Alert archive / South Dakota / Severe Thunderstorm Watches in 2017

Severe Thunderstorm Watch 466

August 25, 20179 counties in Nebraska; 29 counties in South Dakota

The Storm Prediction Center issued this severe thunderstorm watch at Aug 25, 2017, 3:38 PM CDT for 9 counties in Nebraska; 29 counties in South Dakota. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Aug 25, 2017, 3:38 PM CDT (20:38 UTC)
Expired
Aug 25, 2017, 11:00 PM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
65 kt
All 38 counties

Antelope County, NE, Boyd County, NE, Brown County, NE, Cedar County, NE, Holt County, NE, Keya Paha County, NE, Knox County, NE, Pierce County, NE, Rock County, NE, Aurora County, SD, Beadle County, SD, Bon Homme County, SD, Brookings County, SD, Brule County, SD, Buffalo County, SD, Charles Mix County, SD, Clark County, SD, Davison County, SD, Douglas County, SD, Faulk County, SD, Gregory County, SD, Hand County, SD, Hanson County, SD, Hutchinson County, SD, Hyde County, SD, Jerauld County, SD, Kingsbury County, SD, Lake County, SD, Lyman County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Spink County, SD, Tripp County, SD, Turner County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 167 km from the middle of the area, began a volume at 20:38 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
10%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
60%

Warnings issued inside it

15 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Aug 25, 4:36 PM CDTSevere Thunderstorm WarningUNRTripp54 min
Aug 25, 5:12 PM CDTSevere Thunderstorm WarningUNRTripp63 min
Aug 25, 5:23 PM CDTSevere Thunderstorm WarningABRClark, Codington, Day52 min
Aug 25, 5:32 PM CDTSevere Thunderstorm WarningFSDBrule58 min
Aug 25, 5:42 PM CDTSevere Thunderstorm WarningFSDBrule, Charles Mix, Gregory63 min
Aug 25, 5:43 PM CDTSevere Thunderstorm WarningUNRTodd, Tripp25 min
Aug 25, 5:47 PM CDTSevere Thunderstorm WarningABRLyman43 min
Aug 25, 5:47 PM CDTTornado WarningABRClark, Codington, Day12 min
Aug 25, 6:22 PM CDTSevere Thunderstorm WarningLBFKeya Paha38 min
Aug 25, 6:36 PM CDTSevere Thunderstorm WarningFSDBeadle, Kingsbury, Miner, Sanborn39 min
Aug 25, 6:38 PM CDTSevere Thunderstorm WarningLBFKeya Paha22 min
Aug 25, 6:48 PM CDTSevere Thunderstorm WarningFSDAurora, Davison, Jerauld, Sanborn57 min
Aug 25, 7:00 PM CDTSevere Thunderstorm WarningFSDBrookings, Kingsbury, Lake, Miner45 min
Aug 25, 7:01 PM CDTSevere Thunderstorm WarningLBFCherry, Keya Paha44 min
Aug 25, 7:28 PM CDTSevere Thunderstorm WarningFSDLake, McCook, Miner, Minnehaha47 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Aberdeen, SD (KABR), launched 12:00Z, 8.6 hours before the alert went out and 124 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 2017-08-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2017-08-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 36 square meters per square second.1939Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
742 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
36 m²/s²
0-3 km storm-relative helicity
134 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 25, 2:57 PM CDTMesoscale DiscussionSPCAntelope, Boyd, Cedar, Holt, Keya Paha, Knox and 1 more3 hr
Aug 25, 5:58 PM CDTMesoscale DiscussionSPCAntelope, Boyd, Brown, Cedar, Holt, Keya Paha and 3 more2 hr
Aug 25, 3:46 PM CDTMesoscale DiscussionSPCButte, Custer, Lawrence, Oglala Lakota89 min

Nearby

Severe Thunderstorm Watches in South Dakota, 2017Severe Thunderstorm Watches in Nebraska, 2017Every severe thunderstorm watch 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.