Alert archive / Montana / Severe Thunderstorm Watches in 2026
Severe Thunderstorm Watch 596
The Storm Prediction Center issued this severe thunderstorm watch at Aug 18, 2026, 2:31 PM MDT for 10 counties in Montana; 5 counties in Wyoming. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 18, 2026, 2:31 PM MDT (20:31 UTC)
- Expired
- Aug 18, 2026, 7:35 PM MDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
Counties Big Horn County, MT, Carbon County, MT, Carter County, MT, Custer County, MT, Fallon County, MT, Musselshell County, MT, Powder River County, MT, Rosebud County, MT, Treasure County, MT, Yellowstone County, MT, Big Horn County, WY, Johnson County, WY, Park County, WY, Sheridan County, WY, Washakie County, WY
The radar
The Billings radar (KBLX), 68 km from the middle of the area, began a volume at 20:34 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
- 5%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 20%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 60%
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 18, 3:04 PM MDT | Severe Thunderstorm Warning | BYZ | Custer, Rosebud | 56 min |
| Aug 18, 3:07 PM MDT | Severe Thunderstorm Warning | BYZ | Musselshell, Rosebud | 38 min |
| Aug 18, 3:42 PM MDT | Severe Thunderstorm Warning | BYZ | Rosebud, Treasure | 24 min |
| Aug 18, 3:52 PM MDT | Severe Thunderstorm Warning | BYZ | Custer, Rosebud | 38 min |
| Aug 18, 4:27 PM MDT | Severe Thunderstorm Warning | BYZ | Custer | 21 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 1:51 PM MDT | Mesoscale Discussion | SPC | Big Horn, Carbon, Fergus, Gallatin, Golden Valley, Musselshell and 9 more | 84 min |
Nearby
Severe Thunderstorm Watches in Montana, 2026Severe Thunderstorm Watches in Wyoming, 2026Every severe thunderstorm watch in 2026
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; radar from the NEXRAD Level II archive.