Alert archive / Montana / Mesoscale Discussions in 2021
Mesoscale Discussion 905
The Storm Prediction Center issued this mesoscale discussion at Jun 9, 2021, 10:51 PM MDT for 4 counties in Montana. It was in force for 84 min.
The area
The outline as issued.
The facts
- Issued
- Jun 9, 2021, 10:51 PM MDT (04:51 UTC)
- Expired
- Jun 10, 2021, 12:15 AM MDT
- In force
- 84 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 250
Counties Blaine County, MT, Fergus County, MT, Petroleum County, MT, Phillips County, MT
The radar
The Glasgow radar (KGGW), 143 km from the middle of the area, began a volume at 04:55 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
Great_falls, MT (KTFX), launched 00:00Z, 4.9 hours before the alert went out and 166 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
- 22 J/kg
- Mixed-layer CIN
- -195 J/kg
- Mixed-layer LCL
- 1287 m above ground
- 0-6 km bulk shear
- 71 kt
- 0-1 km storm-relative helicity
- 12 m²/s²
- 0-3 km storm-relative helicity
- 408 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.1
The text
As transmitted.
831
ACUS11 KWNS 100451
SWOMCD
SPC MCD 100451
MTZ000-100615-
Mesoscale Discussion 0905
NWS Storm Prediction Center Norman OK
1151 PM CDT Wed Jun 09 2021
Areas affected...North-central MT
Concerning...Severe Thunderstorm Watch 250...
Valid 100451Z - 100615Z
The severe weather threat for Severe Thunderstorm Watch 250
continues.
SUMMARY...Ongoing storms may pose a threat of hail and wind until
around 06Z, before a decrease in coverage and intensity occurs
overnight.
DISCUSSION...At 0445Z, a supercell is ongoing across southern
Phillips County MT, with other strong storms to the northwest over
Blaine County. As with the previous supercell, the Phillips County
storm may tend to weaken as it moves northeastward into a strongly
capped environment, but some threat may spread out of WW 250 into
Valley County in the short term. Until any weakening occurs,
moderate buoyancy and effective shear of 40-50 kt will continue to
support a threat of large hail. Other storms may briefly attain
severe intensity across Blaine County and northern Phillips County
until around 06Z, but intensity and coverage are expected to
decrease overnight, due to increasing CINH and the effects of
convective overturning across the region. At this time, it does not
appear as if new watch issuance will be needed after WW 250 expires
at 06Z.
..Dean.. 06/10/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GGW...TFX...
LAT...LON 46890981 48480956 49010926 49160836 49080780 48720734
48140718 47470738 47080819 46940905 46890981SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 9, 6:42 PM MDT | Severe Thunderstorm Watch | SPC | Blaine, Chouteau, Fergus, Hill, Judith Basin, Petroleum and 1 more | 5 hr |
| Jun 9, 8:34 PM MDT | Mesoscale Discussion | SPC | Blaine, Chouteau, Fergus, Hill, Judith Basin, Petroleum and 1 more | 86 min |
| Jun 10, 1:47 PM MDT | Mesoscale Discussion | SPC | Blaine, Fergus, Golden Valley, Musselshell, Petroleum, Phillips and 4 more | 88 min |
| Jun 10, 1:56 PM MDT | Mesoscale Discussion | SPC | Daniels, Richland, Roosevelt, Sheridan, Valley, Wibaux | 94 min |
| Jun 10, 2:30 PM MDT | Tornado Watch | SPC | Daniels, Richland, Roosevelt, Sheridan, Wibaux | 6 hr |
| Jun 10, 2:51 PM MDT | Mesoscale Discussion | SPC | Carter | 114 min |
| Jun 10, 2:52 PM MDT | Severe Thunderstorm Watch | SPC | Blaine, Custer, Dawson, Fergus, Garfield, Golden Valley and 7 more | 6 hr |
| Jun 10, 4:36 PM MDT | Mesoscale Discussion | SPC | Fallon, Richland, Roosevelt, Sheridan, Wibaux | 114 min |
| Jun 10, 4:48 PM MDT | Mesoscale Discussion | SPC | Garfield, Golden Valley, Musselshell, Petroleum, Phillips, Treasure and 2 more | 87 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.