Alert archive / Iowa / Tornado Watches in 2021
Tornado Watch 465
The Storm Prediction Center issued this tornado watch at Aug 27, 2021, 5:15 PM CDT for 18 counties in Iowa; 8 counties in Minnesota; 11 counties in Wisconsin. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 27, 2021, 5:15 PM CDT (22:15 UTC)
- Expired
- Aug 27, 2021, 11:00 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 37 counties
Allamakee County, IA, Bremer County, IA, Butler County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clayton County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Hancock County, IA, Howard County, IA, Humboldt County, IA, Kossuth County, IA, Mitchell County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Dodge County, MN, Faribault County, MN, Fillmore County, MN, Freeborn County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Winona County, MN, Adams County, WI, Crawford County, WI, Grant County, WI, Iowa County, WI, Juneau County, WI, La Crosse County, WI, Lafayette County, WI, Monroe County, WI, Richland County, WI, Sauk County, WI, Vernon County, WI
The radar
The La Crosse radar (KARX), 110 km from the middle of the area, began a volume at 22:15 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 SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
16 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 27, 5:23 PM CDT | Tornado Warning | DMX | Cerro Gordo | 37 min |
| Aug 27, 5:25 PM CDT | Tornado Warning | DMX | Cerro Gordo | 35 min |
| Aug 27, 5:34 PM CDT | Tornado Warning | ARX | Floyd | 41 min |
| Aug 27, 6:09 PM CDT | Tornado Warning | ARX | Chickasaw, Floyd | 51 min |
| Aug 27, 6:45 PM CDT | Tornado Warning | ARX | Chickasaw, Fayette | 45 min |
| Aug 27, 6:52 PM CDT | Severe Thunderstorm Warning | ARX | Allamakee, Fayette, Winneshiek | 38 min |
| Aug 27, 7:10 PM CDT | Severe Thunderstorm Warning | DMX | Cerro Gordo, Worth | 65 min |
| Aug 27, 7:29 PM CDT | Severe Thunderstorm Warning | ARX | Allamakee, Clayton, Winneshiek | 46 min |
| Aug 27, 8:03 PM CDT | Severe Thunderstorm Warning | ARX | Clayton | 42 min |
| Aug 27, 8:09 PM CDT | Severe Thunderstorm Warning | ARX | Mitchell | 25 min |
| Aug 27, 8:15 PM CDT | Severe Thunderstorm Warning | DMX | Cerro Gordo, Worth | 30 min |
| Aug 27, 8:21 PM CDT | Flash Flood Warning | DMX | Cerro Gordo, Hancock, Winnebago, Worth | 6 hr |
| Aug 27, 8:21 PM CDT | Flash Flood Warning | MPX | Freeborn | 4 hr |
| Aug 27, 8:45 PM CDT | Flash Flood Warning | ARX | Howard, Mitchell | 9 hr |
| Aug 27, 8:48 PM CDT | Severe Thunderstorm Warning | ARX | Grant | 42 min |
| Aug 27, 8:59 PM CDT | Tornado Warning | ARX | Grant | 31 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Minneapolis, MN (KMPX), launched 12:00Z, 10.3 hours before the alert went out and 180 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
- 487 J/kg
- Mixed-layer CIN
- -63 J/kg
- Mixed-layer LCL
- 644 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km storm-relative helicity
- -9 m²/s²
- 0-3 km storm-relative helicity
- -16 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
855
WWUS20 KWNS 272213
SEL5
SPC WW 272213
IAZ000-MNZ000-WIZ000-280400-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 465
NWS Storm Prediction Center Norman OK
515 PM CDT Fri Aug 27 2021
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Northcentral and northeast Iowa
Southeast Minnesota
Southwest Wisconsin
* Effective this Friday afternoon and evening from 515 PM until
1100 PM CDT.
* Primary threats include...
A couple tornadoes possible
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
SUMMARY...Severe thunderstorms are expected to increase in coverage
across the watch area through this evening with the risk for a
couple of tornadoes, large hail and damaging downburst winds.
The tornado watch area is approximately along and 45 statute miles
north and south of a line from 40 miles north of Fort Dodge IA to 30
miles southeast of Camp Douglas WI. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU5).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.
&&
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 24030.
...BuntingSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 26, 8:03 PM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more | 7 hr |
| Aug 26, 10:45 PM CDT | Mesoscale Discussion | SPC | Bremer, Buena Vista, Butler, Calhoun, Cerro Gordo, Cherokee and 25 more | 2 hr |
| Aug 27, 1:53 PM CDT | Mesoscale Discussion | SPC | Black Hawk, Bremer, Butler, Calhoun, Cerro Gordo, Chickasaw and 18 more | 97 min |
| Aug 27, 4:01 PM CDT | Mesoscale Discussion | SPC | Allamakee, Black Hawk, Bremer, Butler, Calhoun, Cerro Gordo and 20 more | 59 min |
| Aug 27, 5:30 PM CDT | Mesoscale Discussion | SPC | Allamakee, Cerro Gordo, Chickasaw, Floyd, Howard, Winneshiek | 60 min |
| Aug 27, 6:28 PM CDT | Mesoscale Discussion | SPC | Audubon, Calhoun, Carroll, Crawford, Greene, Guthrie and 6 more | 92 min |
Nearby
Tornado Watches in Iowa, 2021Tornado Watches in Wisconsin, 2021Tornado Watches in Minnesota, 2021Every tornado watch 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.