Alert archive / South Dakota / Mesoscale Discussions in 2007

Mesoscale Discussion 524

April 21, 2007Sedgwick County, Colorado; 11 counties in Nebraska; 20 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2007, 12:35 PM MDT for Sedgwick County, Colorado; 11 counties in Nebraska; 20 counties in South Dakota. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued
Apr 21, 2007, 12:35 PM MDT (18:35 UTC)
Expired
Apr 21, 2007, 1:30 PM MDT
In force
55 min
Issued by
the Storm Prediction Center
All 32 counties

Sedgwick County, CO, Arthur County, NE, Cherry County, NE, Deuel County, NE, Garden County, NE, Grant County, NE, Hooker County, NE, Keith County, NE, Keya Paha County, NE, Logan County, NE, McPherson County, NE, Thomas County, NE, Beadle County, SD, Brown County, SD, Brule County, SD, Buffalo County, SD, Clark County, SD, Day County, SD, Edmunds County, SD, Faulk County, SD, Hand County, SD, Hughes County, SD, Hyde County, SD, Jerauld County, SD, Jones County, SD, Lyman County, SD, Mellette County, SD, Potter County, SD, Spink County, SD, Sully County, SD, Todd County, SD, Tripp County, SD

The radar

The North Platte radar (KLNX), 173 km from the middle of the area, began a volume at 18:40 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.

The nearest sounding before it

Aberdeen, SD (KABR), launched 12:00Z, 6.6 hours before the alert went out and 207 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, Aberdeen, SD at 12:00Z on 2007-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 298 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, Aberdeen, SD at 12:00Z on 2007-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 72 square meters per square second.19395878Sfc1 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
298 J/kg
Mixed-layer CIN
-40 J/kg
Mixed-layer LCL
743 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
72 m²/s²
0-3 km storm-relative helicity
80 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.

IssuedProductOfficeCountiesLasted
Apr 21, 12:57 PM MDTTornado WatchSPCPhillips, Sedgwick9 hr
Apr 21, 1:44 PM MDTMesoscale DiscussionSPCBaca, Bent, Cheyenne, Kiowa, Kit Carson, Lincoln and 1 more91 min
Apr 21, 2:10 PM MDTTornado WatchSPCBaca, Bent, Cheyenne, Kiowa, Kit Carson, Prowers and 1 more7 hr
Apr 21, 4:57 PM MDTMesoscale DiscussionSPCPhillips, Sedgwick2 hr
Apr 21, 5:10 PM MDTMesoscale DiscussionSPCBaca, Bent, Cheyenne, Kiowa, Kit Carson, Prowers and 1 more2 hr
Apr 20, 7:45 PM MDTSevere Thunderstorm WatchSPCBlaine, Boyd, Brown, Chase, Cherry, Custer and 19 more5 hr
Apr 21, 12:31 AM MDTMesoscale DiscussionSPCBoyd59 min
Apr 21, 5:11 AM MDTMesoscale DiscussionSPCFrontier, Hitchcock, Red Willow2 hr
Apr 20, 9:56 PM MDTMesoscale DiscussionSPCAurora, Beadle, Bennett, Brown, Brule, Buffalo and 27 more2 hr
Apr 21, 1:30 PM MDTTornado WatchSPCAurora, Beadle, Bon Homme, Brookings, Brown, Brule and 38 more8 hr
Apr 21, 5:20 PM MDTMesoscale DiscussionSPCAurora, Beadle, Brown, Brule, Buffalo, Campbell and 32 more115 min

Nearby

Mesoscale Discussions in South Dakota, 2007Mesoscale Discussions in Nebraska, 2007Mesoscale Discussions in Colorado, 2007Every mesoscale discussion in 2007

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.