Alert archive / Nebraska / Severe Thunderstorm Watches in 2007
Severe Thunderstorm Watch 577
The Storm Prediction Center issued this severe thunderstorm watch at Aug 9, 2007, 8:18 PM CDT for 7 counties in Nebraska; Bon Homme County, Yankton County, South Dakota. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 9, 2007, 8:18 PM CDT (01:18 UTC)
- Expired
- Aug 10, 2007, 12:00 AM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
Counties Antelope County, NE, Cedar County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Stanton County, NE, Wayne County, NE, Bon Homme County, SD, Yankton County, SD
The radar
The Sioux Falls radar (KFSD), 133 km from the middle of the area, began a volume at 01:18 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
- 40%
- 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
- 80%
Warnings issued inside it
9 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 9, 8:23 PM CDT | Severe Thunderstorm Warning | OAX | Antelope, Knox | 52 min |
| Aug 9, 9:15 PM CDT | Severe Thunderstorm Warning | OAX | Antelope, Boone | 30 min |
| Aug 9, 9:28 PM CDT | Severe Thunderstorm Warning | FSD | Hutchinson, Yankton | 47 min |
| Aug 9, 9:37 PM CDT | Severe Thunderstorm Warning | OAX | Madison, Pierce | 23 min |
| Aug 9, 9:44 PM CDT | Severe Thunderstorm Warning | OAX | Antelope, Boone | 31 min |
| Aug 9, 9:51 PM CDT | Severe Thunderstorm Warning | OAX | Cedar, Knox | 39 min |
| Aug 9, 10:00 PM CDT | Severe Thunderstorm Warning | OAX | Madison, Pierce | 30 min |
| Aug 9, 10:29 PM CDT | Severe Thunderstorm Warning | OAX | Madison, Stanton | 46 min |
| Aug 9, 10:37 PM CDT | Severe Thunderstorm Warning | OAX | Wayne | 23 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, 1.3 hours before the alert went out and 190 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
- 3891 J/kg
- Mixed-layer CIN
- -7 J/kg
- Mixed-layer LCL
- 1233 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 72 m²/s²
- 0-3 km storm-relative helicity
- 236 m²/s²
- Significant tornado parameter
- 1.4
- Supercell composite
- 13.9
The text
As transmitted, in the capitals the NWS used until 2016.
000
WWUS20 KWNS 100116
SEL7
SPC WW 100116
NEZ000-SDZ000-100500-
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 577
NWS STORM PREDICTION CENTER NORMAN OK
820 PM CDT THU AUG 9 2007
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
NORTHEAST NEBRASKA
SOUTHEAST SOUTH DAKOTA
EFFECTIVE THIS THURSDAY NIGHT FROM 820 PM UNTIL MIDNIGHT CDT.
HAIL TO 2 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 50
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 55 MILES WEST
SOUTHWEST OF YANKTON SOUTH DAKOTA TO 40 MILES NORTHEAST OF
NORFOLK NEBRASKA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).
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 576...
DISCUSSION...BOW ECHO IS ORGANIZING OVER NORTHEAST NEB IN REGION OF
EXTREME INSTABILITY AND FAVORABLE DEEP LAYER VERTICAL SHEAR. THIS
COMPLEX OF STORMS MAY POSE A CONTINUED RISK OF DAMAGING WINDS FOR
ANOTHER 2-3 HOURS AS IT TRACKS EASTWARD ACROSS WATCH AREA.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 27030.
...HARTSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 9, 9:33 PM CDT | Mesoscale Discussion | SPC | Antelope, Boone, Boyd, Burt, Butler, Cedar and 18 more | 87 min |
| Aug 9, 10:14 PM CDT | Severe Thunderstorm Watch | SPC | Antelope, Boone, Burt, Butler, Cass, Cedar and 18 more | 6 hr |
| Aug 10, 1:45 AM CDT | Mesoscale Discussion | SPC | Antelope, Boone, Boyd, Burt, Butler, Cass and 23 more | 60 min |
| Aug 10, 4:25 AM CDT | Mesoscale Discussion | SPC | Antelope, Boyd, Cedar, Colfax, Cuming, Dixon and 8 more | 35 min |
| Aug 10, 10:45 AM CDT | Mesoscale Discussion | SPC | Boyd, Brown, Cherry, Grant, Keya Paha, Rock | 90 min |
| Aug 10, 12:28 PM CDT | Severe Thunderstorm Watch | SPC | Antelope, Cedar, Dakota, Dixon, Knox, Pierce and 2 more | 5 hr |
| Aug 10, 4:33 PM CDT | Mesoscale Discussion | SPC | Blaine, Brown, Cherry, Hooker, Thomas | 57 min |
| Aug 10, 5:03 PM CDT | Severe Thunderstorm Watch | SPC | Arthur, Blaine, Brown, Cherry, Custer, Garden and 9 more | 6 hr |
| Aug 10, 2:04 PM CDT | Mesoscale Discussion | SPC | Campbell, Corson, Dewey, Edmunds, McPherson, Potter and 4 more | 116 min |
| Aug 10, 3:41 PM CDT | Severe Thunderstorm Watch | SPC | Brown, Campbell, Corson, Dewey, Edmunds, Faulk and 4 more | 8 hr |
Nearby
Severe Thunderstorm Watches in Nebraska, 2007Severe Thunderstorm Watches in South Dakota, 2007Every severe thunderstorm watch in 2007
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.