Alert archive / Montana / Mesoscale Discussions in 2007
Mesoscale Discussion 841
The Storm Prediction Center issued this mesoscale discussion at May 20, 2007, 1:45 PM MDT for 13 counties in Montana; 4 counties in South Dakota; 6 counties in Wyoming. It was in force for 60 min.
The area
The outline as issued.
The facts
- Issued
- May 20, 2007, 1:45 PM MDT (19:45 UTC)
- Expired
- May 20, 2007, 2:45 PM MDT
- In force
- 60 min
- Issued by
- the Storm Prediction Center
All 23 counties
Big Horn County, MT, Carbon County, MT, Carter County, MT, Custer County, MT, Golden Valley County, MT, Musselshell County, MT, Powder River County, MT, Rosebud County, MT, Stillwater County, MT, Sweet Grass County, MT, Treasure County, MT, Wheatland County, MT, Yellowstone County, MT, Butte County, SD, Harding County, SD, Lawrence County, SD, Meade County, SD, Big Horn County, WY, Campbell County, WY, Crook County, WY, Johnson County, WY, Sheridan County, WY, Weston County, WY
The radar
The Billings radar (KBLX), 136 km from the middle of the area, began a volume at 19:49 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.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Rapid City, SD (KUNR), launched 12:00Z, 7.8 hours before the alert went out and 356 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
- 101 J/kg
- Mixed-layer CIN
- -403 J/kg
- Mixed-layer LCL
- 1152 m above ground
- 0-6 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 107 m²/s²
- 0-3 km storm-relative helicity
- 124 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 19, 9:04 PM MDT | Mesoscale Discussion | SPC | Carter, Custer, Fergus, Garfield, Musselshell, Petroleum and 4 more | 56 min |
| May 20, 2:33 PM MDT | Severe Thunderstorm Watch | SPC | Big Horn, Carbon, Carter, Custer, Dawson, Fallon and 13 more | 9 hr |
| May 20, 5:17 PM MDT | Mesoscale Discussion | SPC | Brule, Buffalo, Hughes, Jones, Lyman, Mellette and 1 more | 88 min |
Nearby
Mesoscale Discussions in Montana, 2007Mesoscale Discussions in Wyoming, 2007Mesoscale Discussions in South Dakota, 2007Every mesoscale discussion in 2007
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.