Areas of moderate to heavy snow and gusty to high winds are expected across the Northern Plains, Upper Midwest and Great Lakes. Patchy areas of light rain/freezing rain may develop along the rain-snow line over parts of the Northern Plains into the morning. A mix of light snow and freezing rain or drizzle is possible in the central Appalachians that may impact the morning commute. Read More >
Overview
During the evening of June 21, 2015 a supercell traveled across Harding, Perkins, and Ziebach Counties in northwestern South Dakota, bringing large hail, strong winds, and six tornadoes. Hail to the size of baseballs was reported 7 miles southeast of Meadow with numerous reports of golfball size hail near Bison and Meadow. Eyewitness spotter and chaser reports confirmed six distinct touchdowns with this supercell. The tornadoes remained in mainly rural areas of Perkins and Ziebach Counties with little to no damage being reported.
Tracks for all six reported tornadoes.
Tornadoes:
Tornado - North-Northwest of Prairie City, SD
Track Map |
Tornado - Northeast of Prairie City, SD
Track Map |
Tornado - East of Bison, SD
Track Map |
Tornado - North of Chance, SD
Track Map |
Tornado - Northeast of Chance, SD
Track Map |
Tornado - Southwest of Glad Valley, SD
Track Map |
The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:
EF0 Weak 65-85 mph |
EF1 Moderate 86-110 mph |
EF2 Significant 111-135 mph |
EF3 Severe 136-165 mph |
EF4 Extreme 166-200 mph |
EF5 Catastrophic 200+ mph |
Photos
All photos below were provided courtesy of Roger Hill.
Tornado #1 looking east-southeast from about 6 miles east of Ralph, SD | Tornado #5 looking north-northeast from about 5 miles south-southwest of Meadow, SD | Tornado #6 looking north-northeast from near Faith, SD at 8:50 pm MDT (about 20 miles away from the tornado) | Supercell thunderstorm looking north-northeast from near Faith, SD at 8:52 pm MDT |
Radar
Tornado track as approximated by Doppler radar derived rotation | Radar reflectivity (left) and velocity (right) of the tornado near Meadow at 8:03 pm MDT |
Storm Reports
PRELIMINARY LOCAL STORM REPORT...SUMMARY NATIONAL WEATHER SERVICE RAPID CITY SD 1001 AM MDT TUE JUN 23 2015 ..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON... ..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.... ..REMARKS.. 0656 PM TORNADO 10 SW LODGEPOLE 45.71N 102.81W 06/21/2015 PERKINS SD TRAINED SPOTTER ROPED OUT AND LIFTED AROUND 720PM JUST EAST OF HIGHWAY 75 AND NORTH OF HIGHWAY 20. 0700 PM FUNNEL CLOUD 7 SW LODGEPOLE 45.75N 102.78W 06/21/2015 PERKINS SD TRAINED SPOTTER 0740 PM TORNADO 3 ENE BISON 45.54N 102.40W 06/21/2015 PERKINS SD TRAINED SPOTTER LARGE BOWL SHAPED TORNADO TOUCHED DOWN FOR ABOUT TEN MINUTES 0806 PM TORNADO 4 SW MEADOW 45.49N 102.27W 06/21/2015 PERKINS SD TRAINED SPOTTER ELEPHANT TRUNK TORNADO ON GROUND FOR AROUND 5 MINUTES. 0850 PM TORNADO 7 WSW GLAD VALLEY 45.36N 101.92W 06/21/2015 ZIEBACH SD TRAINED SPOTTER SLENDER ROPE ON THE GROUND FOR ABOUT 2 MINUTES. THE STORM REPORTS LISTED BELOW ARE IN DESCENDING ORDER AND MAY NOT NECESSARILY BE THE FINAL STORM REPORTS. HAIL REPORTS LISTED BY SIZE (INCHES) SIZE LOCATION ST COUNTY TIME ------ ----------------------- -- -------------- ------- 2.75 7 SE MEADOW SD PERKINS 0815 PM LASTED 15 MINUTES 2.00 8 ESE MEADOW SD PERKINS 0813 PM 2.00 6 S LODGEPOLE SD PERKINS 0707 PM FOUND NUMEROUS GOLF BALL SIZE HAIL STONES IN YARD 30 MINUTES AFTER THE STORM PASSED THROUGH. 1.75 4 NW MEADOW SD PERKINS 0740 PM 1.50 9 NNE ALVA WY CROOK 1100 PM 1.00 9 NE LADNER SD HARDING 0620 PM LASTED 5 MINUTES TSTM WIND REPORTS LISTED BY SPEED (MPH) SPEED LOCATION ST COUNTY TIME ------ ----------------------- -- -------------- ------- 70.00 8 N HAMILL SD TRIPP 0145 AM 70.00 8 ENE BELVIDERE SD JACKSON 0145 AM 70.00 9 NNW CREIGHTON SD PENNINGTON 1235 AM LARGE TREES BLOWN DOWN...SMALL HAIL LASTED 15 MIN 62.00 2 ENE COTTONWOOD SD JACKSON 0110 AM 61.00 2 ENE SHERIDAN LAKE SD PENNINGTON 1210 AM TIME ESTIMATED FROM RADAR 60.00 11 NNE WOOD SD MELLETTE 0225 AM 60.00 6 NE OTTUMWA SD HAAKON 0115 AM 60.00 7 N BELVIDERE SD JACKSON 1230 AM 60.00 3 SE DOWNTOWN SPEARFISH SD LAWRENCE 1130 PM 3 DIAMETER TREE LIMBS KNOCKED OFF TREES 60.00 6 W ALADDIN WY CROOK 1115 PM LIVE TREE LIMBS OF 1 TO 3 IN DIAMETER RIPPED OFF TREES FROM WIND 60.00 13 W LODGEPOLE SD PERKINS 0655 PM
Environment
NWS Rapid City balloon information showed a very unstable air mass with strong vertical wind shear. The surface map showed dewpoints in the mid 60s feeding into the area.
Sounding for Rapid City at 6 pm MDT 21 June 2015 (00z the 22nd) | Hodograph for Rapid City at 6 pm MDT 21 June 2015 (00z the 22nd) | Surface map valid 6 pm MDT 21 June 2015 |
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