Alert archive / Nebraska / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 621
The Storm Prediction Center issued this severe thunderstorm watch at Jul 10, 2011, 10:57 PM CDT for 6 counties in Iowa; 20 counties in Nebraska. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 10, 2011, 10:57 PM CDT (03:57 UTC)
- Expired
- Jul 11, 2011, 2:35 AM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 26 counties
Harrison County, IA, Mills County, IA, Monona County, IA, Montgomery County, IA, Pottawattamie County, IA, Shelby County, IA, Antelope County, NE, Boone County, NE, Burt County, NE, Butler County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Dodge County, NE, Douglas County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Platte County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE
The radar
The Omaha radar (KOAX), 119 km from the middle of the area, began a volume at 03:57 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
- 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
6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 10, 11:05 PM CDT | Severe Thunderstorm Warning | OAX | Antelope, Boone, Madison, Platte | 25 min |
| Jul 10, 11:24 PM CDT | Severe Thunderstorm Warning | OAX | Butler, Colfax, Lancaster, Platte, Saunders, Seward | 51 min |
| Jul 10, 11:29 PM CDT | Severe Thunderstorm Warning | OAX | Antelope, Boone, Colfax, Madison, Pierce, Platte and 1 more | 46 min |
| Jul 10, 11:56 PM CDT | Severe Thunderstorm Warning | OAX | Antelope, Cedar, Cuming, Knox, Madison, Pierce and 3 more | 49 min |
| Jul 11, 12:11 AM CDT | Severe Thunderstorm Warning | OAX | Burt, Colfax, Cuming, Dodge, Saunders, Stanton and 2 more | 37 min |
| Jul 11, 12:25 AM CDT | Severe Thunderstorm Warning | OAX | Cedar, Knox | 35 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
Omaha, NE (KOAX), launched 00:00Z, 4.0 hours before the alert went out and 119 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
- 4133 J/kg
- Mixed-layer CIN
- -75 J/kg
- Mixed-layer LCL
- 1304 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 25 m²/s²
- 0-3 km storm-relative helicity
- 62 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 3.7
The text
As transmitted, in the capitals the NWS used until 2016.
271
WWUS20 KWNS 110358
SEL1
SPC WW 110358
NEZ000-111000-
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 621
NWS STORM PREDICTION CENTER NORMAN OK
1055 PM CDT SUN JUL 10 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
EASTERN NEBRASKA
EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 1055 PM UNTIL
500 AM CDT.
HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75
STATUTE MILES EAST AND WEST OF A LINE FROM 25 MILES EAST
SOUTHEAST OF GRAND ISLAND NEBRASKA TO 35 MILES NORTHEAST OF
NORFOLK NEBRASKA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).
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 618...WW 619...WW 620...
DISCUSSION...BOWING MCS OVER CNTRL NEB IS EXPECTED TO CONTINUE
LIFTING NEWD ACROSS WATCH AREA WITH ADDITIONAL DEVELOPMENT LIKELY
ALONG THE ERN FLANK OF SYSTEM WITHIN EXIT REGION OF
STRENGTHENING...NOCTURNAL LLJ. 00Z OAX SOUNDING SHOWED THE PRESENCE
OF A VERY UNSTABLE ENVIRONMENT WITH MUCAPE UPWARDS OF 5000-7000
J/KG...WHICH WILL SERVE TO ENHANCE ROBUST UPDRAFT DEVELOPMENT ALONG
THE LEADING EDGE OF SYSTEM COLD POOL. DAMAGING WINDS WILL BE THE
PRIMARY HAZARD...THOUGH SOME LARGE HAIL WILL ALSO BE POSSIBLE.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. MEAN STORM
MOTION VECTOR 24035.
...MEADSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 10, 7:51 PM CDT | Mesoscale Discussion | SPC | Allamakee, Howard, Mitchell, Winneshiek | 84 min |
| Jul 10, 9:53 PM CDT | Mesoscale Discussion | SPC | Allamakee, Cerro Gordo, Chickasaw, Dickinson, Emmet, Floyd and 9 more | 67 min |
| Jul 10, 10:10 PM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Black Hawk, Bremer, Butler, Cerro Gordo, Chickasaw and 13 more | 6 hr |
| Jul 10, 10:27 PM CDT | Mesoscale Discussion | SPC | Cherokee, Harrison, Monona, Plymouth, Sioux, Woodbury | 63 min |
| Jul 10, 11:45 PM CDT | Mesoscale Discussion | SPC | Allamakee, Bremer, Cerro Gordo, Chickasaw, Clayton, Delaware and 8 more | 90 min |
| Jul 10, 11:56 PM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more | 4 hr |
| Jul 11, 1:08 AM CDT | Severe Thunderstorm Watch | SPC | Adair, Adams, Audubon, Black Hawk, Boone, Bremer and 38 more | 13 min |
| Jul 11, 1:21 AM CDT | Severe Thunderstorm Watch | SPC | Adair, Adams, Audubon, Black Hawk, Boone, Bremer and 38 more | 4 hr |
| Jul 11, 2:36 AM CDT | Mesoscale Discussion | SPC | Adair, Adams, Benton, Black Hawk, Boone, Bremer and 52 more | 114 min |
| Jul 11, 3:30 AM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Benton, Buchanan, Cedar, Chickasaw, Clayton and 18 more | 6 hr |
| Jul 11, 5:07 AM CDT | Mesoscale Discussion | SPC | Benton, Black Hawk, Buchanan, Cedar, Clayton, Clinton and 15 more | 113 min |
| Jul 10, 7:21 PM CDT | Mesoscale Discussion | SPC | Adams, Blaine, Brown, Buffalo, Chase, Custer and 29 more | 84 min |
| Jul 10, 7:24 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Blaine, Boyd, Brown, Buffalo, Chase and 38 more | 6 hr |
| Jul 11, 2:50 PM CDT | Mesoscale Discussion | SPC | Arthur, Banner, Box Butte, Cheyenne, Dawes, Deuel and 8 more | 85 min |
| Jul 11, 3:07 PM CDT | Severe Thunderstorm Watch | SPC | Banner, Box Butte, Cheyenne, Dawes, Deuel, Garden and 5 more | 7 hr |
| Jul 11, 5:01 PM CDT | Mesoscale Discussion | SPC | Cherry, Dawes, Sheridan | 29 min |
| Jul 11, 5:06 PM CDT | Tornado Watch | SPC | Box Butte, Cherry, Dawes, Sheridan, Sioux | 5 hr |
Nearby
Severe Thunderstorm Watches in Nebraska, 2011Severe Thunderstorm Watches in Iowa, 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.