Alert archive / North Dakota / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 666
The Storm Prediction Center issued this severe thunderstorm watch at Jul 20, 2011, 5:25 AM CDT for 11 counties in Minnesota; 24 counties in North Dakota. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 20, 2011, 5:25 AM CDT (10:25 UTC)
- Expired
- Jul 20, 2011, 11:50 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 35 counties
Beltrami County, MN, Clearwater County, MN, Kittson County, MN, Lake of the Woods County, MN, Mahnomen County, MN, Marshall County, MN, Norman County, MN, Pennington County, MN, Polk County, MN, Red Lake County, MN, Roseau County, MN, Benson County, ND, Bottineau County, ND, Burke County, ND, Cavalier County, ND, Eddy County, ND, Foster County, ND, Grand Forks County, ND, Griggs County, ND, McHenry County, ND, McLean County, ND, Mountrail County, ND, Nelson County, ND, Pembina County, ND, Pierce County, ND, Ramsey County, ND, Renville County, ND, Rolette County, ND, Sheridan County, ND, Steele County, ND, Towner County, ND, Traill County, ND, Walsh County, ND, Ward County, ND, Wells County, ND
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
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
17 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 5:30 AM CDT | Tornado Warning | FGF | Ramsey, Walsh | 45 min |
| Jul 20, 5:41 AM CDT | Severe Thunderstorm Warning | FGF | Pembina, Walsh | 34 min |
| Jul 20, 5:43 AM CDT | Severe Thunderstorm Warning | BIS | McHenry, McLean, Sheridan, Ward | 62 min |
| Jul 20, 6:07 AM CDT | Tornado Warning | FGF | Grand Forks, Nelson, Walsh | 38 min |
| Jul 20, 6:22 AM CDT | Severe Thunderstorm Warning | BIS | McHenry, Pierce, Sheridan, Wells | 53 min |
| Jul 20, 6:28 AM CDT | Severe Thunderstorm Warning | FGF | Benson, Eddy, Ramsey, Towner | 62 min |
| Jul 20, 6:34 AM CDT | Tornado Warning | BIS | Pierce | 26 min |
| Jul 20, 6:40 AM CDT | Severe Thunderstorm Warning | FGF | Marshall, Polk | 50 min |
| Jul 20, 7:05 AM CDT | Severe Thunderstorm Warning | BIS | Pierce, Rolette | 40 min |
| Jul 20, 7:21 AM CDT | Severe Thunderstorm Warning | FGF | Benson, Cavalier, Ramsey, Towner, Walsh | 54 min |
| Jul 20, 7:24 AM CDT | Severe Thunderstorm Warning | FGF | Kittson, Marshall, Roseau | 51 min |
| Jul 20, 7:41 AM CDT | Severe Thunderstorm Warning | FGF | Kittson, Roseau | 34 min |
| Jul 20, 7:59 AM CDT | Severe Thunderstorm Warning | FGF | Beltrami, Kittson, Lake of the Woods, Marshall, Roseau | 61 min |
| Jul 20, 8:08 AM CDT | Severe Thunderstorm Warning | FGF | Kittson, Marshall | 67 min |
| Jul 20, 8:27 AM CDT | Tornado Warning | FGF | Roseau | 48 min |
| Jul 20, 8:58 AM CDT | Severe Thunderstorm Warning | FGF | Lake of the Woods, Roseau | 47 min |
| Jul 20, 9:16 AM CDT | Severe Thunderstorm Warning | FGF | Lake of the Woods, Roseau | 44 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
Bismarck Municip, ND (KBIS), launched 00:00Z, 10.4 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.
- Mixed-layer CAPE
- 5088 J/kg
- Mixed-layer CIN
- -73 J/kg
- Mixed-layer LCL
- 1472 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- -4 m²/s²
- 0-3 km storm-relative helicity
- 95 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 5.9
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 5:02 AM CDT | Mesoscale Discussion | SPC | Clay, Clearwater, Kittson, Mahnomen, Marshall, Norman and 4 more | 88 min |
| Jul 20, 10:43 AM CDT | Mesoscale Discussion | SPC | Beltrami, Clearwater, Kittson, Marshall, Pennington, Polk and 2 more | 62 min |
| Jul 20, 6:55 PM CDT | Mesoscale Discussion | SPC | Aitkin, Carlton, Cass, Cook, Itasca, Koochiching and 2 more | 95 min |
Nearby
Severe Thunderstorm Watches in North Dakota, 2011Severe Thunderstorm Watches in Minnesota, 2011Every severe thunderstorm watch in 2011
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.