Alert archive / Nebraska / Mesoscale Discussions in 2021

Mesoscale Discussion 1974

December 9, 20218 counties in Nebraska; 4 counties in South Dakota; Goshen County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Dec 9, 2021, 8:49 PM MST for 8 counties in Nebraska; 4 counties in South Dakota; Goshen County, Wyoming. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Dec 9, 2021, 8:49 PM MST (03:49 UTC)
Expired: Dec 10, 2021, 1:45 AM MST
In force: 5 hr
Issued by: the Storm Prediction Center
Concerning: Heavy snow

Counties Box Butte County, NE, Brown County, NE, Cherry County, NE, Dawes County, NE, Keya Paha County, NE, Rock County, NE, Sheridan County, NE, Sioux County, NE, Bennett County, SD, Fall River County, SD, Gregory County, SD, Todd County, SD, Goshen County, WY

The radar

The North Platte radar (KLNX), 146 km from the middle of the area, began a volume at 03:52 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

Rapid City, SD (KUNR), launched 00:00Z, 3.8 hours before the alert went out and 189 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: 799 m above ground
0-6 km bulk shear: 74 kt
0-1 km storm-relative helicity: 34 m²/s²
0-3 km storm-relative helicity: 1 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
Dec 10, 8:10 AM MST	Mesoscale Discussion	SPC	Boyd, Keya Paha	4 hr
Dec 10, 1:39 AM MST	Mesoscale Discussion	SPC	Bennett, Custer, Fall River, Jackson, Mellette, Oglala Lakota and 2 more	4 hr
Dec 10, 11:27 AM MST	Mesoscale Discussion	SPC	Bon Homme, Clay, Hanson, Hutchinson, Lake, Lincoln and 6 more	4 hr

Nearby

Mesoscale Discussions in Nebraska, 2021 Mesoscale Discussions in South Dakota, 2021 Mesoscale Discussions in Wyoming, 2021 Every mesoscale discussion in 2021

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.