When a large dust storm rolled through Phoenix in July 2011, it was called a "100-year event”. The storm rose a mile high with a leading edge 100 miles across. It traveled 150 miles with peak gusts at 50 mph. Life-long residents were astonished having never witnessed such a storm.
Last week on March 11, a dust storm twice as high barreled over five states. With peak gusts at 60 mph, visibility was reduced to zero. Satellite imagery shows huge columns of dust streaming out of Colorado and Kansas and into Texas, Oklahoma and New Mexico. A dramatic aerial photograph taken above Amarillo Texas shows the vast leading edge engulfing land nearly to the horizon.
Perhaps even more extraordinary is such a storm would develop during winter. With the southwest enduring a prolonged drought, and with California and cities in Arizona and Nevada having their warmest winters on record, only a massive influx of cold air could produce such an event.
Dust storms are created by powerful downdrafts that occur when cold air positioned over warm air rapidly descends and produces a strong outflow. This is often observed during thunderstorms.
On March 11, an enormous cold front blasted southward across much of the central U.S., as indicated by the surface level winds depicted in this image provided by earth.nullschool.net. The frigid air from the north cascaded through the warm air below it, producing an enormous outflow.