Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 130, NWS Des Moines, IA

December 15, 202112 counties in Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Dec 15, 2021, 6:30 PM CST for 12 counties in Iowa. It was in force for 75 min. 10 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: Dec 15, 2021, 6:30 PM CST (00:30 UTC)
Expired: Dec 15, 2021, 7:45 PM CST
In force: 75 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Damage threat: Considerable
Hail: 0.75 in
Wind: 70.0 mph

Counties Black Hawk County, IA, Bremer County, IA, Butler County, IA, Cerro Gordo County, IA, Franklin County, IA, Grundy County, IA, Hancock County, IA, Hardin County, IA, Marshall County, IA, Tama County, IA, Winnebago County, IA, Worth County, IA

The radar

The Des Moines radar (KDMX), 120 km from the middle of the area, began a volume at 00:32 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
Dec 15, 6:38 PM CST	TSTM WND GST 64	1 Nw Hampton, IA	PERSONAL WEATHER STATION.
Dec 15, 6:40 PM CST	TSTM WND DMG	1 N Swaledale, IA	DELAYED REPORT: HEAVY DAMAGE TO MACHINE SHEDS AND OUT BUILDINGS VIA SOCIAL MEDIA VIDEO.
Dec 15, 6:47 PM CST	TSTM WND DMG	2 Wsw Bristow, IA	ONE OUT BUILDING LEVELED AND ANOTHER MISSING THE NORTH WALL. TIME ESTIMATED BY RADAR.
Dec 15, 6:48 PM CST	TSTM WND DMG	1 Nnw Mason City, IA	MULTIPLE 3 INCH DIAMETER OR GREATER TREE BRANCHES DOWN. TIME ESTIMATED FROM RADAR.
Dec 15, 6:53 PM CST	TSTM WND GST 83	3 Ne Clear Lake, IA
Dec 15, 6:55 PM CST	TSTM WND DMG	Manly, IA	DAMAGE TO SHED OR OUTBUILDING EAST OF MANLY. REPORT VIA SOCIAL MEDIA. TIME ESTIMATED BY RADAR.
Dec 15, 7:15 PM CST	TSTM WND DMG	2 N Gilman, IA	SNAPPED POWER POLES. TIME ESTIMATED VIA RADAR.
Dec 15, 7:34 PM CST	TSTM WND GST 61	Waterloo Regional Airpo, IA
Dec 15, 7:36 PM CST	TSTM WND GST 62	Waterloo Regional Airpo, IA	WATERLOO MUNICIPAL AIRPORT ASOS RECORDED 54 KT WIND GUST.
Dec 15, 7:36 PM CST	NON-TSTM WND GST 62	Waterloo Regional Airpo, IA	ASOS STATION KALO WATERLOO AIRPORT.

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

The watch it was issued in

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

Issued	Product	Office	Lasted
Dec 15, 1:23 PM CST	Tornado Watch	SPC	7 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 0.5 hours before the alert went out and 218 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: 229 J/kg
Mixed-layer CIN: -358 J/kg
Mixed-layer LCL: 1061 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 433 m²/s²
0-3 km storm-relative helicity: 496 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

613 
WUUS53 KDMX 160030
SVRDMX
IAC013-017-023-033-069-075-081-083-127-171-189-195-160145-
/O.NEW.KDMX.SV.W.0130.211216T0030Z-211216T0145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
630 PM CST Wed Dec 15 2021

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northeastern Marshall County in central Iowa...
  Northeastern Hardin County in central Iowa...
  Black Hawk County in northeastern Iowa...
  Worth County in north central Iowa...
  Tama County in central Iowa...
  Bremer County in northeastern Iowa...
  Northeastern Franklin County in north central Iowa...
  Northeastern Hancock County in north central Iowa...
  Grundy County in central Iowa...
  Butler County in north central Iowa...
  Cerro Gordo County in north central Iowa...
  Eastern Winnebago County in north central Iowa...

* Until 745 PM CST.

* At 629 PM CST, severe thunderstorms were located along a line
  extending from near Easton to 9 miles north of Grinnell, moving
  northeast at 110 mph.

  HAZARD...70 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect considerable tree damage. Damage is likely to 
           mobile homes, roofs, and outbuildings.

* Severe thunderstorms will be near...
  Toledo and Tama around 635 PM CST.
  Dysart around 645 PM CST.

