Alert archive / South Dakota / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 354

July 8, 202112 counties in South Dakota

The Storm Prediction Center issued this severe thunderstorm watch at Jul 8, 2021, 3:49 PM MDT for 12 counties in South Dakota. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Jul 8, 2021, 3:49 PM MDT (21:49 UTC)
Expired
Jul 8, 2021, 10:00 PM MDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
3 in
Strongest gust expected
65 kt

Counties Bennett County, SD, Butte County, SD, Custer County, SD, Haakon County, SD, Harding County, SD, Jackson County, SD, Lawrence County, SD, Meade County, SD, Oglala Lakota County, SD, Pennington County, SD, Perkins County, SD, Ziebach County, SD

The radar

The Rapid City radar (KUDX), 110 km from the middle of the area, began a volume at 21:49 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.

What SPC expected

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

Two or more tornadoes
20%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
60%
One or more gusts of 65 knots or more
60%
Ten or more severe hail reports
60%
One or more hailstones of 2 inches or more
60%
Six or more combined severe hail and wind reports
95%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jul 8, 4:29 PM MDTSevere Thunderstorm WarningUNRButte, Meade61 min
Jul 8, 5:26 PM MDTSevere Thunderstorm WarningUNRCuster, Meade, Pennington64 min
Jul 8, 5:30 PM MDTSevere Thunderstorm WarningUNRHarding, Perkins26 min
Jul 8, 6:14 PM MDTSevere Thunderstorm WarningUNRCuster, Jackson, Oglala Lakota, Pennington61 min
Jul 8, 6:39 PM MDTSevere Thunderstorm WarningUNRHarding, Perkins66 min
Jul 8, 6:58 PM MDTSevere Thunderstorm WarningUNRPerkins, Ziebach47 min
Jul 8, 7:10 PM MDTSevere Thunderstorm WarningUNRBennett, Jackson, Oglala Lakota65 min
Jul 8, 7:42 PM MDTSevere Thunderstorm WarningUNRPerkins, Ziebach63 min
Jul 8, 7:43 PM MDTSevere Thunderstorm WarningUNRPerkins62 min
Jul 8, 8:32 PM MDTSevere Thunderstorm WarningUNRHaakon, Ziebach58 min
Jul 8, 8:34 PM MDTSevere Thunderstorm WarningUNRMeade, Perkins, Ziebach56 min
Jul 8, 9:28 PM MDTSevere Thunderstorm WarningUNRHaakon, Meade, Ziebach62 min
Jul 8, 9:30 PM MDTSevere Thunderstorm WarningUNRHaakon, Ziebach24 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

Rapid City, SD (KUNR), launched 12:00Z, 9.8 hours before the alert went out and 117 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, Rapid City, SD at 12:00Z on 2021-07-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 143 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, Rapid City, SD at 12:00Z on 2021-07-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 45 square meters per square second.1939587897Sfc1 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
143 J/kg
Mixed-layer CIN
-535 J/kg
Mixed-layer LCL
1257 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
45 m²/s²
0-3 km storm-relative helicity
185 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
Jul 7, 7:15 PM MDTMesoscale DiscussionSPCCuster, Fall River, Lawrence2 hr
Jul 8, 2:34 PM MDTMesoscale DiscussionSPCButte, Harding, Perkins86 min
Jul 8, 4:56 PM MDTMesoscale DiscussionSPCButte, Harding, Meade, Perkins, Ziebach2 hr

Nearby

Severe Thunderstorm Watches in South Dakota, 2021Every severe thunderstorm watch in 2021

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.