Questions about a funnel and something else???

[Joshua Nall]

I took these photos on April 2nd of this year, the day before the Dallas area tornadoes. I forget exactly where, but it was out west of Fortworth where the storms fired off before dark. I watched this funnel for about 2 minutes till it roped out. First photo is when I first spotted it, the other is soon before it broke up. I was looking West with an updraft south of due west, so this would have been under where the storm started to anvil over I think. I was surprised at the lack of visible rain since there was some falling west of me from the anvil. Would you call this a shear funnel or a funnel in association with the storm? It obviously had no chance of reaching the ground, not in association with the base at all. It was way up there. Are all funnels like this considered “shear” funnels and referred to as such? I’ve also heard them reffered to as midlevel funnels. Is there a difference?

Also, sitting in the same spot I saw this to the north of me under the anvil of the same storm. The look of it made me think it was some sort of down burst descending from the anvil. Maybe an area of more intense rain, but radar at the time showed a very uniform pattern of light rain descending from the anvil. I wish I had timelapse of it or stayed to watch it, but I think I left soon after this. Just wondering if anyone had seen anything like this or knew what caused it.

Close up:

 

[Skip Talbot]

Nice catch, Joshua. I'd probably call that a midlevel funnel. I typically think of shear funnels as small, possibly brief funnels where powerful winds of opposing directions are juxtaposed such as a surging gust front encountering strong inflow, or a powerful RFD where it meets an updraft. Here's one we saw in '09:

In that second image you can see it on the very left side, super tiny. You can see it's right on the edge of the updraft base where it meets the RFD clear slot. The opposing currents there are probably causing a small eddy that's getting stretched by the updraft. With a midlevel funnel you've often got an existing rotating updraft that's being stretched. They become most visible when the surrounding cloud decays around them, while the funnel persists, exposing it so you can see it. There was a great example from July 23 last year in Minnesota. Low topped, minisupercells were getting culled by the cap. As the updrafts shriveled into orphaned anvils, the existing rotation in the updraft tightened up and the result was a funnel protruding from a decaying anvil. Someone posted some great shots of this phenomenon to Facebook, but I can't find them now.

That second shot is definitely caused by either a shaft of rain or virga, locally lowering the level of the cloud base as the rain cooled air becomes saturated. The radar beam is probably hitting above that feature and/or it's too small to be resolved.

 

[Keith Wilson]

Caught this one about a week ago. The nearest and largest one had anti-cyclonic rotation, while the more distant one had cyclonic rotation. The seabreeze collided with strong outflow from a formerly strong line to the north. Neither were located where you would expect to see funnels.

 

[Joshua Nall]

There was a great example from July 23 last year in Minnesota. Low topped, minisupercells were getting culled by the cap. As the updrafts shriveled into orphaned anvils, the existing rotation in the updraft tightened up and the result was a funnel protruding from a decaying anvil. Someone posted some great shots of this phenomenon to Facebook, but I can't find them now.

Thats really interesting. We would probably notice more stuff like this if so much of the time out there were not spent in a vehicle. Thanks for the explanation.