Alert archive / Montana / Mesoscale Discussions in 2021
Mesoscale Discussion 890
The Storm Prediction Center issued this mesoscale discussion at Jun 8, 2021, 6:15 PM MDT for 14 counties in Montana. It was in force for 90 min.
The area
The outline as issued.
The facts
- Issued
- Jun 8, 2021, 6:15 PM MDT (00:15 UTC)
- Expired
- Jun 8, 2021, 7:45 PM MDT
- In force
- 90 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 247
Counties Carter County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, McCone County, MT, Powder River County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Rosebud County, MT, Sheridan County, MT, Valley County, MT, Wibaux County, MT
The radar
The Glasgow radar (KGGW), 194 km from the middle of the area, began a volume at 00:15 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 nearest sounding before it
Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 0.3 hours before the alert went out and 195 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
- 558 J/kg
- Mixed-layer CIN
- -175 J/kg
- Mixed-layer LCL
- 1718 m above ground
- 0-6 km bulk shear
- 63 kt
- 0-1 km storm-relative helicity
- 279 m²/s²
- 0-3 km storm-relative helicity
- 351 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.9
The text
As transmitted.
967 ACUS11 KWNS 090016 SWOMCD SPC MCD 090015 MTZ000-WYZ000-090145- Mesoscale Discussion 0890 NWS Storm Prediction Center Norman OK 0715 PM CDT Tue Jun 08 2021 Areas affected...Eastern Montana Concerning...Severe Thunderstorm Watch 247... Valid 090015Z - 090145Z The severe weather threat for Severe Thunderstorm Watch 247 continues. SUMMARY...Severe threat will focus across northern and eastern portions of the watch over the next 1-2 hours. DISCUSSION...Notable mid-level short-wave trough has translated across the Great Basin into northwestern WY/south-central MT as evident by an arcing band of weak high-based convection that extends from eastern WY into southern MT. About 150 mi downstream, moist-deep convection is in the process of maturing over northeastern/eastern MT where higher buoyancy and an easterly low-level component persist. Much of this activity, strongly influenced by the approaching short wave, is producing large hail, especially over Richland/Wibaux County MT and northwestern Golden Valley County ND. Additional thunderstorm development will likely intensify across southeast MT as the Dakota outflow boundary propagates into a region of very steep lapse rates where surface temperatures are in the mid-upper 90s. ..Darrow.. 06/09/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BYZ...GGW... LAT...LON 44980672 48960700 48950414 44990405 44980672
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 9, 4:43 PM MDT | Mesoscale Discussion | SPC | Deer Lodge, Granite, Lake, Lewis and Clark, Missoula, Powell and 2 more | 92 min |
| Jun 9, 5:05 PM MDT | Mesoscale Discussion | SPC | Blaine, Cascade, Chouteau, Fergus, Hill, Judith Basin and 2 more | 85 min |
Nearby
Mesoscale Discussions in Montana, 2021Every mesoscale discussion 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.