A map of the location of tornadoes over southeast South Dakota between 4 pm and 7 pm CDT Saturday September 16, 2006. Click on the map for a larger view.
Seven tornadoes touched down over southeast South Dakota during the late afternoon of 16 September 2006. The strongest tornado occurred in McCook County approximately from 4:10 pm and 4:30 pm CDT. This tornado damaged several buildings and was rated F2. The same supercell moved into northwest Minnehaha County and produced an F1 tornado northeast of Colton South Dakota between 4:54 pm and 4:57 pm CDT. Damage was reported to some buildings as well as power lines being down. Finally, four F0 tornadoes were reported with other supercells which formed during the late afternoon. No damage was reported with these storms.
Visible satellite picture from 2:55 pm CDT 16 September 2006. Overlaid is the surface observations from the same time as well as the location of the surface low (red L), the dry line (dashed brown line), and a warm front (dashed red line).
As thunderstorms moved northeast of the region Saturday morning, skies cleared across Nebraska and Iowa. A narrow band of clouds extended from north central Nebraska through southeast South Dakota. These clouds persisted through the mid afternoon. As a result, a warm front formed due to the difference in the amount of sunshine as there was not a significant wind shift across the front. Where partly to mostly sunny skies occurred, temperature rose into the mid 80s while temperatures remained in the mid 70s under the clouds north of Sioux Falls. At the same time, a dryline extended from near Yankton, South Dakota into eastern Nebraska. Dew points east of the dry line were in the mid to upper 60s while west of the dry line dew points fell into 40s and 50s.
Radar reflectivity image from 5:26 pm CDT 16 September 2006. Locations of supercells at that time are annotated on the image.
The first supercell of the afternoon formed near the intersection of the dry line and warm front in south central South Dakota. By late afternoon, several supercells were located across southeast South Dakota. On the image above, there are 3 mature supercells - all of which produced tornadoes during their lifetime - one forming supercell and one dissipating supercell (which had produced a tornado). These storms also produced large hail and damaging winds during the afternoon and evening.
For more information on tornadoes that occurred this today, click the links below.