Alert archive / Montana / Mesoscale Discussions in 2011

Mesoscale Discussion 1618

July 14, 201117 counties in Montana; Sheridan County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Jul 14, 2011, 6:33 PM MDT for 17 counties in Montana; Sheridan County, Wyoming. It was in force for 57 min.

The area

The outline as issued.

The facts

Issued: Jul 14, 2011, 6:33 PM MDT (00:33 UTC)
Expired: Jul 14, 2011, 7:30 PM MDT
In force: 57 min
Issued by: the Storm Prediction Center

Counties Big Horn County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Garfield County, MT, McCone County, MT, Musselshell County, MT, Petroleum County, MT, Phillips County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Rosebud County, MT, Sheridan County, MT, Treasure County, MT, Valley County, MT, Yellowstone County, MT, Sheridan County, WY

The radar

The Billings radar (KBLX), 155 km from the middle of the area, began a volume at 00:36 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 645Jul 14, 10:00 PM MDT

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 0.6 hours before the alert went out and 229 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: 272 J/kg
Mixed-layer CIN: -124 J/kg
Mixed-layer LCL: 2109 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: -22 m²/s²
0-3 km storm-relative helicity: 106 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.9

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
Jul 14, 10:01 PM MDT	Severe Thunderstorm Watch	SPC	Carter, Custer, Fallon, Powder River	6 hr
Jul 15, 1:54 AM MDT	Mesoscale Discussion	SPC	Carter, Dawson, Fallon, Powder River, Richland, Wibaux	2 hr
Jul 15, 2:39 PM MDT	Mesoscale Discussion	SPC	Big Horn, Broadwater, Carbon, Custer, Gallatin, Golden Valley and 13 more	2 hr
Jul 15, 3:26 PM MDT	Severe Thunderstorm Watch	SPC	Big Horn, Carbon, Custer, Golden Valley, Musselshell, Powder River and 4 more	6 hr
Jul 14, 8:05 PM MDT	Mesoscale Discussion	SPC	Laramie	55 min

Nearby

Mesoscale Discussions in Montana, 2011 Mesoscale Discussions in Wyoming, 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.