Alert archive / Nebraska / Mesoscale Discussions in 2021

Mesoscale Discussion 1299

July 16, 20218 counties in Nebraska; 5 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 16, 2021, 2:16 PM MDT for 8 counties in Nebraska; 5 counties in South Dakota. It was in force for 119 min.

The area

The outline as issued.

The facts

Issued: Jul 16, 2021, 2:16 PM MDT (20:16 UTC)
Expired: Jul 16, 2021, 4:15 PM MDT
In force: 119 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch possible
Chance of a watch: 40%

Counties Arthur County, NE, Box Butte County, NE, Dawes County, NE, Garden County, NE, Grant County, NE, Morrill County, NE, Sheridan County, NE, Sioux County, NE, Bennett County, SD, Custer County, SD, Fall River County, SD, Oglala Lakota County, SD, Pennington County, SD

The radar

The Rapid City radar (KUDX), 136 km from the middle of the area, began a volume at 20:15 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 381Jul 16, 3:50 PM MDT

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 8.3 hours before the alert went out and 130 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: 513 J/kg
Mixed-layer CIN: -245 J/kg
Mixed-layer LCL: 2416 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 0 m²/s²
0-3 km storm-relative helicity: -17 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
Jul 16, 3:55 PM MDT	Severe Thunderstorm Watch	SPC	Arthur, Box Butte, Chase, Cherry, Cheyenne, Dawes and 11 more	7 hr

Nearby

Mesoscale Discussions in Nebraska, 2021 Mesoscale Discussions in South Dakota, 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.