Alert archive / Iowa / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 90, NWS Des Moines, IA
NWS Des Moines, IA issued this severe thunderstorm warning at Aug 20, 2021, 9:46 PM CDT for Hamilton County, Webster County, Wright County, Iowa. It was in force for 44 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
- Aug 20, 2021, 9:46 PM CDT (02:46 UTC)
- Expired
- Aug 20, 2021, 10:30 PM CDT
- In force
- 44 min
- Issued by
- NWS Des Moines, IA
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Hamilton County, IA, Webster County, IA, Wright County, IA
The radar
The Des Moines radar (KDMX), 85 km from the middle of the area, began a volume at 02:48 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 |
|---|---|---|---|
| Aug 20, 3:58 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 2.8 hours before the alert went out and 251 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.
- Mixed-layer CAPE
- 3521 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 877 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km storm-relative helicity
- 107 m²/s²
- 0-3 km storm-relative helicity
- 153 m²/s²
- Significant tornado parameter
- 2.5
- Supercell composite
- 13.7
The text
As transmitted.
769 WUUS53 KDMX 210246 SVRDMX IAC079-187-197-210330- /O.NEW.KDMX.SV.W.0090.210821T0246Z-210821T0330Z/ BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Des Moines IA 946 PM CDT Fri Aug 20 2021 The National Weather Service in Des Moines has issued a * Severe Thunderstorm Warning for... East central Webster County in central Iowa... Southern Wright County in north central Iowa... Northern Hamilton County in central Iowa... * Until 1030 PM CDT. * At 946 PM CDT, a severe thunderstorm was located near Webster City, moving east at 35 mph. HAZARD...60 mph wind gusts. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. * This severe thunderstorm will be near... Webster City around 955 PM CDT. Other locations in the path of this severe thunderstorm include Big Wall Lake. This includes Interstate 35 between mile markers 140 and 154. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. Torrential rainfall is occurring with this storm, and may lead to flash flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4239 9397 4260 9399 4269 9350 4240 9350 TIME...MOT...LOC 0246Z 259DEG 32KT 4251 9391 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...<.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$ Cogil
2 follow-up statements
382 WWUS53 KDMX 210303 SVSDMX Severe Weather Statement National Weather Service Des Moines IA 1003 PM CDT Fri Aug 20 2021 IAC079-187-197-210330- /O.CON.KDMX.SV.W.0090.000000T0000Z-210821T0330Z/ Webster IA-Wright IA-Hamilton IA- 1003 PM CDT Fri Aug 20 2021 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1030 PM CDT FOR EAST CENTRAL WEBSTER...SOUTHERN WRIGHT AND NORTHERN HAMILTON COUNTIES... At 1003 PM CDT, a severe thunderstorm was located near Big Wall Lake, or 9 miles northeast of Webster City, moving east at 40 mph. HAZARD...60 mph wind gusts. SOURCE...Radar indicated. IMPACT...Expect damage to roofs, siding, and trees. This severe thunderstorm will remain over mainly rural areas of east central Webster, southern Wright and northern Hamilton Counties, including the following locations... Blairsburg, Williams, Webster City Municipal Airport, Dows, Woolstock, Kamrar, Duncombe and Brushy Creek St Recreation Area. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. Torrential rainfall is occurring with this storm, and may lead to flash flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4239 9397 4260 9399 4269 9350 4240 9350 TIME...MOT...LOC 0303Z 258DEG 33KT 4254 9366 HAIL THREAT...RADAR INDICATED MAX HAIL SIZE...<.75 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...60 MPH $$ Cogil
521
WWUS53 KDMX 210329
SVSDMX
Severe Weather Statement
National Weather Service Des Moines IA
1029 PM CDT Fri Aug 20 2021
IAC079-187-197-210339-
/O.EXP.KDMX.SV.W.0090.000000T0000Z-210821T0330Z/
Webster IA-Wright IA-Hamilton IA-
1029 PM CDT Fri Aug 20 2021
...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL WEBSTER...
SOUTHERN WRIGHT AND NORTHERN HAMILTON COUNTIES WILL EXPIRE AT 1030 PM
CDT...
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire. However gusty
winds and heavy rain are still possible with this thunderstorm.
LAT...LON 4239 9397 4260 9399 4269 9350 4240 9350
TIME...MOT...LOC 0329Z 259DEG 32KT 4258 9336
$$
CogilThe office that day
Everything else NWS Des Moines, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 20, 8:03 PM CDT | Special Weather Statement | DMX | Crawford | 27 min |
| Aug 20, 8:18 PM CDT | Special Weather Statement | DMX | Hancock, Winnebago, Wright | 42 min |
| Aug 20, 9:05 PM CDT | Severe Thunderstorm Warning | DMX | Franklin, Wright | 55 min |
| Aug 20, 9:35 PM CDT | Special Weather Statement | DMX | Guthrie | 25 min |
| Aug 20, 10:10 PM CDT | Special Weather Statement | DMX | Guthrie | 35 min |
| Aug 20, 10:42 PM CDT | Special Weather Statement | DMX | Boone | 33 min |
| Aug 21, 12:45 AM CDT | Special Weather Statement | DMX | Jasper | 45 min |
Nearby
Severe Thunderstorm Warnings in Iowa, 2021Every 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.