Alert archive / Montana / Mesoscale Discussions in 2021
Mesoscale Discussion 1080
The Storm Prediction Center issued this mesoscale discussion at Jun 24, 2021, 2:37 PM MDT for 11 counties in Montana; Lawrence County, South Dakota; Campbell County, Crook County, Weston County, Wyoming. It was in force for 83 min.
The area
The outline as issued.
The facts
- Issued
- Jun 24, 2021, 2:37 PM MDT (20:37 UTC)
- Expired
- Jun 24, 2021, 4:00 PM MDT
- In force
- 83 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Carter County, MT, Custer County, MT, Dawson County, MT, Fallon County, MT, Garfield County, MT, McCone County, MT, Phillips County, MT, Powder River County, MT, Prairie County, MT, Roosevelt County, MT, Valley County, MT, Lawrence County, SD, Campbell County, WY, Crook County, WY, Weston County, WY
The radar
The Billings radar (KBLX), 173 km from the middle of the area, began a volume at 20:40 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 12:00Z, 8.6 hours before the alert went out and 253 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
- 1796 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- 125 m²/s²
- 0-3 km storm-relative helicity
- 207 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
227
ACUS11 KWNS 242038
SWOMCD
SPC MCD 242037
SDZ000-NDZ000-MTZ000-WYZ000-242200-
Mesoscale Discussion 1080
NWS Storm Prediction Center Norman OK
0337 PM CDT Thu Jun 24 2021
Areas affected...Portions of eastern Montana...northeast
Wyoming...and western South Dakota
Concerning...Severe potential...Watch unlikely
Valid 242037Z - 242200Z
Probability of Watch Issuance...5 percent
SUMMARY...Isolated severe wind gusts are possible through the
evening.
DISCUSSION...Widely scattered storms have formed in portions of
eastern Montana to near the Black Hills and into Wyoming. These
storms have formed in an airmass characterized by MLCAPE around 500
J/kg and effective shear between 30 and 40 knots. This shear has
proven sufficient for a few supercell structures in eastern Montana,
but storm mode has been more messy from northeast Wyoming into the
Black Hills. The limited instability should limit the overall threat
for severe hail, but a well-mixed boundary layer and steep lapse
rates should support a threat for damaging winds with any of this
storm activity. Currently, the strongest storms in eastern Montana
are on the eastern periphery of the hot, well-mixed boundary layer
and may move into a more stable airmass across western North Dakota.
A watch is not anticipated given the isolated threat and the
potential for storms to move east of the better instability in the
next 1 to 2 hours.
..Bentley/Hart.. 06/24/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...BIS...UNR...CYS...BYZ...GGW...RIW...TFX...
LAT...LON 47940897 48990654 48480483 44910355 43930315 43530397
43410558 43380593 43640606 44740612 45840610 46560667
47170816 47310860 47430885 47940897SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 24, 1:11 PM MDT | Mesoscale Discussion | SPC | Cascade, Flathead, Glacier, Lewis and Clark, Pondera, Teton | 2 hr |
| Jun 23, 7:10 PM MDT | Mesoscale Discussion | SPC | Bon Homme, Charles Mix, Clay, Davison, Douglas, Gregory and 5 more | 95 min |
Nearby
Mesoscale Discussions in Montana, 2021Mesoscale Discussions in Wyoming, 2021Mesoscale Discussions in South Dakota, 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.