Alert archive / Nebraska / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 669
The Storm Prediction Center issued this severe thunderstorm watch at Jul 21, 2011, 10:44 PM CDT for 5 counties in Iowa; Atchison County, Holt County, Nodaway County, Missouri; 25 counties in Nebraska. It was in force for 89 min.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 2011, 10:44 PM CDT (03:44 UTC)
- Expired
- Jul 22, 2011, 12:13 AM CDT
- In force
- 89 min
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 33 counties
Fremont County, IA, Mills County, IA, Montgomery County, IA, Page County, IA, Pottawattamie County, IA, Atchison County, MO, Holt County, MO, Nodaway County, MO, Adams County, NE, Butler County, NE, Cass County, NE, Clay County, NE, Douglas County, NE, Fillmore County, NE, Gage County, NE, Gosper County, NE, Hamilton County, NE, Jefferson County, NE, Johnson County, NE, Kearney County, NE, Lancaster County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Phelps County, NE, Polk County, NE, Richardson County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Thayer County, NE, York County, NE
The radar
The Grand Island radar (KUEX), 70 km from the middle of the area, began a volume at 03:45 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
- 30%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 10%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 50%
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 3.7 hours before the alert went out and 136 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
- 2480 J/kg
- Mixed-layer CIN
- -79 J/kg
- Mixed-layer LCL
- 1131 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 142 m²/s²
- 0-3 km storm-relative helicity
- 460 m²/s²
- Significant tornado parameter
- 3.8
- Supercell composite
- 43.2
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 7:09 PM CDT | Mesoscale Discussion | SPC | Adams, Appanoose, Clarke, Davis, Decatur, Des Moines and 18 more | 96 min |
| Jul 22, 3:00 PM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Black Hawk, Boone, Bremer and 61 more | 90 min |
| Jul 21, 7:10 PM CDT | Mesoscale Discussion | SPC | Cheyenne, Decatur, Gove, Greeley, Logan, Norton and 7 more | 95 min |
| Jul 21, 7:47 PM CDT | Severe Thunderstorm Watch | SPC | Cheyenne, Decatur, Ellis, Gove, Graham, Greeley and 19 more | 4 hr |
| Jul 21, 10:16 PM CDT | Mesoscale Discussion | SPC | Atchison, Brown, Clay, Cloud, Decatur, Dickinson and 37 more | 89 min |
| Jul 22, 6:22 PM CDT | Mesoscale Discussion | SPC | Arthur, Blaine, Boyd, Brown, Chase, Cherry and 17 more | 53 min |
Nearby
Severe Thunderstorm Watches in Nebraska, 2011Severe Thunderstorm Watches in Iowa, 2011Severe Thunderstorm Watches in Missouri, 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.