Since the weekend, tornado activity has been suppressed. Aside from a small outbreak of tornadoes (15 reports) in south Texas yesterday, only four tornado reports have been logged by NOAA’s Storm Prediction Center. But the atmosphere has been turbulent in spots, kicking up and swirling dust in the Southwest and spinning up vortices over the waters of Louisiana and Alabama. Some eye-popping imagery tells the tale...
Waterspouts in the Gulf Coast states
On Wednesday, NOAA employee Tim Osborn photographed twin waterspouts just offshore Grand Isle, Louisiana.
Waterspouts are defined as tornadoes over water but can form under different circumstances - either in fair weather or in tornadic thunderstorms. NOAA explains:
The tornadic waterspouts may often begin as tornadoes over land and then move over water. They also form in severe thunderstorms over a body of water. They can wreak havoc with high winds, hail, and dangerous lightning.
Fair weather waterspouts develop in calmer weather. They form only over open water, developing at the surface and actually climbing skyward towards the clouds.
Multiple waterspouts were also photographed in Mobile Bay in southern Alabama Wednesday morning.
Phoenix dust storm or haboob
While waterspouts swirled over the Gulf of Mexico,outflow winds from a thunderstorm in the vicinity of Phoenix blew up a dust storm or haboob. Photographer Mike Olbinski captured this amazing video which does a wonderful job of illustrating how the dust storm formed Wednesday:
Related: Inside the Phoenix, Arizona dust storm, or “haboob” (July 6, 2011)
Las Vegas dust devils
Two days before the waterspout and dust storm spectacles, destructive dust devils swept through the Las Vegas valley in Nevada. The National Weather Service documented at least three “well-developed” dust devils that formed Monday, May 7. They produced winds up to 55-60 mph and caused some minor structural damage.
What’s a dust devil? Here’s the NWS’ excellent description:
A dust devil is a rotating column of air that forms as a result of intense surface heating. During the daytime radiation from the sun heats the ground and the warm ground in turn heats a thin layer of air directly above the ground. Since this thin layer of heated air is warmer and less dense than the air above it, it tends to rise. Under the right conditions, a column of rapidly rising air may develop and begin to spin. As the column is stretched vertically it begins to rotate faster - resulting in a dust devil as it picks up dust, sand and debris from the ground. How does a dust devil compare to a tornado? Both are rotating columns of air; however, dust devils form under clear skies, while tornadoes are associated with a parent thunderstorm.
You can learn more about dust devils and Monday’s dust devil event near Vegas here: Destructive Dust Devils In The Las Vegas Valley On May 7, 2012