Alert archive / Montana / Mesoscale Discussions in 2016

Mesoscale Discussion 669

May 21, 20169 counties in Montana; Sheridan County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at May 21, 2016, 4:37 PM MDT for 9 counties in Montana; Sheridan County, Wyoming. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued: May 21, 2016, 4:37 PM MDT (22:37 UTC)
Expired: May 21, 2016, 5:30 PM MDT
In force: 53 min
Issued by: the Storm Prediction Center

Counties Big Horn County, MT, Garfield County, MT, Musselshell County, MT, Petroleum County, MT, Phillips County, MT, Rosebud County, MT, Treasure County, MT, Valley County, MT, Yellowstone County, MT, Sheridan County, WY

The radar

The Glasgow radar (KGGW), 146 km from the middle of the area, began a volume at 22:38 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 12:00Z, 10.6 hours before the alert went out and 148 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: 1132 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 98 m²/s²
0-3 km storm-relative helicity: 48 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 21, 2:10 PM MDT	Mesoscale Discussion	SPC	Blaine, Carbon, Fergus, Golden Valley, Musselshell, Petroleum and 2 more	65 min
May 21, 2:26 PM MDT	Severe Thunderstorm Watch	SPC	Big Horn, Daniels, Dawson, Fergus, Garfield, Golden Valley and 13 more	7 hr
May 21, 2:54 PM MDT	Mesoscale Discussion	SPC	Carter, Custer, Dawson, Fallon, Powder River, Prairie and 2 more	2 hr
May 21, 5:03 PM MDT	Severe Thunderstorm Watch	SPC	Carter, Custer, Fallon, Powder River	5 hr

Nearby

Mesoscale Discussions in Montana, 2016 Mesoscale Discussions in Wyoming, 2016 Every mesoscale discussion in 2016

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.