A supercell thunderstorm moved from west of Mandan, northeastward to just north of Bismarck during the early to mid-evening hours of Saturday, June 18th 2011. Nickel to quarter size hail was reported near Mandan, along with very heavy downpours, with one report of an inch of rain in ten minutes.
The most interesting part of this storm was its visual appearance, exhibiting classic supercell characteristics such as the striations of the mesocyclone, rain free base, and at times well defined rotation at the base of the mesocyclone (updraft of the storm). No funnel clouds formed with this storm, and no tornados. Below you will find photographs of the storm, along with radar imagery.
Although a well defined 'hook' echo was seen by National Weather Service Doppler Radar, the associated velocity data showed little low level circulation for the duration of this storm, indicating a low tornadic threat. A strong mid-level circulation (associated with the storm's mesocyclone) was depicted.
Radar image 1 is from 659 PM CDT. Radar image 2 is from 712 PM CDT.
Radar image 3 is from 722 PM CDT.