| Lamar-Plant City |
| (Storm Tracker) |
| Fri May 04 2007 02:01 AM |
|
Very large whirlwind/dust devil....
|
Maybe this isn't significant, but in my 43 years, I have never seen anything quite like it. Yesterday (May2) at about 5:30pm as I was coming home from work here in Plant City (east of Tampa), I saw the largest, most impressive and most persistent dust devil I have ever seen. At first glance it REALLY looke like a tornado. What was impressive is that it was constructed like a tornado and was at least 5 miles away from me. I drove toward it for about 10 minutes (in traffic), watching it slowly move from north to south just to be sure I wasn't seeing things (I had NOT had anything to drink...honest:). It was then that I realized that it must have reached a height of 500-1000 feet as its top looked very close to the flattened thin cloud cover over central Florida that day. It slowly faded and dissipated but was an impressive sight. Has anyone ever seen something like this? Most dust devils I have seen before were short-lived and rarely seemed to extend upward more than a hundred feet or so. I HAVE seen one rip the roof off of a mobile home from within 50 feet before, so I know they can pack a punch. I have seen no news reports on it, but it was over a relatively sparse area east of town. Conditions were....hot (at least 90), not a lot of wind overall, with flattened cumulus that didn't look more than about 2000 feet to the bottom, with lots of haze from fires to the north. Am I crazy? Thanks for your input!
Ed Dunham
|
| (Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)) |
| Fri May 04 2007 03:15 AM |
Re: Very large whirlwind/dust devil....
|
The size of the dust devil that you observed is a bit uncommon for Florida, but not in places like west Texas and Arizona. I've seen them reach 5kft in height with winds up to 70mph in Arizona.
ED
| Lamar-Plant City |
| (Storm Tracker) |
| Fri May 04 2007 04:25 AM |
|
|
|
Re: Very large whirlwind/dust devil....
|
Thanks for the input....it could have been taller than even I thought....it was one LONG whirlwind. I really had to look to make sure it wasn't a real tornado it was so distinct. One of the few times I wish I had a phone with camera on it.....hmmmmm
| Lamar-Plant City |
| (Storm Tracker) |
| Sat May 05 2007 01:38 AM |
|
|
|
Re: Very large whirlwind/dust devil....
|
Talked to someone else tonight who witnessed the same thing, so now I am sure I didn't dream it....he tried to get a picture with his phone-cam but said it didn't come out good enough.....
| HanKFranK |
| (User) |
| Tue May 08 2007 04:08 AM |
|
|
Re: Very large whirlwind/dust devil....
|
dang, where's a camera when ya need one? i've never seen one that big this far east. not even close--just a couple dozen feet high of dust in an updraft is the extent of it. this IS the time of year to see 'em... atmosphere isn't nearly as warm aloft as it will be later, and surface heating is very strong.
i've got a fuzzy pic of one with me in the foreground, in the breakdown lane of i-10 east of van horn, tx with a tall plume of dust off in the distance. it doesn't seem that impressive until you see the tiny house, a speck nearly a mile away, with the dust devil off beyond that. that thing was at least a couple thousand feet tall...
i keep thinking i want see a tornado up close, too, but after one blew my old high school away in march i've decided ONLY on my terms.
| cieldumort |
| (Moderator) |
| Sat Jun 09 2007 05:26 AM |
|
|
Re: Very large whirlwind/dust devil....
|
Speaking of which - and this may be of particular interest to those of you in Florida who witness any future -especially tall- dust devils.. While living in Arizona I witnessed at least one occasion of a true dust devil to landspout transition.
This started out as a bona fide dust devil, although a particularly powerful one which reached higher and higher into the sky, and finally happened a meet-up with a towering cumulus not perfectly overhead, but which eventually drifted just about directly overhead. Anyone who has chased tornadoes before observing this -after- the transition would have assumed it was a classic landspout. Someone else observing this from the start, but not from the excellent vantage point I had, may have easily mistaken it for nothing more than a dust devil. I had the benefit of being up on a hill looking down at the base of the dust devil from not terribly far away., and with little or no obstructions from surface to cloud base.
It was a fantastic occurrence. Truly rare. F0, by the way. Made the evening news.
| madmumbler |
| (Storm Tracker) |
| Sat Jun 09 2007 01:15 PM |
|
|
Re: Very large whirlwind/dust devil....
|
So what's the difference between a true tornado and a dust devil?
| cieldumort |
| (Moderator) |
| Sat Jun 09 2007 04:58 PM |
|
|
|
Re: Very large whirlwind/dust devil....
|
A dust devil is never a "true tornado," in and of itself, and without any special extenuating circumstances, as existed at that exact moment I was so very fortunate to witness.
A tornado by very definition is a violently rotating column of air in contact with the ground and generally pendant from deep, moist convection. In other words, you need a "deep" cumulus-type of cloud. This is often cumulonimbus - (a thunderstorm-) or frequently in Florida simply a towering cumulus over water. AND you need a violently rotating column of air spinning between it and the ground, or water. Waterspouts ARE very simply simply tornadoes ...over water, and are usually NSTs (Non-Supercell Tornadoes) ie: classic "waterspouts." In much the same way a waterspout develops, so do "landspouts." - I'm digressing to add more background to the question you did ask:
Dust Devil: Rotating - but rarely "violently rotating" - updraft usually found on cloudless days - or at least most usually NOT directly under, or influenced by, deep moist convection. These are most common on clear, hot summer days with otherwise gentle ambient winds, but with uneven surface heating. There is deep convection going on, but nothing related to deep, "moist" convection.
NST (Non-Supercell Tornado): Rotating column of air - often "violently rotating" - that forms as preexisting, but rather diffuse or otherwise rather benign spins or shears in the lowest 100 mb or so of the atmosphere, are drawn into the updraft of a cumuliform cloud, tilted much more into the vertical, and then stretched. This stretching results in the broad area of shear or rotation picking up speed and become far more focused (Think of the proverbial ice skater pulling in his/her arms).
NSTs are most of what you see in Florida, especially over water. They are also very common in northeastern Colorado.
Conversely, a tornado born from a supercell thunderstorm is associated with many very similar, but fundamentally different processes, having much more to do with the cyclogenesis of the parent thunderstorm (mesocyclone, etc.)
Roger Hill (Silver Lining Tours), has some impressive footage of landspouts on their homepage.
For visual and descriptive comparison, here's a great page on dust devils from a JC in Maricopa County, Arizona.