Alert archive / Minnesota / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 460
The Storm Prediction Center issued this severe thunderstorm watch at Aug 24, 2021, 2:17 AM CDT for 40 counties in Minnesota; Pierce County, Polk County, Saint Croix County, Wisconsin. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 24, 2021, 2:17 AM CDT (07:17 UTC)
- Expired
- Aug 24, 2021, 9:00 AM CDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 43 counties
Anoka County, MN, Benton County, MN, Big Stone County, MN, Brown County, MN, Carver County, MN, Chippewa County, MN, Chisago County, MN, Dakota County, MN, Douglas County, MN, Goodhue County, MN, Grant County, MN, Hennepin County, MN, Isanti County, MN, Kanabec County, MN, Kandiyohi County, MN, Lac qui Parle County, MN, Le Sueur County, MN, McLeod County, MN, Meeker County, MN, Mille Lacs County, MN, Morrison County, MN, Nicollet County, MN, Otter Tail County, MN, Pope County, MN, Ramsey County, MN, Redwood County, MN, Renville County, MN, Rice County, MN, Scott County, MN, Sherburne County, MN, Sibley County, MN, Stearns County, MN, Stevens County, MN, Swift County, MN, Todd County, MN, Traverse County, MN, Washington County, MN, Wilkin County, MN, Wright County, MN, Yellow Medicine County, MN, Pierce County, WI, Polk County, WI, Saint Croix County, WI
The radar
The Minneapolis radar (KMPX), 124 km from the middle of the area, began a volume at 07:16 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
- 10%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
14 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 24, 2:55 AM CDT | Severe Thunderstorm Warning | MPX | Carver, Le Sueur, Scott, Sibley | 35 min |
| Aug 24, 3:28 AM CDT | Severe Thunderstorm Warning | MPX | Dakota, Scott | 32 min |
| Aug 24, 3:32 AM CDT | Severe Thunderstorm Warning | MPX | Douglas, Pope, Stevens, Swift | 43 min |
| Aug 24, 3:48 AM CDT | Severe Thunderstorm Warning | MPX | Dakota, Rice | 42 min |
| Aug 24, 3:52 AM CDT | Severe Thunderstorm Warning | MPX | Chippewa, Lac qui Parle, Swift, Yellow Medicine | 38 min |
| Aug 24, 4:08 AM CDT | Severe Thunderstorm Warning | MPX | Kandiyohi, Pope, Stearns, Stevens, Swift | 52 min |
| Aug 24, 4:44 AM CDT | Severe Thunderstorm Warning | MPX | Kandiyohi, McLeod, Meeker, Stearns | 46 min |
| Aug 24, 4:48 AM CDT | Severe Thunderstorm Warning | MPX | Chippewa, Kandiyohi, Renville | 42 min |
| Aug 24, 5:27 AM CDT | Severe Thunderstorm Warning | MPX | Kandiyohi, McLeod, Meeker, Renville, Wright | 33 min |
| Aug 24, 5:29 AM CDT | Severe Thunderstorm Warning | MPX | Meeker, Sherburne, Stearns, Wright | 46 min |
| Aug 24, 5:57 AM CDT | Severe Thunderstorm Warning | MPX | Anoka, Hennepin, Sherburne, Wright | 33 min |
| Aug 24, 5:59 AM CDT | Severe Thunderstorm Warning | MPX | Carver, McLeod, Renville, Sibley | 31 min |
| Aug 24, 6:25 AM CDT | Severe Thunderstorm Warning | MPX | Anoka, Chisago, Dakota, Hennepin, Ramsey, Washington | 35 min |
| Aug 24, 8:39 AM CDT | Severe Thunderstorm Warning | MPX | McLeod, Sibley | 21 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 00:00Z, 7.3 hours before the alert went out and 121 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
- 501 J/kg
- Mixed-layer CIN
- -147 J/kg
- Mixed-layer LCL
- 1780 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 22 m²/s²
- 0-3 km storm-relative helicity
- 16 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
514 WWUS20 KWNS 240715 SEL0 SPC WW 240715 MNZ000-WIZ000-241400- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 460 NWS Storm Prediction Center Norman OK 215 AM CDT Tue Aug 24 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central Minnesota Extreme west central Wisconsin * Effective this Tuesday morning from 215 AM until 900 AM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1 inch in diameter possible SUMMARY...An organized storm cluster will likely persist and move east-southeastward across central Minnesota through the early morning hours. The storm environment and the organized linear structure to the storms suggests that occasional damaging winds of 60-70 mph will be possible, and the strongest embedded storms may also produce isolated large hail near 1 inch diameter. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 15 miles north northwest of Ortonville MN to 50 miles east northeast of Minneapolis MN. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). 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. && OTHER WATCH INFORMATION...CONTINUE...WW 459... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 28030. ...Thompson
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 24, 1:10 AM CDT | Mesoscale Discussion | SPC | Anoka, Benton, Carver, Chippewa, Dakota, Douglas and 26 more | 95 min |
| Aug 24, 3:00 AM CDT | Mesoscale Discussion | SPC | Anoka, Benton, Big Stone, Brown, Carver, Chippewa and 35 more | 2 hr |
| Aug 24, 5:00 AM CDT | Mesoscale Discussion | SPC | Anoka, Carver, Dakota, Hennepin, Kandiyohi, McLeod and 8 more | 90 min |
| Aug 24, 6:00 AM CDT | Mesoscale Discussion | SPC | Dodge, Faribault, Fillmore, Freeborn, Houston, Mower and 5 more | 90 min |
| Aug 24, 7:10 AM CDT | Mesoscale Discussion | SPC | Blue Earth, Chisago, Dakota, Dodge, Fillmore, Freeborn and 13 more | 95 min |
| Aug 24, 12:44 PM CDT | Mesoscale Discussion | SPC | Houston | 91 min |
| Aug 24, 9:13 AM CDT | Mesoscale Discussion | SPC | Brown, Calumet, Menominee, Oconto, Outagamie, Shawano and 3 more | 62 min |
| Aug 24, 1:52 PM CDT | Severe Thunderstorm Watch | SPC | Grant | 5 hr |
| Aug 24, 3:09 PM CDT | Mesoscale Discussion | SPC | Green, Rock, Walworth | 66 min |
| Aug 24, 3:55 PM CDT | Severe Thunderstorm Watch | SPC | Green, Lafayette, Rock, Walworth | 5 hr |
Nearby
Severe 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.