CNN CNN Saturday Morning July 13, 2013 14:44:00
It happened yesterday in phoenix. phoenix though does see these on average about three a year between summer, between june and september. so here is what happens. what you need first is a dusty terrain which we certainly have around phoenix and arizona. the second ingredient is a thunderstorm. within a thunderstorm there are updrafts and there are downdrafts. the updraft happens, then the downdrafts happen and the downdraft creates this gust front and the gust front is what kicks up all the dust. when you look at this, it's like a wall of dust. it can be pretty scary coming at you almost in sl...
Source: archive.org