STORM2K

SPECIAL WEATHER STATEMENT...CORRECTION
NATIONAL WEATHER SERVICE JACKSON MS
1250 PM CDT TUE MAR 20 2007

..NUMEROUS DUST DEVILS DEVELOPING ACROSS THE DELTA THIS AFTERNOON:
DUE TO THE VERY DRY AND WARM WEATHER WE HAVE EXPERIENCED COMBINING
WITH NUMEROUS FARMERS PLOWING THERE FIELDS DUST DEVILS HAVE BEEN
PROMINENT ACROSS THE DELTA TODAY. THE PLOWING OF FIELDS AND LACK OF
RAIN HAVE MADE FOR VERY DRY AND LOOSE SOIL. AS PARCELS GET WARMER
THAN THE SURROUNDING AIR IT BEGINS TO RISE. AS THESE AIR PARCELS
RISE THEY BEGIN TO ROTATE THUS PICKING UP SOME OF THIS LOOSE
SOIL...AND BAM YOU HAVE A DUST DEVIL. THIS COULD BE THE CASE OVER
THE NEXT FEW DAYS AS WE EXPECTING TO GET EVEN WARMER WITH NO RAIN
EXPECTED UNTIL LATE THIS WEEKEND OR EVEN NEXT WEEK.

THERE ARE NO SERIOUS CONCERNS WITH THESE AS THE WINDS ARE LIKELY
LESS THAN 25 MPH. THE ONLY PROBLEM COULD BE TO MOTORISTS WHERE THEY
MIGHT CROSS ROADS AND VERY BRIEFLY LOWER VISIBILITIES.

We dont see many here i guess. LOL I reported one last year that I saw cross the highway and it was a stronger one: im guessing a brief 70 MPH. I lasted for about 7 seconds but knocked a few limbs down and it was cool to see.

Wow, I've never seen that around here before.

I didn't see any today, but after I read that I asked my dad if he saw any this afternoon and he said he saw one or two.


It has been so warm lately!!

Here is a video of one of those stronger dust devils that can occassionally occur...


[youtube]http://www.youtube.com/watch?v=tOITKe-H6HE[/youtube]

In rare instances (such as above), they can even produce damage similar to an F0 tornado.

Ive seen that vid before. It is amazing. Ive seen swirls of leaves and dust but not at that scale. Was cool being in the center of it. Pretty windy!

Actually the larger and more intense devils such as we see in Arizona can cause F1 damage. Locally, winds in devils have been recorded at over 80 mph while in NM they have been measured at close to 100 mph. Peak here at my house in a devil was 69 mph. I have a photo showing a garden shed destroyed by a devil.

Steve

Aslkahuna wrote:Actually the larger and more intense devils such as we see in Arizona can cause F1 damage. Locally, winds in devils have been recorded at over 80 mph while in NM they have been measured at close to 100 mph. Peak here at my house in a devil was 69 mph. I have a photo showing a garden shed destroyed by a devil.

Steve

That's interesting to know, thanks for sharing that. Sure wouldn't want to be caught in one of those devils!

What exactly causes a dust devil?

When I had visited NM a few years back, I did see a few mini dust devils - pretty cool!

Dave and I, along with another couple, got nailed by a dust devil in NM in early July 1999. We were on motorcycles and there was no time to take evasive action. NOT fun.

Dust devils form from intense heating of the ground which heats the overlying air giving rise to thermals which rise rapidly. Cooler air rushes in to replace the rising and the combination of surface roughness and temperature contrast leads to rotation. The inrushing winds pick up dust and surface debris which entrains into the vortex that develops around the thermal. Being less storng than tornadoes generally, dust devils are excellent subjects for the study of small scale vortices in the lower atmosphere and exhibit the same variety of forms as do tornadoes-including mulitple vortex devils. Should be noted that in the Spring and Summer here in AZ the ground temperatures can range from 160 to 200+ degrees F.

Steve

I saw a couple of dust devils this week in Tampa. They are reconstructing a golf course and one came across the golf course and crossed the road in front of me. The other one was across the street on another part of the golf course. I'm betting we have another record March with no rain this year.

Ive seen a few at the beach and almost got run over last year by one coming down my street, but it dissipated.