Alert archive / Nebraska / Mesoscale Discussions in 2015

Mesoscale Discussion 1673

August 13, 201513 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Aug 13, 2015, 2:45 PM CDT for 13 counties in Nebraska. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Aug 13, 2015, 2:45 PM CDT (19:45 UTC)
Expired: Aug 13, 2015, 4:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Blaine County, NE, Brown County, NE, Chase County, NE, Dundy County, NE, Hayes County, NE, Hitchcock County, NE, Hooker County, NE, Keith County, NE, Lincoln County, NE, Logan County, NE, McPherson County, NE, Perkins County, NE, Thomas County, NE

The radar

The North Platte radar (KLNX), 64 km from the middle of the area, began a volume at 19:42 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 487Aug 13, 5:40 PM CDT

The nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 7.8 hours before the alert went out and 45 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: 522 J/kg
Mixed-layer CIN: -228 J/kg
Mixed-layer LCL: 966 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 14 m²/s²
0-3 km storm-relative helicity: 52 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
Aug 13, 5:42 PM CDT	Severe Thunderstorm Watch	SPC	Blaine, Brown, Cherry, Custer, Dawson, Frontier and 9 more	5 hr
Aug 13, 6:01 PM CDT	Mesoscale Discussion	SPC	Blaine, Brown, Cherry, Custer, Dawson, Hooker and 6 more	29 min

Nearby

Mesoscale Discussions in Nebraska, 2015 Every mesoscale discussion in 2015

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.