Alert archive / Montana / Severe Thunderstorm Watches in 2006
Severe Thunderstorm Watch 367
The Storm Prediction Center issued this severe thunderstorm watch at May 20, 2006, 12:24 PM MDT for 22 counties in Montana. It was in force for 8 hr.
The area
The outline as issued.
The facts
- Issued
- May 20, 2006, 12:24 PM MDT (18:24 UTC)
- Expired
- May 20, 2006, 8:00 PM MDT
- In force
- 8 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 22 counties
Big Horn County, MT, Broadwater County, MT, Carbon County, MT, Cascade County, MT, Chouteau County, MT, Fergus County, MT, Gallatin County, MT, Golden Valley County, MT, Jefferson County, MT, Judith Basin County, MT, Lewis and Clark County, MT, Madison County, MT, Meagher County, MT, Musselshell County, MT, Park County, MT, Rosebud County, MT, Stillwater County, MT, Sweet Grass County, MT, Teton County, MT, Treasure County, MT, Wheatland County, MT, Yellowstone County, MT
The radar
The Billings radar (KBLX), 138 km from the middle of the area, began a volume at 18:24 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
- 10%
- 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
5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 20, 2:41 PM MDT | Severe Thunderstorm Warning | TFX | Chouteau | 64 min |
| May 20, 3:15 PM MDT | Severe Thunderstorm Warning | BYZ | Rosebud | 30 min |
| May 20, 3:45 PM MDT | Severe Thunderstorm Warning | TFX | Chouteau | 35 min |
| May 20, 4:23 PM MDT | Severe Thunderstorm Warning | TFX | Fergus | 67 min |
| May 20, 5:18 PM MDT | Severe Thunderstorm Warning | BYZ | Stillwater | 42 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
Great_falls, MT (KTFX), launched 12:00Z, 6.4 hours before the alert went out and 109 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
- 2032 m above ground
- 0-6 km bulk shear
- 17 kt
- 0-1 km storm-relative helicity
- -25 m²/s²
- 0-3 km storm-relative helicity
- 72 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 19, 6:47 PM MDT | Mesoscale Discussion | SPC | Mineral, Sanders | 88 min |
| May 20, 11:42 AM MDT | Mesoscale Discussion | SPC | Big Horn, Broadwater, Carbon, Cascade, Chouteau, Fergus and 16 more | 2 hr |
| May 20, 2:53 PM MDT | Mesoscale Discussion | SPC | Big Horn, Broadwater, Carbon, Cascade, Fergus, Gallatin and 13 more | 2 hr |
Nearby
Severe Thunderstorm Watches in Montana, 2006Every severe thunderstorm watch in 2006
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.