Alert archive / North Dakota / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 820
The Storm Prediction Center issued this severe thunderstorm watch at Sep 1, 2011, 12:48 AM CDT for 11 counties in Minnesota; 12 counties in North Dakota. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 1, 2011, 12:48 AM CDT (05:48 UTC)
- Expired
- Sep 1, 2011, 7:00 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 65 kt
All 23 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, Cavalier County, ND, Eddy County, ND, Grand Forks County, ND, Griggs County, ND, Nelson County, ND, Pembina County, ND, Ramsey County, ND, Steele County, ND, Towner County, ND, Traill County, ND, Walsh County, ND
The radar
The Fargo/Grand Forks radar (KMVX), 87 km from the middle of the area, began a volume at 05:48 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.
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
- 50%
- One or more gusts of 65 knots or more
- 30%
- 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
- 70%
Warnings issued inside it
6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 1, 1:07 AM CDT | Severe Thunderstorm Warning | FGF | Cavalier, Towner | 53 min |
| Sep 1, 1:23 AM CDT | Severe Thunderstorm Warning | FGF | Benson, Eddy, Nelson, Ramsey, Towner, Walsh | 67 min |
| Sep 1, 1:57 AM CDT | Severe Thunderstorm Warning | FGF | Cavalier, Pembina | 63 min |
| Sep 1, 2:19 AM CDT | Severe Thunderstorm Warning | FGF | Grand Forks, Nelson, Walsh | 41 min |
| Sep 1, 2:49 AM CDT | Severe Thunderstorm Warning | FGF | Kittson, Marshall, Pennington, Polk, Roseau | 56 min |
| Sep 1, 3:41 AM CDT | Severe Thunderstorm Warning | FGF | Beltrami, Lake of the Woods, Marshall, Pennington, Polk, Red Lake and 1 more | 64 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
International Fa, MN (KINL), launched 00:00Z, 5.8 hours before the alert went out and 295 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
- 4 J/kg
- Mixed-layer CIN
- -6 J/kg
- Mixed-layer LCL
- 463 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 59 m²/s²
- 0-3 km storm-relative helicity
- 145 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 1, 3:40 AM CDT | Mesoscale Discussion | SPC | Beltrami, Clearwater, Itasca, Kittson, Koochiching, Lake of the Woods and 7 more | 65 min |
| Sep 1, 6:39 AM CDT | Mesoscale Discussion | SPC | Beltrami, Cass, Clearwater, Hubbard, Itasca, Koochiching and 1 more | 36 min |
| Aug 31, 8:24 PM CDT | Mesoscale Discussion | SPC | Billings, Bottineau, Burke, Divide, Dunn, Golden Valley and 10 more | 66 min |
| Aug 31, 8:53 PM CDT | Severe Thunderstorm Watch | SPC | Billings, Bottineau, Burke, Burleigh, Divide, Dunn and 19 more | 7 hr |
| Aug 31, 10:54 PM CDT | Mesoscale Discussion | SPC | Bottineau, Burke, Burleigh, Hettinger, McHenry, McLean and 9 more | 96 min |
| Sep 1, 12:02 AM CDT | Mesoscale Discussion | SPC | Benson, Bottineau, Burleigh, Eddy, Foster, Griggs and 14 more | 58 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; radar from the NEXRAD Level II archive.