Alert archive / South Dakota / Mesoscale Discussions in 2007

Mesoscale Discussion 1523

July 18, 20074 counties in Nebraska; 16 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 18, 2007, 4:15 PM CDT for 4 counties in Nebraska; 16 counties in South Dakota. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jul 18, 2007, 4:15 PM CDT (21:15 UTC)
Expired: Jul 18, 2007, 6:45 PM CDT
In force: 3 hr
Issued by: the Storm Prediction Center

Counties Boyd County, NE, Cedar County, NE, Dixon County, NE, Knox County, NE, Aurora County, SD, Bon Homme County, SD, Brule County, SD, Charles Mix County, SD, Clay County, SD, Davison County, SD, Douglas County, SD, Gregory County, SD, Hanson County, SD, Hutchinson County, SD, Lincoln County, SD, McCook County, SD, Minnehaha County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 121 km from the middle of the area, began a volume at 21:14 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 535Jul 18, 6:00 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 9.3 hours before the alert went out and 215 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: 454 J/kg
Mixed-layer CIN: -468 J/kg
Mixed-layer LCL: 1897 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 89 m²/s²
0-3 km storm-relative helicity: 129 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
Jul 18, 1:51 PM CDT	Mesoscale Discussion	SPC	Cherry, Dawes, Keya Paha, Sheridan	54 min
Jul 18, 6:05 PM CDT	Severe Thunderstorm Watch	SPC	Blaine, Boyd, Brown, Cherry, Garden, Garfield and 9 more	3 hr
Jul 17, 11:24 PM CDT	Mesoscale Discussion	SPC	Lincoln, Turner, Union	96 min
Jul 18, 12:47 PM CDT	Mesoscale Discussion	SPC	Lincoln, Minnehaha	2 hr
Jul 18, 2:53 PM CDT	Severe Thunderstorm Watch	SPC	Bennett, Butte, Custer, Fall River, Haakon, Hughes and 11 more	7 hr

Nearby

Mesoscale Discussions in South Dakota, 2007 Mesoscale Discussions in Nebraska, 2007 Every 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.