Anti cyclonic tornados

[Joe Filakovsky]

I have heard of instances where these occur in the northern hemisphere. With the exception of the clockwise rotation, can they develop, strengthen and die like a storm rotating counterclockwise?

R/Joe

 

[rdale]

No, they are typically from left moving splits. They are rarely as strong as their normal partners.

 

[mikedeason]

It should be pointed out that while anticyclonic tornadoes are typically weak and short lived, several have been documented as F3 (Grand Island, NE, 1980) and F4 (West Bend, WI, 1981) on the old Fujita scale. Not sure if any have been rated that high on the enhanced Fujita scale.

 

[ahaberlie]

Dr. Wakimoto did research regarding the strongest ever anti-cyclonic tornado surveyed at the time (I assume it still holds this title) that hit West Bend, WI ( mikedeason mentioned it in his post.) I'm not sure if we can post links to journal papers or not but google is your friend.

It was atypical in many ways and wasn't associated with a discrete cell hook echo or an overly strong bow echo signature.

What Wakimoto suggested, if I understood correctly, was that the brief but extremely strong tornado formed on the (south) side of a strong downdraft associated with the dissipation of the bow echo system. From what I've read these are usually called mesovortices if you want to read more about them. This situation, the anti-cyclonic spin and strength, is as rare as it gets.

 

[Joe Filakovsky]

Thanks all....definitely gonna read further

Joe

 

[Mark Blue]

It should be pointed out that while anticyclonic tornadoes are typically weak and short lived, several have been documented as F3 (Grand Island, NE, 1980) and F4 (West Bend, WI, 1981) on the old Fujita scale. Not sure if any have been rated that high on the enhanced Fujita scale.

Mike beat me to posting about the Grand Island event of June 3rd, 1980, and the anticyclonic F3 that occurred that evening. Here's a link where this was discussed at an earlier time when we had a historic sub-forum here. If you comb through the thread there are links to other sources of information, so it's an interesting read. It's by no means a scientific study of the event, but more about recollections and write ups about what happened. I was lucky enough to drive through there the morning after when I was 18 years old, so it's pretty near and dear to my heart and I'll never forget those memories.

 

[Shane Adams]

I've only seen one anticyclonic tornado in 15+ years of chasing. It formed from a "figure 8" type circulation, with the anticyclonic side being just south and west of the "normal" cyclonic couplet. The tornado itself was very weak, and appeared as a concentrated dust bowl below the rotating base. It lasted a few minutes then gradually weakened to nothing. As it did, the cyclonic couplet began to intensify, and produced a 14-minute tornado. This happened near Kiowa, KS on May 12, 2004. Although many saw the "Sharon" tornado (as it's widely-known), our group was the only one to report observing the anticyclonic tornado that preceded it by a few minutes. I'm assuming since our vantage point was different than most I've seen, it simply wasn't visible to most.

 

[Jeff Snyder]

Anticyclonic areas of rotation are not uncommon to the south of a strong RFD surge. As the clear slot advances around the primary low-level mesocyclone, you may see that, on the other side of the clear slot (often to the south for "normal" central US supercell configurations), there exists some anticyclonic rotation. Anticyclonic tornadoes have been documented in this general "area". For example, there was a beautiful example on 4/24/2006 in El Reno, OK:

This was taken near the end of the cyclonic tornado's rope out (on the very far right part of the image). The anticyclonic tornado on the 5/29/04 Geary, OK, supercell was in a similar area (storm-relative), though that was a huge HP.

Anticyclonic tornadoes can also occur in anticyclonic supercells in the much the same way as cyclonic tornadoes in cyclonic supercells. For various reasons (though primarily because low-level warm air advection is associated with a veering vertical wind profile that often tends to preferentially support cyclonic supercells over anticyclonic supercells), these are much more rare events. There was such a tornado and supercell on 5/10/10 in south-central Oklahoma. In addition, Bunkers and Stopkotte (2007) document such an event that occurred in the northern Plains: http://www.ejssm.org/ojs/index.php/ejssm/article/view/14/17

 

[Greg Stumpf]

Anticyclonic tornadoes can also occur in anticyclonic supercells in the much the same way as cyclonic tornadoes in cyclonic supercells. For various reasons (though primarily because low-level warm air advection is associated with a veering vertical wind profile that often tends to preferentially support cyclonic supercells over anticyclonic supercells), these are much more rare events. There was such a tornado and supercell on 5/10/10 in south-central Oklahoma.

And that left-moving tornadic supercell produced a cyclonic tornado in the same fashion that right-moving supercells sometimes produce anticyclonic members (like El Reno). A remarkably rare occurrence!

 

[Jeff Duda]

I learned through a direct hit that you need to beware of anticyclonic spin-ups along the southern edge of the RFD gust front. While chasing with TWISTEX on May 29, 2008, two of the mesonet vehicles were struck by a very small, but also weak, anticyclonic tornado that occurred more than 5 miles southwest of the main supercell tornado (the Tipton/Beloit/Glen Elder storm). I've seen similar occurrences of strong anticyclonic rotation on the south end of an RFD cut before. The circulations never last long, though.

 

[Skip Talbot]

Good point, Jeff. We had a similar incident on June 17 last year in soutbhern MN. From my vantage point, there were several anticyclonic funnels visible well south of the main tornado. Adam Lucio, safely southwest of the main tornado, was directly under these features and reported strong blasts of wind. While it might have just been RFD, its likely he was in a weak anticyclonic tornado:

 

[Jeff Duda]

In my account of the June 17, 2009 chase day, I mention the occurrence of a few anticyclonic supercells in Nebraska. I'm waiting to receive the archived radar data to make some loops, but you can get a peak at what I'm talking about by looking at the end of my chase account here.

 

[Jerry Funfsinn]

This is an intriguing subject on the frequency/occurence of anti-cyclonic tornadoes. I have often wondered if they are not as rare as we might believe. Some examples I have are these two videos. The first is from March 28, 2007 in Edson Kansas. You should note that the clouds in the foreground are rotating cyclonically but the background clouds are rotating anti-cyclonically. You can't really tell the direction the tornado is rotating until it disipates.

Watch video >

The second is from Protection Kansas April 23, 2007. While I was filming this tornado, two more were forming to my west which I did not realize. This one was a satellite and was the farthest east of the strongest tornado that formed with this supercell. The DOW was sampling this storm but I've never found any radar archives from this event. Although I do remember 3 separate mesocyclone with this cell.

Watch video >

One thing I always keep in mind when encountering strong/violent tornadoes is an anti-cyclonic counterpart. H. Bluestein has some great radar images of an anti-cyclonic tornado from the Grand Island, NE tornado of 1983 that can be found here.

 

[Alvaro ivan]

This same incident happens again at june 4 2015 a dusty tornado was anticyclonic in simla colorado