Advise required on Chasing dust devils

[Stuart Robinson]

OK another hair brained plan of mine…

I want to see a dust devil - I am not talking about those Oklahoma wheat field spin ups, but the full blown dust devils that occur over the Nevada and south Carolina desserts – I have never seen a real big dust devil so I am planning a chase to photograph one in 2005.

So what I am looking for forecast wise?

I assume a hot hot surface with light winds aloft – hopefully with some sort of inversion at around 950mb

Also what time of year would be the best time to go…

So many questions can anyone help? – it is a big commitment for me to chase over in the USA (I live in the UK) and I really need to balance my trips between tornados (May) and Hurricanes (September).

BTW I would be looking for a chase pertner if any one is interested.

 

[mikegeukes]

The more arid areas of Arizona, California, Coloradao,
New Mexico, Nevada, extreme southwest Texas, Utah
are states that offer good viewing of dust devils.

Definition of a Dust Devil: Source: AMS

dust devil—A well-developed dust whirl; a small but vigorous whirlwind, usually of short duration, rendered visible by dust, sand, and debris picked up from the ground.

Dust devils occasionally are strong enough to cause minor damage (up to F1 on the Fujita scale). Diameters range from about 3 m to greater than 30 m; their average height is about 200 m, but a few have been observed as high as 1 km or more. They have been observed to rotate anticyclonically as well as cyclonically. Although the vertical velocity is predominantly upward, the flow along the axis of large dust devils may be downward. Large dust devils may also contain secondary vortices. Dust devils are best developed on a hot, calm afternoon with clear skies, in a dry region when intense surface heating causes a very steep lapse rate of temperature in the lowest 100 m of the atmosphere.

Some links, on dust devils (must be more out there)
DUST DEVILS
http://www.death-valley.us/article559.html
http://www.weatherquestions.com/What_are_d...dust_devils.htm
http://www.wrh.noaa.gov/Flagstaff/science/dustdvl.htm

DOPPLER-RADAR OBSERVATIONS OF DUST DEVILS IN TEXAS
Howard B. Bluestein, Christopher C. Weiss and Andrew L. Pazmany
http://ams.confex.com/ams/pdfpapers/63293.pdf

MATADOR DUST DEVIL PROJECT
http://www.lpl.arizona.edu/IMP/Matador/intro.html

UNWRAPPING THE WHIRLWIND; MEASURING NATURAL DUST DEVILS
http://gsa.confex.com/gsa/2004AM/finalprog...tract_80950.htm

Mike

 

[David Drummond]

Dude, we get some wicked dust devils here in west Texas that resemble in appearance like miniature wedge tornadoes, complete with multiple vortices! Some have been known to even do minor damage to small outbuildings.

I remember one time when I was doing a detailing on the chase van. One of those ALL DAY detailings. It was late in the afternoon and I was about done, putting on the final touches. Beautiful day, some fair weather CU floating around, but nice and sunny and light wind. I had all the doors open of course and had just put armor all on all the plastic.

Then it began....

From out of nowhere came the winds I had heard about only an ancient native american tales. Every piece of dirt in grass seem to fly in from blocks away as the unwarned massive dustdevil engulfed the wide open chase van. The devistation left in it's wake was enough to make even strong men weak in the knees....all that work...just....gone. :shock: The entire van was full of dirt and grass plastered to the fresh armor all.

This had a profound effect on me and even now, every time I clean the van, I keep an ever watchful eye out for another unexpected attack of the devil winds. :wink:

 

[Robert Dewey]

Dust devils are pretty cool...

I seen a pretty significant one here in MI a few years ago, of all places... I was sitting in the van at a bank, and across the street was a large construction area of nothing but very dry sandy type dirt. The temps were in the upper 90's with no humidity and very very calm winds. Then, I noticed it... A rather large funnel of dust formed, and headed straight for me... It was actually pretty wide, about 100 feet or so, but only about 75 feet tall (a mini-wedge, LOL). When it went over, winds actually gusted to 60-70mph, broke some small twigs off the trees, and pushed a few people to the ground (given the dust pelting them in the face). When it went over, the sunlight even dimmed quite a bit due to the dust... It then faded away over the parking lot, as it lost it's source of dust I suppose...

Quite interesting though, not as bad as Daves' story, LOL

 

[Tim Vasquez]

I've personally been cored by two western dust devils... one in Tucson at a swap meet and another when I worked on the Nevada Test Range. The first one turned into a column of merchandise and loose cash. The second one started as a whirling blender of tumbleweed (thankfully I was indoors). Both events were a hoot.

My own experience on the Nevada Test Site is that they had a very strong tendency to form right along cloud shadows.... probably it is some sort of differential heating that gets it started.

Tim

 

[Jeff Wear]

The best time of day to witness a dust devil would be sometime between about 11am and 3pm. I've noticed that they tend to form most in places and on days where the ground is heated unevenly. The biggest "dust devil outbreaks" I have witnessed occurred on days where there were scattered fair weather cumulus dotting the sky. When I lived in CA I also witnessed a lot of dust devils near boundaries between dry, plowed fields and grassy, irrigated fields.

