Alert archive / Nebraska / Mesoscale Discussions in 2008

Mesoscale Discussion 962

May 21, 20084 states

The Storm Prediction Center issued this mesoscale discussion at May 21, 2008, 2:21 PM MDT for 4 states. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued: May 21, 2008, 2:21 PM MDT (20:21 UTC)
Expired: May 21, 2008, 3:15 PM MDT
In force: 54 min
Issued by: the Storm Prediction Center

Counties Logan County, CO, Weld County, CO, Banner County, NE, Box Butte County, NE, Cheyenne County, NE, Kimball County, NE, Morrill County, NE, Scotts Bluff County, NE, Sioux County, NE, Fall River County, SD, Campbell County, WY, Converse County, WY, Goshen County, WY, Laramie County, WY, Niobrara County, WY, Platte County, WY, Weston County, WY

The radar

The Cheyenne radar (KCYS), 136 km from the middle of the area, began a volume at 20:23 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 333May 21, 2:45 PM MDT

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 8.4 hours before the alert went out and 300 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: 848 J/kg
Mixed-layer CIN: -262 J/kg
Mixed-layer LCL: 1951 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 89 m²/s²
0-3 km storm-relative helicity: 110 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 21, 2:46 PM MDT	Severe Thunderstorm Watch	SPC	Kit Carson, Logan, Morgan, Phillips, Sedgwick, Washington and 2 more	7 hr
May 21, 5:33 PM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Bent, Broomfield, Cheyenne, Crowley and 19 more	57 min

Nearby

Mesoscale Discussions in Nebraska, 2008 Mesoscale Discussions in Wyoming, 2008 Mesoscale Discussions in Colorado, 2008 Every mesoscale discussion in 2008

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.