This includes the following highways...
 Interstate 35 between mile markers 178 and 218.
 Interstate 380 between mile markers 56 and 73.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a DANGEROUS SITUATION. These storms are producing widespread 
wind damage across northeast Iowa. SEEK SHELTER NOW inside a sturdy 
structure and stay away from windows! A Tornado Watch remains in 
effect until 800 PM CST for central, north central and northeastern 
Iowa.

&&

LAT...LON 4230 9230 4187 9230 4186 9277 4221 9295
      4221 9300 4230 9300 4291 9333 4290 9350
      4350 9368 4350 9302 4291 9302 4291 9208
      4230 9206
TIME...MOT...LOC 0029Z 237DEG 94KT 4371 9391 4187 9275 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

Cogil

3 follow-up statements

812 
WWUS53 KDMX 160043
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
643 PM CST Wed Dec 15 2021

IAC013-017-023-033-069-075-081-083-127-171-189-195-160145-
/O.CON.KDMX.SV.W.0130.000000T0000Z-211216T0145Z/
Marshall IA-Hardin IA-Black Hawk IA-Worth IA-Tama IA-Bremer IA-
Franklin IA-Hancock IA-Grundy IA-Butler IA-Cerro Gordo IA-
Winnebago IA-
643 PM CST Wed Dec 15 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM CST
FOR NORTHEASTERN MARSHALL...NORTHEASTERN HARDIN...BLACK HAWK...
WORTH...TAMA...BREMER...NORTHEASTERN FRANKLIN...NORTHEASTERN
HANCOCK...GRUNDY...BUTLER...CERRO GORDO AND EASTERN WINNEBAGO
COUNTIES...

At 643 PM CST, severe thunderstorms were located along a line
extending from near Mansfield to near Tama, moving east at 80 mph.

HAZARD...70 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect considerable tree damage. Damage is likely to mobile 
         homes, roofs, and outbuildings.

Locations impacted include...
  Northwood.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 800 PM CST for central, north
central and northeastern Iowa.

This is a DANGEROUS SITUATION. These storms are producing widespread 
wind damage across portions of northeast Iowa. SEEK SHELTER NOW 
inside a sturdy structure and stay away from windows.
 
&&

LAT...LON 4230 9230 4187 9230 4186 9277 4221 9295
      4221 9300 4230 9300 4291 9333 4290 9350
      4350 9368 4350 9302 4291 9302 4291 9208
      4230 9206
TIME...MOT...LOC 0043Z 262DEG 70KT 4353 9361 4194 9255 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

Cogil

641 
WWUS53 KDMX 160111
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
711 PM CST Wed Dec 15 2021

IAC081-189-160120-
/O.CAN.KDMX.SV.W.0130.000000T0000Z-211216T0145Z/
Hancock IA-Winnebago IA-
711 PM CST Wed Dec 15 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN HANCOCK AND
EASTERN WINNEBAGO COUNTIES IS CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 800 PM CST for central, north
central and northeastern Iowa.

LAT...LON 4230 9230 4187 9230 4186 9277 4221 9295
      4221 9300 4230 9300 4313 9338 4350 9349
      4350 9302 4291 9302 4291 9208 4230 9206
TIME...MOT...LOC 0110Z 223DEG 66KT 4381 9332 4319 9250 4222 9263 

$$

IAC013-017-023-033-069-075-083-127-171-195-160145-
/O.CON.KDMX.SV.W.0130.000000T0000Z-211216T0145Z/
Marshall IA-Hardin IA-Black Hawk IA-Worth IA-Tama IA-Bremer IA-
Franklin IA-Grundy IA-Butler IA-Cerro Gordo IA-
711 PM CST Wed Dec 15 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM CST
FOR NORTHEASTERN MARSHALL...NORTHEASTERN HARDIN...BLACK HAWK...
WORTH...TAMA...BREMER...EASTERN FRANKLIN...GRUNDY...BUTLER AND CERRO
GORDO COUNTIES...

At 710 PM CST, severe thunderstorms were located along a line
extending from near Geneva to near Elma to 7 miles south of Reinbeck,
moving northeast at 75 mph.

HAZARD...70 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect considerable tree damage. Damage is likely to mobile 
         homes, roofs, and outbuildings.

Locations impacted include...
Waterloo, Cedar Falls, Mason City, Marshalltown, Waverly, Hampton,
Grundy Center, Toledo, Northwood, Allison, Evansdale, Tama, Jesup, La
Porte City, Hudson, Sumner, Parkersburg, Denver, Traer and Reinbeck.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 800 PM CST for central, north
central and northeastern Iowa.

This is a DANGEROUS SITUATION. These storms are producing widespread 
wind damage across northeast Iowa. SEEK SHELTER NOW inside a sturdy 
structure and stay away from windows.
 
