Alert archive / Nebraska / Tornado Watches in 2009
Tornado Watch 669
The Storm Prediction Center issued this tornado watch at Aug 6, 2009, 4:07 PM MDT for 16 counties in Nebraska; 10 counties in South Dakota. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 6, 2009, 4:07 PM MDT (22:07 UTC)
- Expired
- Aug 6, 2009, 8:20 PM MDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 26 counties
Arthur County, NE, Banner County, NE, Box Butte County, NE, Cherry County, NE, Cheyenne County, NE, Dawes County, NE, Deuel County, NE, Garden County, NE, Grant County, NE, Hooker County, NE, Keith County, NE, Kimball County, NE, Morrill County, NE, Scotts Bluff County, NE, Sheridan County, NE, Sioux County, NE, Bennett County, SD, Custer County, SD, Fall River County, SD, Haakon County, SD, Jackson County, SD, Lawrence County, SD, Meade County, SD, Mellette County, SD, Pennington County, SD, Todd County, SD
The radar
The Rapid City radar (KUDX), 137 km from the middle of the area, began a volume at 22:09 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
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 6, 5:24 PM MDT | Severe Thunderstorm Warning | CYS | Cheyenne | 66 min |
| Aug 6, 6:36 PM MDT | Flash Flood Warning | CYS | Cheyenne | 3 hr |
| Aug 6, 7:14 PM MDT | Severe Thunderstorm Warning | LBF | Garden, Sheridan | 46 min |
| Aug 6, 7:30 PM MDT | Severe Thunderstorm Warning | LBF | Cherry, Sheridan | 45 min |
| Aug 6, 7:37 PM MDT | Severe Thunderstorm Warning | UNR | Bennett | 39 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
Denver, CO (KDNR), launched 12:00Z, 10.1 hours before the alert went out and 337 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2706 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- -1 m²/s²
- 0-3 km storm-relative helicity
- 59 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 |
|---|---|---|---|---|
| Aug 6, 5:28 PM MDT | Mesoscale Discussion | SPC | Dundy | 92 min |
| Aug 5, 8:27 PM MDT | Mesoscale Discussion | SPC | Butte, Haakon, Jackson, Lawrence, Meade, Pennington and 1 more | 93 min |
| Aug 6, 9:38 AM MDT | Mesoscale Discussion | SPC | Brule, Buffalo, Haakon, Jones, Lyman, Mellette and 2 more | 67 min |
| Aug 6, 2:53 PM MDT | Mesoscale Discussion | SPC | Haakon, Jackson, Jones, Meade, Mellette, Pennington and 1 more | 97 min |
Nearby
Tornado Watches in Nebraska, 2009Tornado Watches in South Dakota, 2009Every tornado watch in 2009
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.