Alert archive / Wyoming / Severe Thunderstorm Watches in 2010
Severe Thunderstorm Watch 511
The Storm Prediction Center issued this severe thunderstorm watch at Jul 21, 2010, 2:49 PM MDT for Carter County, Powder River County, Montana; 14 counties in Wyoming. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 2010, 2:49 PM MDT (20:49 UTC)
- Expired
- Jul 21, 2010, 10:00 PM MDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
Counties Carter County, MT, Powder River County, MT, Albany County, WY, Campbell County, WY, Carbon County, WY, Converse County, WY, Crook County, WY, Goshen County, WY, Johnson County, WY, Laramie County, WY, Natrona County, WY, Niobrara County, WY, Platte County, WY, Sheridan County, WY, Sweetwater County, WY, Weston County, WY
The radar
The Riverton/Lander radar (KRIW), 93 km from the middle of the area, began a volume at 20:49 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
11 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 3:15 PM MDT | Severe Thunderstorm Warning | BYZ | Sheridan | 30 min |
| Jul 21, 3:27 PM MDT | Severe Thunderstorm Warning | UNR | Campbell | 63 min |
| Jul 21, 3:46 PM MDT | Severe Thunderstorm Warning | RIW | Natrona | 27 min |
| Jul 21, 4:36 PM MDT | Severe Thunderstorm Warning | BYZ | Big Horn, Powder River, Rosebud | 54 min |
| Jul 21, 4:44 PM MDT | Severe Thunderstorm Warning | UNR | Campbell, Crook, Weston | 49 min |
| Jul 21, 5:10 PM MDT | Tornado Warning | UNR | Crook, Weston | 65 min |
| Jul 21, 5:47 PM MDT | Severe Thunderstorm Warning | CYS | Albany | 28 min |
| Jul 21, 6:16 PM MDT | Flash Flood Warning | CYS | Albany | 3 hr |
| Jul 21, 6:28 PM MDT | Severe Thunderstorm Warning | UNR | Weston | 62 min |
| Jul 21, 7:08 PM MDT | Flash Flood Warning | CYS | Niobrara | 2 hr |
| Jul 21, 7:16 PM MDT | Tornado Warning | UNR | Weston | 29 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
Riverton, WY (KRIW), launched 12:00Z, 8.8 hours before the alert went out and 87 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
- 124 J/kg
- Mixed-layer CIN
- -232 J/kg
- Mixed-layer LCL
- 1469 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 12 m²/s²
- 0-3 km storm-relative helicity
- 98 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 1:29 PM MDT | Mesoscale Discussion | SPC | Big Horn, Carter, Custer, Fallon, Powder River, Prairie and 3 more | 2 hr |
| Jul 21, 4:50 PM MDT | Mesoscale Discussion | SPC | Broadwater, Gallatin, Judith Basin, Meagher, Park, Stillwater and 2 more | 55 min |
Nearby
Severe Thunderstorm Watches in Wyoming, 2010Severe Thunderstorm Watches in Montana, 2010Every severe thunderstorm watch in 2010
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.