Alert archive / Montana / Mesoscale Discussions in 2011

Mesoscale Discussion 1445

June 29, 201122 counties in Montana

The Storm Prediction Center issued this mesoscale discussion at Jun 29, 2011, 6:17 PM MDT for 22 counties in Montana. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued: Jun 29, 2011, 6:17 PM MDT (00:17 UTC)
Expired: Jun 29, 2011, 8:15 PM MDT
In force: 118 min
Issued by: the Storm Prediction Center

All 22 counties

Blaine County, MT, Chouteau County, MT, Daniels County, MT, Dawson County, MT, Fergus County, MT, Garfield County, MT, Golden Valley County, MT, Hill County, MT, Judith Basin County, MT, Liberty County, MT, McCone County, MT, Meagher County, MT, Musselshell County, MT, Petroleum County, MT, Phillips County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Sheridan County, MT, Treasure County, MT, Valley County, MT, Wheatland County, MT

The radar

The Billings radar (KBLX), 140 km from the middle of the area, began a volume at 00:20 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.

Tornado Watch 575Jun 29, 7:05 PM MDT

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 0.3 hours before the alert went out and 177 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: 2773 J/kg
Mixed-layer CIN: -109 J/kg
Mixed-layer LCL: 2014 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 15 m²/s²
0-3 km storm-relative helicity: 113 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 4.3

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
Jun 29, 7:03 PM MDT	Tornado Watch	SPC	Daniels, Roosevelt, Sheridan, Valley	4 hr
Jun 29, 9:03 PM MDT	Mesoscale Discussion	SPC	Daniels, Sheridan, Valley	57 min

Nearby

Mesoscale Discussions in Montana, 2011 Every mesoscale discussion in 2011

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.