Phoenix’s Big HaboobPosted: July 7, 2011
From EarthSky.org: Ken Waters, from the National Weather Service in Phoenix, explains how dust storms form, and why it is that Tuesday’s storm in Phoenix got so incredibly big:
Dust storms form from monsoon thunderstorms that form up in the afternoon. When the severe storms reach their full maturity, they produce what we call a microburst, which is like a very rapidly descending burst of air that comes through the thunderstorm that actually puffs out, hits the ground, and then disperses away from the storm.
You can picture it like throwing a pebble into a lake – you get a wake that goes out in all directions. So it’s basically a very strong wind that goes out. You couple that with the fact many of these areas [around Phoenix] have a lot of dust on them and they haven’t had rain in 3-4 months. So there’s a lot of available dust. And it doesn’t take much wind to pick that up. And that’s what happened [Tuesday].