Alert archive / Wyoming / Severe Thunderstorm Watches in 2018
Severe Thunderstorm Watch 83
The Storm Prediction Center issued this severe thunderstorm watch at May 11, 2018, 2:02 PM MDT for Larimer County, Weld County, Colorado; 4 counties in Nebraska; 7 counties in Wyoming. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- May 11, 2018, 2:02 PM MDT (20:02 UTC)
- Expired
- May 11, 2018, 8:49 PM MDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 60 kt
Counties Larimer County, CO, Weld County, CO, Banner County, NE, Kimball County, NE, Scotts Bluff County, NE, Sioux County, NE, Albany County, WY, Carbon County, WY, Converse County, WY, Goshen County, WY, Laramie County, WY, Niobrara County, WY, Platte County, WY
The radar
The Cheyenne radar (KCYS), 51 km from the middle of the area, began a volume at 20:03 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
- 20%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 50%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
10 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 2:11 PM MDT | Severe Thunderstorm Warning | CYS | Albany, Platte | 37 min |
| May 11, 2:38 PM MDT | Severe Thunderstorm Warning | CYS | Goshen, Platte | 36 min |
| May 11, 3:36 PM MDT | Severe Thunderstorm Warning | CYS | Laramie, Platte | 24 min |
| May 11, 4:33 PM MDT | Severe Thunderstorm Warning | CYS | Laramie, Platte | 24 min |
| May 11, 4:34 PM MDT | Severe Thunderstorm Warning | CYS | Goshen, Laramie | 26 min |
| May 11, 4:49 PM MDT | Severe Thunderstorm Warning | CYS | Carbon | 41 min |
| May 11, 5:27 PM MDT | Severe Thunderstorm Warning | CYS | Carbon | 33 min |
| May 11, 5:59 PM MDT | Severe Thunderstorm Warning | CYS | Carbon | 46 min |
| May 11, 6:10 PM MDT | Severe Thunderstorm Warning | CYS | Carbon | 26 min |
| May 11, 6:39 PM MDT | Severe Thunderstorm Warning | CYS | Carbon | 51 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 (KDEN), launched 12:00Z, 8.0 hours before the alert went out and 245 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
- 1147 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- -91 m²/s²
- 0-3 km storm-relative helicity
- 66 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 |
|---|---|---|---|---|
| May 10, 6:06 PM MDT | Mesoscale Discussion | SPC | Cheyenne, Kit Carson, Lincoln, Washington, Yuma | 114 min |
| May 10, 6:59 PM MDT | Severe Thunderstorm Watch | SPC | Yuma | 9 hr |
| May 11, 12:00 PM MDT | Mesoscale Discussion | SPC | Boulder, Broomfield, Larimer, Weld | 2 hr |
| May 11, 5:39 PM MDT | Mesoscale Discussion | SPC | Larimer, Weld | 96 min |
| May 10, 6:39 PM MDT | Mesoscale Discussion | SPC | Adams, Arthur, Blaine, Buffalo, Chase, Custer and 25 more | 2 hr |
| May 10, 10:16 PM MDT | Mesoscale Discussion | SPC | Adams, Antelope, Boone, Buffalo, Chase, Custer and 19 more | 89 min |
| May 11, 12:13 AM MDT | Mesoscale Discussion | SPC | Butler, Cass, Douglas, Gage, Jefferson, Johnson and 7 more | 92 min |
| May 11, 12:50 AM MDT | Severe Thunderstorm Watch | SPC | Butler, Cass, Gage, Jefferson, Johnson, Lancaster and 6 more | 3 hr |
| May 11, 3:24 AM MDT | Mesoscale Discussion | SPC | Adams, Butler, Cass, Clay, Colfax, Douglas and 22 more | 66 min |
Nearby
Severe Thunderstorm Watches in Wyoming, 2018Severe Thunderstorm Watches in Nebraska, 2018Severe Thunderstorm Watches in Colorado, 2018Every severe thunderstorm watch in 2018
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.