John Farley
Supporter
I am wondering what experiences others have had on chases involving bow-echo tornadoes. True bow-echo tornadoes (not gustnadoes) usually occur when surging bow echoes in an environment with strong shear encounter a pre-existing boundary or outflow from another nearby storm. Usually they occur at or north of the apex of the bow echo.
Research has found that up to 40% of tornadoes in Illinois and Indiana occur in this type of situation, though nationally the figure is about half that. Still a non-trivial number, though.
I have encountered these during chases three times, all in Illinois, and each time by accident after observing earlier supercell activity in the same general area area. One time, the most recent (June 13 of this year near Bunker Hill, IL), I missed the tornadoes as I was more interested in avoiding getting overrun by the bow ceho. [I did see the tail end of a brief tornado under the flanking line of the supercell that occurred a little earlier near Brighton, but the bow echo produced FOUR confirmed tornadoes in and north and east of Brighton, all of which I missed.]
On July 5 of last year, I did see a brief tornado just east of my home town of Edwardsville, though I got no picture because it was ver brief and I at first mistook it for a scud finger. And on July 27, 1997, I encountered and photographed such a tornado in the Quad Cities area (chase report at http://www.siue.edu/~jfarley/chase727.htm ). This looks a little like a gustnado, but there was strong rotation in the clouds as well as on the ground, and the tornado persisted for about 5 minutes.
Each time, I was caught by surprise, not expecting a tornado in an outflow-dominant storm. Yet, in reading about this recently, each case fit the pattern described above which is typical of bow-echo tornadoes. This makes me wonder whether, if one consciously placed oneself ahead of and to the north of the apex of a bow echo, one would have a decent chance of seeing tornadoes. This would, of course, be difficult due to the typical very fast movement of the bow echo.
In my experience, each time I have encountered this phenomenon, the following conditions have been present:
1. There were supercells in the area, which either evolved into bow echo storms or were overtaken by bow echo storms that developed nearby.
2. The tornado occurred in the typical portion of the bow echo, i.e. a little north of the apex (but not in the comma head).
3. They occurred as the bow echo surged forward very quickly and seems to have also encountered a boundary, as described above.
Anyone else have experience with this? What do you think about the possibility of intentionally positioning oneself to see tornadoes in this situation?
Research has found that up to 40% of tornadoes in Illinois and Indiana occur in this type of situation, though nationally the figure is about half that. Still a non-trivial number, though.
I have encountered these during chases three times, all in Illinois, and each time by accident after observing earlier supercell activity in the same general area area. One time, the most recent (June 13 of this year near Bunker Hill, IL), I missed the tornadoes as I was more interested in avoiding getting overrun by the bow ceho. [I did see the tail end of a brief tornado under the flanking line of the supercell that occurred a little earlier near Brighton, but the bow echo produced FOUR confirmed tornadoes in and north and east of Brighton, all of which I missed.]
On July 5 of last year, I did see a brief tornado just east of my home town of Edwardsville, though I got no picture because it was ver brief and I at first mistook it for a scud finger. And on July 27, 1997, I encountered and photographed such a tornado in the Quad Cities area (chase report at http://www.siue.edu/~jfarley/chase727.htm ). This looks a little like a gustnado, but there was strong rotation in the clouds as well as on the ground, and the tornado persisted for about 5 minutes.
Each time, I was caught by surprise, not expecting a tornado in an outflow-dominant storm. Yet, in reading about this recently, each case fit the pattern described above which is typical of bow-echo tornadoes. This makes me wonder whether, if one consciously placed oneself ahead of and to the north of the apex of a bow echo, one would have a decent chance of seeing tornadoes. This would, of course, be difficult due to the typical very fast movement of the bow echo.
In my experience, each time I have encountered this phenomenon, the following conditions have been present:
1. There were supercells in the area, which either evolved into bow echo storms or were overtaken by bow echo storms that developed nearby.
2. The tornado occurred in the typical portion of the bow echo, i.e. a little north of the apex (but not in the comma head).
3. They occurred as the bow echo surged forward very quickly and seems to have also encountered a boundary, as described above.
Anyone else have experience with this? What do you think about the possibility of intentionally positioning oneself to see tornadoes in this situation?