Your best bet for chasing dust devils would probably be while you're here for your tornado chase vacation. May and June would be the best months for viewing dust devils in the southwestern US. If there is going to be a death ridge over the Plains for several days, a trip west in hopes to see dust devils would be reasonable - it takes about 10 hours to get from Amarillo to Phoenix. But David's right - you can probably see a dust devil in western Texas just as good as any as you would see further west....and I once witnessed a large dust devil while waiting for storms to fire in eastern New Mexico. There have also been dust devil/landspout hybrids that have been observed underneath small cumulus clouds developing on the dryline....Dr Lou Wicker got some great pics of one near Vernon TX in 1996......

http://thunder.nssl.noaa.gov/users/lwicker...Dust_Spout.html

 

[Shane Adams]

You want basically still, hot days. Also, doesn't hurt to have some type of geographical anomoli nearbye, like a small hill. On August 6, 2001, Scott Blair, Blake Michaleski, Eric Nguyen and myself chased them all day, from 11am-5pm, near the town of Paoli, OK just east of I-35. Granted these devils are nothing like what you might get in say, Kenya, but they are still impressive in their own right.

We noted that most of the smaller ones formed after a period of slowly increasing surface winds from a mean direction. The big ones formed whenever the winds would turn and become variable. I have extensive video of this chase, and we noted that all the devils (including the smallest ones) had some degree of multi-vortex structure. The range in size ran from a few inches in diameter to about 20 feet.

Probably the most incredible display was while a large devil was in progress, a small one formed north of it, and raced south right into the bigger one, getting absorbed as it did. Pretty cool stuff. Also, at least in the field we were at, there was very favorable set-up for sustained devils, as everyone that formed lasted until they moved out of the field and into grass. The field was about 200X400 yards.

I'll post a special page about this chase on my site the next time I do updates.

 

[David Drummond]

Dust devils are pretty cool...especially on down chase days. What sucks is some of the most spectacular ones I have seen I never had a damn camera with me. The last really good one we saw, we were on the south side of lubbock and it was on the southwest side...and HUGE! Looked for all the world like a tornado if you ignored the fact there was no cloud base above it, but I swear I could have filmed it without the cloud base area and you would have thought it was a tornado. By the time we worked around to where we could get a good picture it finally dissipated, but it lasted a good 20 minutes... (damn road contruction! :lol: )

One of the best ones I have seen was out near Meadow, TX southwest of Lubbock. This thing looked for all the world like that last F5 tornado in TWISTER, only on a smaller scale. Had the vortex "curls" rotating around it's sides and completely full of dirt, maybe 75 yards across. This was the largest one I ever witnessed. We followed it for probably a good 10 miles before it finally got in to some trees and grass and lost the battle. I would have given ANYTHING to have a video camera that day.

I agree with the others, May through August the best time to see them out here on the caprock is late morning through mid afternoon, usually on days with lower RH and some puffy CU floating around. I never made the corelation that Tim mentioned about the cloud shadows, I am going to have to watch for that now.

I remember Dr. Bluestein talking about the studies they did on them at the chaser convention earlier this year. If I remember right he said they had the same vorticity of tornadoes, but on a smaller scale and not near as powerful of course without the higher winds, but because they were a smaller entity they had similar vorticity. If I got that backwards, sorry, it's been a few months since hearing that. :wink:

 

[David Wolfson]

In this area, Stu, I'd suggest mid to late May. If you're lucky you'll be able to intercept mid-level meso troughs as they lift out over us for the dust devils and follow them through New Mexico onto the high plains for the supercells.

Small dust devils are pretty common almost year-around here; but as others have commented there are special conditions that make for the more impressive ones. You want some cyclonic vorticity and associated high lapse rates above ground level and some (but not too much) flow which is brought down to the surface by turbulent mixing from the thermals. The instability needs to be capped enough so as not to generate too many sun-hiding clouds. In other words, the dog days of June and later in the summer are too stable for good devils, contrary to what you'd think given maximum insolation, at least from my observation. And once there's been significant rain, the superheating of the surface soil is much less.

To my eyes, dust devils somewhat resemble tropical cyclones in that they extract a significant amount of their energy (although sensient rather than latent) from the surface material which they disturb, are warm-cored, and adversely affected by too much vertical shear.

I've seen the cloud shadow effect, but I think the shadows result from the conditions that make for good dust devils rather than being the cause of them.

 

[Gayla Drummond]

I remember one time when I was doing a detailing on the chase van. One of those ALL DAY detailings. It was late in the afternoon and I was about done, putting on the final touches. Beautiful day, some fair weather CU floating around, but nice and sunny and light wind. I had all the doors open of course and had just put armor all on all the plastic.

Then it began....

From out of nowhere came the winds I had heard about only an ancient native american tales. Every piece of dirt in grass seem to fly in from blocks away as the unwarned massive dustdevil engulfed the wide open chase van. The devistation left in it's wake was enough to make even strong men weak in the knees....all that work...just....gone. :shock: The entire van was full of dirt and grass plastered to the fresh armor all.

This had a profound effect on me and even now, every time I clean the van, I keep an ever watchful eye out for another unexpected attack of the devil winds. :wink:

:lol: I so remember that! Ohmigawd at the cussing that went on....I was almost on the ground laughing about it and his reaction.

You forgot that dustdevil we saw going to my parents last year...when was that, Thanksgiving? Or was that the 2003 convention? HUGE, making a beeline for the road, looked like a massive wedge. We drove right by it as it was in the pasture with Abbot and Costello....remember?

Didn't make it all the way to the house, though....guess the neighbors' houses took the brunt of it. :shock: