Alert archive / North Dakota / Mesoscale Discussions in 2021

Mesoscale Discussion 1202

July 8, 20219 counties in Montana; 11 counties in North Dakota; Butte County, Harding County, Perkins County, South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 8, 2021, 2:34 PM MDT for 9 counties in Montana; 11 counties in North Dakota; Butte County, Harding County, Perkins County, South Dakota. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Jul 8, 2021, 2:34 PM MDT (20:34 UTC)
Expired: Jul 8, 2021, 4:00 PM MDT
In force: 86 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 352

All 23 counties

Daniels County, MT, Dawson County, MT, Fallon County, MT, McCone County, MT, Richland County, MT, Roosevelt County, MT, Sheridan County, MT, Valley County, MT, Wibaux County, MT, Adams County, ND, Billings County, ND, Bowman County, ND, Divide County, ND, Dunn County, ND, Golden Valley County, ND, Hettinger County, ND, McKenzie County, ND, Slope County, ND, Stark County, ND, Williams County, ND, Butte County, SD, Harding County, SD, Perkins County, SD

The radar

The Glasgow radar (KGGW), 205 km from the middle of the area, began a volume at 20:35 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

Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 8.6 hours before the alert went out and 204 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 102 J/kg
Mixed-layer CIN: -411 J/kg
Mixed-layer LCL: 1738 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 154 m²/s²
0-3 km storm-relative helicity: 162 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

004 
ACUS11 KWNS 082034
SWOMCD
SPC MCD 082034 
SDZ000-NDZ000-MTZ000-WYZ000-082200-

Mesoscale Discussion 1202
NWS Storm Prediction Center Norman OK
0334 PM CDT Thu Jul 08 2021

Areas affected...western North Dakota into portions of South Dakota
and Montana.

Concerning...Severe Thunderstorm Watch 352...

Valid 082034Z - 082200Z

The severe weather threat for Severe Thunderstorm Watch 352
continues.

SUMMARY...Ahead of ongoing severe storms across WW 352, a
destabilizing airmass will support additional thunderstorm
development this afternoon and evening. A downstream watch will
likely be needed by 21-22z.

DISCUSSION...Several supercells ongoing in northeastern Montana
should continue into a destabilizing airmass across the western
Dakotas over the next hour. While some inhibition remains across
western North Dakota, continuing erosion of residual capping should
allow for additional connective development this afternoon. Some
initial weakening of ongoing storms is expected given remaining
MLCINH, but this should be relatively short lived as robust heating
continues to destabilize the environment. Strong deep-layer shear of
45-55 kts of 1500-2000 K/kg of MLCAPE will support supercells
capable of damaging wind gusts and large to very large hail. Some
upscale growth is also expected later this evening with the
potential for a swath of damaging winds, some of which may be
significant. An additional weather watch is likely needed by 21-22z
for a downstream severe threat across portions of the western
Dakotas.

..Lyons.. 07/08/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...ABR...BIS...UNR...BYZ...GGW...

LAT...LON   46790177 46010173 45280229 44870297 44720370 44990406
            45400434 46380490 47430589 48220685 48440752 48800751
            49050729 49060612 49040572 49040563 49090376 48580312
            48030260 47390208 47000185 46790177

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 8, 1:15 PM MDT	Mesoscale Discussion	SPC	Daniels, Dawson, McCone, Phillips, Prairie, Richland and 2 more	60 min
Jul 8, 5:32 PM MDT	Severe Thunderstorm Watch	SPC	Dawson, Prairie, Richland, Roosevelt, Wibaux	47 min
Jul 8, 3:38 PM MDT	Severe Thunderstorm Watch	SPC	Adams, Billings, Bowman, Burke, Divide, Dunn and 15 more	6 hr
Jul 8, 4:56 PM MDT	Mesoscale Discussion	SPC	Adams, Billings, Bowman, Burke, Divide, Dunn and 10 more	2 hr
Jul 7, 7:15 PM MDT	Mesoscale Discussion	SPC	Custer, Fall River, Lawrence	2 hr
Jul 8, 3:49 PM MDT	Severe Thunderstorm Watch	SPC	Bennett, Butte, Custer, Haakon, Harding, Jackson and 6 more	6 hr

Nearby

Mesoscale Discussions in North Dakota, 2021 Mesoscale Discussions in Montana, 2021 Mesoscale Discussions in South Dakota, 2021 Every 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.