Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 133, NWS Des Moines, IA

December 15, 20215 counties in Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Dec 15, 2021, 7:44 PM CST for 5 counties in Iowa. It was in force for 27 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Dec 15, 2021, 7:44 PM CST (01:44 UTC)
Expired: Dec 15, 2021, 8:11 PM CST
In force: 27 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Possible
Damage threat: Considerable
Hail: 0.75 in
Wind: 70.0 mph

Counties Black Hawk County, IA, Bremer County, IA, Butler County, IA, Grundy County, IA, Tama County, IA

The radar

The Des Moines radar (KDMX), 135 km from the middle of the area, began a volume at 01:48 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
Dec 15, 1:23 PM CST	Tornado Watch	SPC	7 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 1.7 hours before the alert went out and 171 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.

281 
WUUS53 KDMX 160144
SVRDMX
IAC013-017-023-075-171-160230-
/O.NEW.KDMX.SV.W.0133.211216T0144Z-211216T0230Z/

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

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Black Hawk County in northeastern Iowa...
  Eastern Tama County in central Iowa...
  Bremer County in northeastern Iowa...
  Northeastern Grundy County in central Iowa...
  Eastern Butler County in north central Iowa...

* Until 830 PM CST.

* At 743 PM CST, severe thunderstorms were located along a line
  extending from near Shell Rock to near Belle Plaine, moving
  northeast at 75 mph.

  HAZARD...70 mph wind gusts.

  SOURCE...Trained weather spotters.

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

* Severe thunderstorms will be near...
  Waverly around 750 PM CST.

This includes 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 4187 9246 4291 9270
      4291 9208 4230 9206
TIME...MOT...LOC 0143Z 221DEG 65KT 4275 9260 4193 9224 

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

1 follow-up statement

212 
WWUS53 KDMX 160211
SVSDMX

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

IAC013-017-023-075-171-160221-
/O.CAN.KDMX.SV.W.0133.000000T0000Z-211216T0230Z/
Black Hawk IA-Tama IA-Bremer IA-Grundy IA-Butler IA-
811 PM CST Wed Dec 15 2021

...THE SEVERE THUNDERSTORM WARNING FOR BLACK HAWK...EASTERN TAMA...
BREMER...NORTHEASTERN GRUNDY AND EASTERN BUTLER COUNTIES IS
CANCELLED...

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

LAT...LON 4230 9230 4187 9230 4187 9246 4291 9270
      4291 9208 4230 9206
TIME...MOT...LOC 0210Z 221DEG 65KT 4312 9216 4231 9180 

$$

Martin

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, 6:30 PM CST	Severe Thunderstorm Warning Considerable damage threat	DMX	Black Hawk, Bremer, Butler, Cerro Gordo, Franklin, Grundy and 6 more	75 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, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.