Daily Archives: 27 July 2011

Dust devil chasing lessons

As we’ve all heard on the news, summer 2011 has been hot, hot, hot. Some places in Oklahoma have had high temperatures above 100 oF for over a month, overlapping with areas of exceptional drought.

Needless to say, chase season has been pretty dead down south. The jet stream has shifted north toward Canada, and we’re ridged out. I’ve had to content myself with watching storm videos shot by my northern bretheren. So far, my favorite has been this one from Roger Hill (especially around 2:30 in – wow!).

My husband surveys a potential dust devil breeding ground
My husband surveys a potential dust devil breeding ground
I still hunger for vorticity, however. Fortunately, my husband, in addition to his many other endearing qualities, is a dust devil geek. He studied dust devils as an undergrad at Purdue. The last two weekends, we’ve gone dust devil chasing, and I’m learning that there’s actually a fair amount of skill that goes into it.

Here’s the recipe for dust devils:

  1. Sunshine. The Oklahoma sun has certainly not been in short supply of late! A few clouds are okay, but you want to be in sunshine a majority of the time. Peak daytime heating (which occurs at local noon) is best.
  2. Light winds, < 10 mph. If the winds are too strong, the dust devils will be sheared over and weak. We check the Oklahoma Mesonet wind maps before heading out.
  3. A dry, open field, preferably freshly plowed, and with fine soil particles that are more easily lofted.
  4. Patience. We sit in place for up to an hour at a time in the blistering sun, with very little breeze to offer us relief. With the punishing heat we’ve been experiencing, we also pack ample beverages and sunscreen.

Dust devil crossing OK-37 near Tuttle, OK
Dust devil crossing OK-37 near Tuttle, OK
We still observe the same rules we do when we storm chase – i.e., we park our car completely off the right-of-way, and never trespass on private property. We are accustomed to being approached by people who wonder if we’re having car trouble, including cops. Usually, they are bemused when we explain what we’re up to, and often offer us suggestions for good dust devil viewing spots.

On our last chase, we saw dust devils every 5-10 minutes, usually on the leading edge of microscale gust fronts. As the dust devils passed by us, the breeze would usually kick up, and often, we were passed by dust devils on both sides. Most were short, weak, and transient, but a few (like the one pictured) lasted several minutes, and sent a tower of red dirt over 50 m in the air. Not bad!

Dust devil chasing is relatively easy and safe compared to storm chasing. Dust devils may not be a tornadoes, but they rotate, they’re convective, and unlike a tornado, you can drive or run through one safely (literal “chasing”!). I could easily see dust devil chasing being an educational parent-child activity, particularly if the child has any inkling that they want to chase storms when they get older. They would have to interrogate the surface observations, make a forecast, and navigate to a good viewing spot. They would learn that the best things come to those who wait. And, there would be a much greater likelihood of (repeated) success!