Alert archive / Montana / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 237
The Storm Prediction Center issued this severe thunderstorm watch at Jun 4, 2021, 4:01 PM MDT for 19 counties in Montana. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 4, 2021, 4:01 PM MDT (22:01 UTC)
- Expired
- Jun 4, 2021, 11:00 PM MDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
Counties Custer County, MT, Dawson County, MT, Fallon County, MT, Fergus County, MT, Garfield County, MT, Golden Valley County, MT, Judith Basin County, MT, McCone County, MT, Meagher County, MT, Musselshell County, MT, Park County, MT, Petroleum County, MT, Prairie County, MT, Richland County, MT, Rosebud County, MT, Sweet Grass County, MT, Treasure County, MT, Wheatland County, MT, Wibaux County, MT
The radar
The Billings radar (KBLX), 109 km from the middle of the area, began a volume at 22:04 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
- 40%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 70%
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 |
|---|---|---|---|---|
| Jun 4, 4:19 PM MDT | Severe Thunderstorm Warning | TFX | Meagher | 26 min |
| Jun 4, 4:55 PM MDT | Severe Thunderstorm Warning | BYZ | Sweet Grass, Wheatland | 35 min |
| Jun 4, 8:54 PM MDT | Severe Thunderstorm Warning | GGW | Dawson, Garfield, McCone | 66 min |
| Jun 4, 9:34 PM MDT | Severe Thunderstorm Warning | GGW | Dawson, McCone, Richland | 56 min |
| Jun 4, 9:45 PM MDT | Severe Thunderstorm Warning | TFX | Fergus | 45 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
Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 10.0 hours before the alert went out and 197 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
- 59 J/kg
- Mixed-layer CIN
- -404 J/kg
- Mixed-layer LCL
- 2879 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km storm-relative helicity
- 63 m²/s²
- 0-3 km storm-relative helicity
- 70 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
331 WWUS20 KWNS 042158 SEL7 SPC WW 042158 MTZ000-050500- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 237 NWS Storm Prediction Center Norman OK 400 PM MDT Fri Jun 4 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of South central into east central Montana * Effective this Friday afternoon and evening from 400 PM until 1100 PM MDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1 inch in diameter possible SUMMARY...A cluster or two of high-based thunderstorms will spread generally eastward from south central Montana this afternoon into east central Montana through late evening. The storm environment favors a few damaging outflow gusts of 60-70 mph as the primary threat, and isolated large hail near 1 inch in diameter may also occur. The severe thunderstorm watch area is approximately along and 50 statute miles north and south of a line from 45 miles north northwest of Livingston MT to 35 miles east of Glendive MT. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). PRECAUTIONARY/PREPAREDNESS ACTIONS... 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 235...WW 236... AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 26030. ...Thompson
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 4, 1:59 PM MDT | Mesoscale Discussion | SPC | Beaverhead, Broadwater, Deer Lodge, Gallatin, Granite, Jefferson and 7 more | 2 hr |
Nearby
Severe Thunderstorm Watches in Montana, 2021Every severe thunderstorm watch in 2021
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.