 min
May 21, 4:11 PM CDT	Severe Thunderstorm Warning	DMX	Boone, Clarke, Dallas, Decatur, Lucas, Madison and 4 more	64 min
May 21, 4:11 PM CDT	Severe Thunderstorm Warning	DMX	Hancock, Kossuth, Winnebago, Worth	49 min
May 21, 4:15 PM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Franklin, Hancock, Worth, Wright	45 min
May 21, 4:19 PM CDT	Tornado Warning	DMX	Boone, Dallas, Polk, Story	41 min
May 21, 4:30 PM CDT	Tornado Warning	DMX	Jasper, Madison, Polk, Warren	45 min
May 21, 4:43 PM CDT	Severe Thunderstorm Warning	DMX	Grundy, Hardin, Jasper, Marion, Marshall, Polk and 2 more	47 min
May 21, 4:46 PM CDT	Tornado Warning	DMX	Franklin, Grundy, Hamilton, Hardin	17 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2024 Every severe thunderstorm warning in 2024

Sources

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