A rolling dust storm, known as a haboob, swept through the Coachella Valley in California on Thursday.
According to AccuWeather.com Meteorologist Ken Clark, haboobs form when "outflow downdrafts from thunderstorms cause strong winds that pick up dust."
Clark said that a big complex in Southern California occurred in the late afternoon on Thursday, with only a trace amount of actual rain recorded for the drought-parched region.
AccuWeather.com Meteorologist Heather Waldman has more details here:
HPWREN web-cam showing a dust storm moving into #Coachella Valley and #AnzaBorrego desert. Vis is near 0. #cawx pic.twitter.com/JDxWP247q6— NWS San Diego (@NWSSanDiego) August 21, 2014