Mammatus Clouds Above Hot Springs, South Dakota

Photographer: Tara Butler
Summary Author: Jim Foster   Tara Butler  

The photo above shows sunlit mammatus clouds as observed following a short rainstorm in Hot Springs, South Dakota on the evening of June 16, 2008. Weather prior to the storm had been sunny and warm, but during the summer months, thunderstorms often develop in the afternoon over the Black Hills range in western South Dakota. Mammatus clouds tend to form as a result of cold air downdrafts on the underside of cumulonimbus anvils. Though they're not an indicator of severe weather, these odd looking pouch-like clouds command our attention. 

Photo details: Canon PowerShot G6 camera; in Auto Mode; taken at 8:42 p.m. (local time).