Alert archive / South Dakota / Mesoscale Discussions in 2017
Mesoscale Discussion 1540
The Storm Prediction Center issued this mesoscale discussion at Aug 21, 2017, 11:12 AM CDT for 4 states. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Aug 21, 2017, 11:12 AM CDT (16:12 UTC)
- Expired
- Aug 21, 2017, 12:45 PM CDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
All 30 counties
Lyon County, IA, Plymouth County, IA, Sioux County, IA, Rock County, MN, Boyd County, NE, Cedar County, NE, Dakota 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, Jerauld County, SD, Lincoln County, SD, Lyman County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Sanborn County, SD, Tripp County, SD, Turner County, SD, Union County, SD, Yankton County, SD
The radar
The Sioux Falls radar (KFSD), 142 km from the middle of the area, began a volume at 16:11 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, 4.2 hours before the alert went out and 188 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1701 m above ground
- 0-6 km bulk shear
- 44 kt
- 0-1 km storm-relative helicity
- 16 m²/s²
- 0-3 km storm-relative helicity
- 21 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.1
The text
As transmitted.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 20, 11:14 PM CDT | Mesoscale Discussion | SPC | Adair, Audubon, Boone, Calhoun, Carroll, Cass and 15 more | 91 min |
| Aug 21, 11:33 AM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 6 more | 7 hr |
| Aug 21, 2:35 PM CDT | Mesoscale Discussion | SPC | Audubon, Boone, Buena Vista, Calhoun, Carroll, Cherokee and 27 more | 85 min |
| Aug 21, 5:31 AM CDT | Mesoscale Discussion | SPC | Hand, Hughes, Hyde, Potter, Stanley, Sully | 89 min |
| Aug 21, 8:27 AM CDT | Mesoscale Discussion | SPC | Aurora, Beadle, Brule, Buffalo, Charles Mix, Davison and 16 more | 2 hr |
| Aug 21, 8:55 AM CDT | Severe Thunderstorm Watch | SPC | Aurora, Brule, Buffalo, Charles Mix, Davison, Douglas and 8 more | 5 hr |
Nearby
Mesoscale Discussions in South Dakota, 2017Mesoscale Discussions in Nebraska, 2017Mesoscale Discussions in Iowa, 2017Every mesoscale discussion in 2017
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.