I am looking for photos of full cumuloform pre-tornadic or currently producing

[calvinkaskey]

I am curious if a visual of the cumulus form of later or currently producing tornadic thunderstorms can foretell tornadic activity through shape and texture of the cloud as a whole. For example it seemed like this tornadic supercell was rotating at the top, and exploding linearly from top to bottom with some exceptionally bulging "impulses" This was the best formed supercell at the time in North Carolina under a tornado watch. 15 or so minutes later a fairly long lived tornado (equal to or > 15 min.) and probably the strongest of the day formed (out of maybe a dozen)

 

[Jeff Duda]

Only to a certain degree, and not one specific enough for small scale discrimination. In other words, if the anvil of a storm looks wispy, it indicates a weak or dying updraft, meaning the storm in general is probably either weak or dying. The probability of a tornado in a dying storm is much lower than the probability of a tornado in a healthy, established supercell.

Those are the sort of "convective scale" cues one can use to determine in a broad or general sense if a storm has a decent shot at producing a tornado. On the sub-convective or even tornado scales, I doubt the visual appearance of the cumulus texture of a storm gives any reliable indication of whether a tornado will or will not happen.

 

[Marcus Diaz]

And even a healthy storm won't produce. This storm near Plainview, TX on June 7 of this year had everything going for it. Great instability, decent flow aloft, and hell, it was riding a very pronounced outflow boundary. I was certain it would produce at some point. But it NEVER did!

Then you can have something like this. Right about when I took this photo this storm was producing a strong EF-4 tornado. This was more of a high shear, modest instability day.

You can clearly see the differences in updraft and anvil appearances. Quite a bit of difference.

 

[Warren Faidley]

This is a very interesting topic and something I've wondered about quite often after all these years of photographing storms.

There are two cloud formations that always get my attention: The first are protruding horizontal and / or vertically aligned "ribbed" cumulonimbus as seen in this example: http://www.weatherstock.com/royalty...Royalty Free Pictures/index.html#SC-RF-10.JPG

The second feature are rock-hard appearing mini towers in the updraft region as seen in this picture taken about 10 minutes before the Laverne, OK tornado in 1991.
http://www.stormchaser.com/temporary-file-SC-24.jpg

I assuming the features are more indicative of extreme instability and upward velocities / shear as opposed to some unique feature associated with tornadogenisis.

Now I shall go apply for a research grant and become a scientist!

W.

 

[Rob H]

Overshooting tops and thermal couplets are pre-cursors to tornadogenesis that have been investigated for years by CIMSS, but the former are rather common, and the latter are impossible to discern without a satellite view.

 

[Skip Talbot]

This low topped storm produced a tornado in Kansas on 24 February 2007:

Low topped, mini supercells and cold core convection might give you the best whole storm views. I suspect, however, that different thermodynamics and shear profiles are going to produce highly variable convective structures in the updraft tower, even though a range of these conditions may also support tornadoes. Perhaps there are visual indicators for a particular set of conditions of setup.

 

[calvinkaskey]

Wondering

Was the first storm pic (one on top) taken in a tornado watch area? Is the tornadic storm the nearest one or the one behind it.

And even a healthy storm won't produce. This storm near Plainview, TX on June 7 of this year had everything going for it. Great instability, decent flow aloft, and hell, it was riding a very pronounced outflow boundary. I was certain it would produce at some point. But it NEVER did!

Then you can have something like this. Right about when I took this photo this storm was producing a strong EF-4 tornado. This was more of a high shear, modest instability day.

You can clearly see the differences in updraft and anvil appearances. Quite a bit of difference.

IS THE FIRST STORM MULTICELLULAR AND THE SECOND SINGLE CELLS?

 

[calvinkaskey]

I was trying to edit the above post. I guess seeing something out of the ordinary under a tornado watch or severe thunderstorm watch makes me wonder about the potential for a tornado. The storm in North Carolina had massive bulging rings of convection with lips or curls on the bottom of the rings. The storm in New York that produced an F-3 (maybe closer to F-2) tornado seemed to be more massive or wider than normal. In the bottom picture there seems to be an extension of convection in front of the anvil which I didn't see in the tornadic thunderstorms I was looking at.

Are larger storms more likely to produce a tornado? Are storms that are more symmetrical more likely to produce?

 

[Marcus Diaz]

Calvin, the first picture was the 1 and only storm that day near Plainview, TX under a tornado watch. The next storm was the only tornado producing storm on November 7, 2011; a day with numerous supercells in SW OK/NW TX. The rock hard cauliflower updrafts are more promenant with higher CAPE days. I don't remember what the numbers were for either day but June 7 had way more CAPE than November 7.

 

[Dan Robinson]

Hard-edged convection simply shows that a strong updraft is present, which is usually associated with a greater chance of some type of severe weather being produced. Whether such a storm has tornado potential, however, has more to do with the lower-level wind fields. Hard-edged convection occurs on many non-tornadic days as well.

On a day with surface-based storms and favorable wind fields for tornadoes (clockwise turning with height, backed surface, etc) as a general rule "harder edged" cumulonimbus is a good sign for tornado potential simply because it means stronger updrafts are present. But the cloud-top/side appearance of tornadic storms can and do cycle from "mush" to "hard edges", even on good tornado days. A mushy-looking storm can suddenly change character if the environment begins to change - a weakening cap, increasing LLJ/surface convergence, arrival of cooler temps aloft, etc. 4/32/07 Protection, KS was a good example. The storm initially looked like garbage aloft, but suddenly went crazy at sunset. What the top of the storm looked like at that time I didn't know, since I was under it. Generally if you have a storm in a good environment, you don't judge it by its tops - you judge it by the potential in the given environment, especially if there is a good chance intensification will happen as it matures. You want to be close to the storm if that happens, not far away enough to see the tops.

As Skip pointed out, the low-CAPE high-shear days can often have very weak-looking cumulonimbus, with tornado potential coming largely from near-surface CAPE working with the low-level wind fields.

 

[calvinkaskey]

Looking back at these photos and the videos they came from the top of the thunderstorm seems to have been cleared of convection and or moistened the upper atmosphere more as in the second one the top has "left". Again I think that the "tubing" (bulging) of the thunderstorm around the entire thing might be indicative of severe weather. I'm also noting the peaking of convection around the bulge in the second pic ie. "little" triangle shaped convection around the bottom innertube of convection. Immediately after this convection exploded so rapidly the thunderstorm on the left shows no upward movement of the clouds in comparison.

I'm wondering if I can or should change the thread title to what storms to chase and what ones are not as good. I think we all know what a dying thunderstorm looks like though, so discussion in much more detail and all dealing with developing thunderstorms. With that said the thunderstom I am showing pictures of was the most impressive looking thunderstorm I have ever seen.

This pic is from the NWS when it talks about severe weather. http://www.srh.noaa.gov/images/bmx/Daily/svr/singlecell.jpg. It shows a big bulge in the middle most likely indicating explosive growth. Here is another one that looks exceptionally massive.