Alert archive / Montana / Mesoscale Discussions in 2021
Mesoscale Discussion 853
The Storm Prediction Center issued this mesoscale discussion at Jun 4, 2021, 8:10 PM MDT for 14 counties in Montana. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 4, 2021, 8:10 PM MDT (02:10 UTC)
- Expired
- Jun 4, 2021, 10:15 PM MDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 237
Counties Custer County, MT, Dawson County, MT, Garfield County, MT, Golden Valley County, MT, Judith Basin County, MT, Musselshell County, MT, Petroleum County, MT, Prairie County, MT, Rosebud County, MT, Sweet Grass County, MT, Treasure County, MT, Wheatland County, MT, Wibaux County, MT, Yellowstone County, MT
The radar
The Billings radar (KBLX), 169 km from the middle of the area, began a volume at 02:11 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, 2.2 hours before the alert went out and 176 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
- 291 J/kg
- Mixed-layer CIN
- -22 J/kg
- Mixed-layer LCL
- 3180 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- -11 m²/s²
- 0-3 km storm-relative helicity
- 90 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.2
The text
As transmitted.
181 ACUS11 KWNS 050211 SWOMCD SPC MCD 050210 NDZ000-MTZ000-050415- Mesoscale Discussion 0853 NWS Storm Prediction Center Norman OK 0910 PM CDT Fri Jun 04 2021 Areas affected...eastern Montana Concerning...Severe Thunderstorm Watch 237... Valid 050210Z - 050415Z The severe weather threat for Severe Thunderstorm Watch 237 continues. SUMMARY...The threat for sporadic severe gusts and marginal hail continues over parts of eastern Montana this evening. DISCUSSION...Several left-moving cells are currently moving east/northeast along the northern fringe of WW 237, and may produce marginal hail as well as strong wind gusts. The 00Z soundings from TFX and GGW show mainly unidirectional flow aloft, with up to 50 kt just below 500 mb. The GGW sounding in particular shows a good hodograph for splitting cells. Deep mixed layers are also noted due to warm surface temperatures, with little CIN currently. Therefore, while convection remains sparse across parts of the watch, additional activity may yet develop over the next 1-2 hours along various outflows, with both wind and marginal hail threat. ..Jewell.. 06/05/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BIS...BYZ...GGW...TFX... LAT...LON 46390401 45581078 47011078 47840402 46390401
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 5, 2:27 PM MDT | Mesoscale Discussion | SPC | Carbon, Gallatin, Golden Valley, Musselshell, Park, Stillwater and 4 more | 2 hr |
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.