Alert archive / Iowa / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 377
The Storm Prediction Center issued this severe thunderstorm watch at Jul 14, 2021, 8:54 AM CDT for 19 counties in Iowa; 12 counties in Minnesota; 9 counties in Wisconsin. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 14, 2021, 8:54 AM CDT (13:54 UTC)
- Expired
- Jul 14, 2021, 1:37 PM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 40 counties
Allamakee County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clayton County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Grundy County, IA, Hardin County, IA, Howard County, IA, Mitchell County, IA, Winneshiek County, IA, Worth County, IA, Dodge County, MN, Fillmore County, MN, Freeborn County, MN, Goodhue County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Rice County, MN, Steele County, MN, Wabasha County, MN, Waseca County, MN, Winona County, MN, Buffalo County, WI, Crawford County, WI, Grant County, WI, Jackson County, WI, La Crosse County, WI, Monroe County, WI, Richland County, WI, Trempealeau County, WI, Vernon County, WI
The radar
The La Crosse radar (KARX), 113 km from the middle of the area, began a volume at 13:54 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
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 60%
- 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
- 80%
Warnings issued inside it
3 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 14, 9:06 AM CDT | Severe Thunderstorm Warning | ARX | Floyd | 39 min |
| Jul 14, 11:40 AM CDT | Severe Thunderstorm Warning | DVN | Delaware, Dubuque, Jackson | 35 min |
| Jul 14, 12:35 PM CDT | Severe Thunderstorm Warning | DVN | Dubuque, Jackson | 40 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, 1.9 hours before the alert went out and 212 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
- 2820 J/kg
- Mixed-layer CIN
- -46 J/kg
- Mixed-layer LCL
- 1084 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- -8 m²/s²
- 0-3 km storm-relative helicity
- 69 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.3
The text
As transmitted.
093
WWUS20 KWNS 141351
SEL7
SPC WW 141351
IAZ000-MNZ000-WIZ000-142000-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 377
NWS Storm Prediction Center Norman OK
855 AM CDT Wed Jul 14 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Northeast Iowa
Southeast Minnesota
Southwest Wisconsin
* Effective this Wednesday morning and afternoon from 855 AM
until 300 PM CDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph likely
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
A tornado or two possible
SUMMARY...A line of severe thunderstorms will move through the watch
area this morning and early afternoon with a risk for damaging winds
and isolated large hail.
The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 20 miles southwest of
Mason City IA to 55 miles north northeast of Dubuque IA. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU7).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
AVIATION...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
25025.
...BuntingSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 14, 7:02 AM CDT | Mesoscale Discussion | SPC | Allamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 43 more | 2 hr |
| Jul 14, 11:45 AM CDT | Mesoscale Discussion | SPC | Allamakee, Clayton, Dubuque, Jackson, Jones | 2 hr |
| Jul 14, 1:40 PM CDT | Mesoscale Discussion | SPC | Audubon, Black Hawk, Boone, Bremer, Buena Vista, Butler and 38 more | 2 hr |
| Jul 14, 2:35 PM CDT | Tornado Watch | SPC | Audubon, Benton, Black Hawk, Boone, Bremer, Buchanan and 41 more | 8 hr |
| Jul 14, 4:17 PM CDT | Mesoscale Discussion | SPC | Boone, Butler, Calhoun, Franklin, Greene, Grundy and 5 more | 58 min |
| Jul 14, 5:42 PM CDT | Mesoscale Discussion | SPC | Allamakee, Clayton, Delaware, Dubuque, Jackson, Jones | 63 min |
| Jul 14, 5:47 PM CDT | Mesoscale Discussion | SPC | Audubon, Benton, Black Hawk, Boone, Bremer, Buchanan and 29 more | 118 min |
| Jul 14, 6:13 PM CDT | Tornado Watch | SPC | Allamakee, Cedar, Clayton, Clinton, Delaware, Dubuque and 7 more | 6 hr |
| Jul 14, 2:01 PM CDT | Mesoscale Discussion | SPC | Dane, Dodge, Fond du Lac, Jefferson, Kenosha, Milwaukee and 6 more | 119 min |
Nearby
Severe Thunderstorm Watches in Iowa, 2021Severe Thunderstorm Watches in Minnesota, 2021Severe Thunderstorm Watches in Wisconsin, 2021Every severe thunderstorm 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.