Alert archive / South Dakota / Mesoscale Discussions in 2014

Mesoscale Discussion 1632

August 28, 2014Lyon County, Sioux County, Iowa; Knox County, Nebraska; 5 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 28, 2014, 7:49 PM CDT for Lyon County, Sioux County, Iowa; Knox County, Nebraska; 5 counties in South Dakota. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued
Aug 28, 2014, 7:49 PM CDT (00:49 UTC)
Expired
Aug 28, 2014, 9:15 PM CDT
In force
86 min
Issued by
the Storm Prediction Center
Chance of a watch
5%

Counties Lyon County, IA, Sioux County, IA, Knox County, NE, Bon Homme County, SD, Clay County, SD, Lincoln County, SD, Turner County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 101 km from the middle of the area, began a volume at 00:49 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

Omaha, NE (KOAX), launched 00:00Z, 0.8 hours before the alert went out and 198 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-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2014-08-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 581 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 00:00Z on 2014-08-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 87 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
581 J/kg
Mixed-layer CIN
-84 J/kg
Mixed-layer LCL
1173 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
87 m²/s²
0-3 km storm-relative helicity
69 m²/s²
Significant tornado parameter
0.1
Supercell composite
4.4

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.

IssuedProductOfficeCountiesLasted
Aug 29, 1:33 PM CDTMesoscale DiscussionSPCFremont, Mills, Montgomery, Page, Taylor2 hr
Aug 29, 3:02 PM CDTMesoscale DiscussionSPCBenton, Black Hawk, Bremer, Buchanan, Butler, Cedar and 29 more2 hr

Nearby

Mesoscale Discussions in South Dakota, 2014Mesoscale Discussions in Iowa, 2014Mesoscale Discussions in Nebraska, 2014Every mesoscale discussion in 2014

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.