Alert archive / South Dakota / Severe Thunderstorm Watches in 2017

Severe Thunderstorm Watch 215

May 15, 20175 states

The Storm Prediction Center issued this severe thunderstorm watch at May 15, 2017, 4:40 PM MDT for 5 states. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
May 15, 2017, 4:40 PM MDT (22:40 UTC)
Expired
May 16, 2017, 12:00 AM MDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2.5 in
Strongest gust expected
60 kt
All 25 counties

Carter County, MT, Custer County, MT, Fallon County, MT, Powder River County, MT, Adams County, ND, Bowman County, ND, Slope County, ND, Box Butte County, NE, Dawes County, NE, Sheridan County, NE, Sioux County, NE, Butte County, SD, Custer County, SD, Fall River County, SD, Harding County, SD, Lawrence County, SD, Meade County, SD, Oglala Lakota County, SD, Pennington County, SD, Perkins County, SD, Campbell County, WY, Crook County, WY, Goshen County, WY, Niobrara County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 129 km from the middle of the area, began a volume at 22:42 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
2%
Ten or more severe wind reports
20%
One or more gusts of 65 knots or more
10%
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
70%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 15, 5:14 PM MDTSevere Thunderstorm WarningUNRCampbell, Crook50 min
May 15, 5:18 PM MDTSevere Thunderstorm WarningCYSGoshen42 min
May 15, 5:49 PM MDTSevere Thunderstorm WarningUNRCampbell, Crook56 min
May 15, 5:59 PM MDTSevere Thunderstorm WarningUNRCampbell26 min
May 15, 6:05 PM MDTSevere Thunderstorm WarningBYZCuster25 min
May 15, 6:24 PM MDTSevere Thunderstorm WarningUNRWeston66 min
May 15, 6:30 PM MDTSevere Thunderstorm WarningBYZCarter60 min
May 15, 6:43 PM MDTSevere Thunderstorm WarningUNRCrook34 min
May 15, 6:55 PM MDTSevere Thunderstorm WarningUNRWeston65 min
May 15, 7:23 PM MDTSevere Thunderstorm WarningUNRWeston52 min
May 15, 9:54 PM MDTSevere Thunderstorm WarningUNRMeade66 min
May 15, 10:46 PM MDTSevere Thunderstorm WarningLBFSheridan44 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

Riverton, WY (KRIW), launched 12:00Z, 10.7 hours before the alert went out and 378 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, Riverton, WY at 12:00Z on 2017-05-15Temperature 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 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Riverton, WY at 12:00Z on 2017-05-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -80 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1899 m above ground
0-6 km bulk shear
62 kt
0-1 km storm-relative helicity
-80 m²/s²
0-3 km storm-relative helicity
79 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
May 15, 3:07 PM MDTMesoscale DiscussionSPCCarter, Custer, Powder River, Prairie113 min
May 15, 2:44 PM MDTSevere Thunderstorm WatchSPCDundy, Hitchcock, Red Willow7 hr
May 15, 4:58 PM MDTMesoscale DiscussionSPCAdams, Boone, Buffalo, Clay, Custer, Dawson and 23 more2 hr
May 15, 5:53 PM MDTSevere Thunderstorm WatchSPCAdams, Buffalo, Clay, Custer, Dawson, Fillmore and 20 more6 hr
May 15, 8:15 AM MDTMesoscale DiscussionSPCHutchinson, Lincoln, McCook, Minnehaha, Turner90 min

Nearby

Severe Thunderstorm Watches in South Dakota, 2017Severe Thunderstorm Watches in Wyoming, 2017Severe Thunderstorm Watches in Montana, 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.