Alert archive / Montana / Mesoscale Discussions in 2005

Mesoscale Discussion 945

May 20, 200517 counties in Montana; McKenzie County, Williams County, North Dakota

The Storm Prediction Center issued this mesoscale discussion at May 20, 2005, 9:45 PM MDT for 17 counties in Montana; McKenzie County, Williams County, North Dakota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 20, 2005, 9:45 PM MDT (03:45 UTC)
Expired: May 20, 2005, 11:45 PM MDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Big Horn County, MT, Carbon County, MT, Custer County, MT, Dawson County, MT, Golden Valley County, MT, McCone County, MT, Musselshell County, MT, Powder River County, MT, Prairie County, MT, Richland County, MT, Rosebud County, MT, Stillwater County, MT, Sweet Grass County, MT, Treasure County, MT, Wheatland County, MT, Wibaux County, MT, Yellowstone County, MT, McKenzie County, ND, Williams County, ND

The radar

The Glasgow radar (KGGW), 169 km from the middle of the area, began a volume at 03:47 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.

Severe Thunderstorm Watch 308May 20, 10:35 PM MDT

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 3.8 hours before the alert went out and 169 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2659 m above ground
0-6 km bulk shear: 62 kt
0-1 km storm-relative helicity: -35 m²/s²
0-3 km storm-relative helicity: 88 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 20, 6:47 PM MDT	Mesoscale Discussion	SPC	Big Horn, Carbon, Carter, Custer, Dawson, Fallon and 12 more	88 min
May 20, 8:30 PM MDT	Severe Thunderstorm Watch	SPC	Dawson, McCone, Prairie, Richland, Wibaux	5 hr
May 20, 10:35 PM MDT	Severe Thunderstorm Watch	SPC	Big Horn, Carter, Custer, Fallon, Powder River, Rosebud and 1 more	4 hr
May 20, 10:37 PM MDT	Mesoscale Discussion	SPC	Adams, Barnes, Bowman, Burleigh, Cass, Dickey and 20 more	83 min
May 21, 12:08 AM MDT	Mesoscale Discussion	SPC	Adams, Barnes, Bowman, Burleigh, Cass, Dickey and 15 more	97 min
May 21, 12:35 AM MDT	Severe Thunderstorm Watch	SPC	Adams, Barnes, Benson, Billings, Bowman, Burleigh and 29 more	7 hr
May 21, 3:52 AM MDT	Mesoscale Discussion	SPC	Barnes, Benson, Burleigh, Cass, Dickey, Eddy and 22 more	83 min
May 21, 6:43 AM MDT	Mesoscale Discussion	SPC	Barnes, Cass, Eddy, Foster, Grand Forks, Griggs and 7 more	62 min
May 21, 12:24 PM MDT	Mesoscale Discussion	SPC	Cass, Grand Forks, Pembina, Ransom, Richland, Sargent and 3 more	66 min
May 21, 2:50 PM MDT	Mesoscale Discussion	SPC	Bottineau, Cavalier, McHenry, Pierce, Ramsey, Renville and 2 more	115 min

Nearby

Mesoscale Discussions in Montana, 2005 Mesoscale Discussions in North Dakota, 2005 Every mesoscale discussion in 2005

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.