June 1-2, 2015 Visually Stunning Supercell, Softball Size Hail, and Flooding

Photos & Video

Storm from June 1, 2015

Hail near Piedmont, SD, around 7 pm MDT June 1, 2015 (photo by off-duty NWS employee Alex Calderon)

These photos were taken during the early morning of June 2, 2015 by off-duty NWS employee Alex Calderon.

Storm from June 2, 2015

A series of severe thunderstorms affected northeastern Wyoming and western South Dakota between 4 pm June 2, 2015 and the early morning of June 3, 2015. Up to golf ball size hail was reported along with wind gusts up to 70 mph. The time-lapse of the storm below was the one that produced golf ball size hail around 4:30 pm MDT 4 miles northeast of Rockerville, SD. The video is indicative of a low precipitation (LP) supercell during the initial stages of the thunderstorm.

Radar

June 1, 2015

A severe thunderstorm developed between Sturgis and Rapid City, SD, around 5:10 pm MDT on June 1, 2015. The storm moved very slowly to the south producing hail up to softball size in Piedmont, SD, around 6:55 pm. The storm weakened by 9 pm, but flooding continued overnight. Here are two radar images from 6:38 pm MDT when the storm was very intense.

June 1, 2015 6:37 pm MDT 0.5 base reflectivity image	June 1, 2015 6:37 pm MDT 0.5 3-dimensional view of supercell

Storm Reports

Storms Reports for June 1, 2015

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
 ------  -----------------------  --  --------------   -------
  4.50   PIEDMONT                 SD  MEADE            0655 PM
  2.50   1 NW PIEDMONT            SD  MEADE            0712 PM
  2.50   PIEDMONT                 SD  MEADE            0655 PM
                 MILE MARKER 44 ON I90
  2.00   1 NW PIEDMONT            SD  MEADE            0620 PM
  1.75   1 ESE PIEDMONT           SD  MEADE            0735 PM
  1.75   BLACK HAWK               SD  MEADE            0717 PM
  1.75   PIEDMONT                 SD  MEADE            0655 PM
  1.75   2 S TILFORD              SD  MEADE            0520 PM
  1.50   1 NW PIEDMONT            SD  MEADE            0613 PM
  1.25   1 NW PIEDMONT            SD  MEADE            0550 PM
  1.25   TILFORD                  SD  MEADE            0510 PM
  1.00   7 E CREIGHTON            SD  PENNINGTON       0943 PM
  1.00   3 N DOWNTOWN BELLE FOUR  SD  BUTTE            0922 PM
  1.00   PIEDMONT                 SD  MEADE            0626 PM
                 EXIT 44 AND I-90 LOTS OF HAIL
  1.00   PIEDMONT                 SD  MEADE            0619 PM
                 HEAVY RAIN... SOME STREETS OVERFLOWING WATER
                 PONDING INTO GRASSY AREAS
  0.88   11 NW DOWNTOWN RAPID CI  SD  MEADE            0816 PM
                 OVER AN INCH OF RAIN
  0.25   1 NW PIEDMONT            SD  MEADE            0550 PM

TSTM WIND REPORTS LISTED BY SPEED (MPH)

 SPEED   LOCATION                 ST  COUNTY           TIME
 ------  -----------------------  --  --------------   -------
 65.00   2 NNW SAINT ONGE         SD  LAWRENCE         1000 PM
 60.00   9 N BOX ELDER            SD  MEADE            0800 PM

Storms Reports for June 2, 2015

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
 ------  -----------------------  --  --------------   -------
  1.75   3 N ROCKERVILLE          SD  PENNINGTON       0432 PM
  1.75   4 NE ROCKERVILLE         SD  PENNINGTON       0430 PM
  1.25   4 NE ROCKERVILLE         SD  PENNINGTON       0430 PM
  1.00   4 S DOWNTOWN RAPID CITY  SD  PENNINGTON       0436 PM
  0.88   ROCKERVILLE              SD  PENNINGTON       0620 PM
  0.88   ROCKERVILLE              SD  PENNINGTON       0442 PM
  0.75   3 N SHERIDAN LAKE        SD  PENNINGTON       0415 PM

TSTM WIND REPORTS LISTED BY SPEED (MPH)

 SPEED   LOCATION                 ST  COUNTY           TIME
 ------  -----------------------  --  --------------   -------
 70.00   9 ENE BELVIDERE          SD  JACKSON          1230 AM (JUNE 3, 2015)
 66.00   1 NE MIDLAND             SD  HAAKON           1230 AM (JUNE 3, 2015)
 62.00   10 ESE PINE HAVEN        WY  CROOK            0825 PM
                 62 MPH WIND GUSTS FROM 825 TO 830 PM.
 60.00   3 WNW WASTA              SD  PENNINGTON       1050 PM
 60.00   1 E DOWNTOWN RAPID CITY  SD  PENNINGTON       1008 PM
 60.00   2 ENE WESTON             WY  CAMPBELL         0735 PM
 60.00   1 NW MARTIN              SD  BENNETT          0715 PM
 58.00   6 W PARMELEE             SD  TODD             0800 PM
 58.00   1 ESE MARTIN             SD  BENNETT          0715 PM
 57.00   4 SE SUNDANCE            WY  CROOK            0850 PM

Environment

June 1, 2015

NWS Rapid City balloon information showed a moderately unstable air mass with sufficient vertical wind shear for slow-moving supercells. The surface map showed dewpoints in the lower 60s on the eastern side of the Black Hills.

Sounding for Rapid City at 6 pm MDT 1 June 2015 (00z the 2nd)	Hodograph for Rapid City at 6 pm MDT 1 June 2015 (00z the 2nd)	Surface map valid 7 pm MDT 1 June 2015

June 2, 2015

Below is the 6 am balloon information for NWS Rapid City because the afternoon balloon release was not representative. However, this still showed a fairly unstable air mass, and afternoon surface dewpoints were in the upper 50s with a northerly wind. The result on this day was a supercell that formed farther south than the previous day, near Rockerville.

Sounding for Rapid City at 6 am MDT 2 June 2015	Hodograph for Rapid City at 6 am MDT 2 June 2015	Surface map valid 3 pm MDT 2 June 2015