&&

LAT...LON 4230 9230 4187 9230 4186 9277 4221 9295
      4221 9300 4230 9300 4313 9338 4350 9349
      4350 9302 4291 9302 4291 9208 4230 9206
TIME...MOT...LOC 0110Z 223DEG 66KT 4381 9332 4319 9250 4222 9263 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

Cogil

991 
WWUS53 KDMX 160126
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
726 PM CST Wed Dec 15 2021

IAC033-069-195-160136-
/O.CAN.KDMX.SV.W.0130.000000T0000Z-211216T0145Z/
Worth IA-Franklin IA-Cerro Gordo IA-
726 PM CST Wed Dec 15 2021

...THE SEVERE THUNDERSTORM WARNING FOR WORTH...EASTERN FRANKLIN AND
CERRO GORDO COUNTIES IS CANCELLED...

The storms which prompted the warning have moved out of the warned 
area.  Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 800 PM CST for central, north
central and northeastern Iowa.

LAT...LON 4230 9230 4187 9230 4186 9277 4221 9295
      4221 9300 4230 9300 4238 9304 4240 9304
      4291 9280 4291 9208 4230 9206
TIME...MOT...LOC 0126Z 239DEG 55KT 4389 9305 4327 9223 4229 9236 

$$

IAC013-017-023-075-083-127-171-160145-
/O.CON.KDMX.SV.W.0130.000000T0000Z-211216T0145Z/
Marshall IA-Hardin IA-Black Hawk IA-Tama IA-Bremer IA-Grundy IA-
Butler IA-
726 PM CST Wed Dec 15 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 745 PM CST
FOR NORTHEASTERN MARSHALL...EAST CENTRAL HARDIN...BLACK HAWK...
TAMA...BREMER...GRUNDY AND BUTLER COUNTIES...

At 726 PM CST, severe thunderstorms were located along a line
extending from Blooming Prairie to 6 miles north of Jerico to 8 miles
northeast of Traer, moving northeast at 65 mph.

HAZARD...70 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect considerable tree damage. Damage is likely to mobile 
         homes, roofs, and outbuildings.

Locations impacted include...
Waterloo, Cedar Falls, Marshalltown, Waverly, Grundy Center, Toledo,
Allison, Evansdale, Tama, Jesup, La Porte City, Hudson, Sumner,
Parkersburg, Denver, Traer, Reinbeck, Clarksville, Dysart and
Tripoli.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 800 PM CST for central, north
central and northeastern Iowa.

This is a DANGEROUS SITUATION. These storms are producing widespread 
wind damage across northeast Iowa. SEEK SHELTER NOW inside a sturdy 
structure and stay away from windows.
 
&&

LAT...LON 4230 9230 4187 9230 4186 9277 4221 9295
      4221 9300 4230 9300 4238 9304 4240 9304
      4291 9280 4291 9208 4230 9206
TIME...MOT...LOC 0126Z 239DEG 55KT 4389 9305 4327 9223 4229 9236 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

Cogil

The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 15, 6:13 PM CST	Severe Thunderstorm Warning	DMX	Appanoose, Clarke, Decatur, Lucas, Marion, Monroe and 2 more	62 min
Dec 15, 6:19 PM CST	Tornado Warning	DMX	Hancock, Kossuth, Winnebago	41 min
Dec 15, 6:24 PM CST	Severe Thunderstorm Warning Considerable damage threat	DMX	Clarke, Dallas, Jasper, Lucas, Madison, Mahaska and 5 more	66 min
Dec 15, 6:37 PM CST	Tornado Warning	DMX	Butler, Cerro Gordo, Franklin	20 min
Dec 15, 6:47 PM CST	Severe Thunderstorm Warning Considerable damage threat	DMX	Grundy, Hardin, Marshall, Story	43 min
Dec 15, 7:09 PM CST	Severe Thunderstorm Warning Considerable damage threat	DMX	Appanoose, Davis, Jasper, Lucas, Mahaska, Marion and 5 more	66 min
Dec 15, 7:44 PM CST	Severe Thunderstorm Warning Considerable damage threat	DMX	Black Hawk, Bremer, Butler, Grundy, Tama	27 min
Dec 15, 11:52 PM CST	Wind Advisory	DMX	Adair, Adams, Appanoose, Audubon, Black Hawk, Boone and 45 more	6 hr

Nearby

Severe Thunderstorm Warnings in Iowa, 2021 Every severe thunderstorm warning in 2021

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.