Hopkins County Tornado TV special

[Dan Cook]

Check it out on Youtube. The other parts are on there as well:

http://www.youtube.com/watch?v=dq98NkO8AJs

 

[Danny Neal]

Is there any truth to the "part 1 445-500" That once you see the lightning let up that the tornado is imminent? Should he say once the rain lets up and you get in the hook? Looks like the Lightning actually increases in the vault region of the storm. I could be totally wrong....just an observation

 

[David Drummond]

Most of the time, I have noticed when there is a dramatic increase in CGs that a tornado often pops out very soon. It's not always of course (nothing with storms ever is) but as a general rule, that has been my experience.

 

[Danny Neal]

Most of the time, I have noticed when there is a dramatic increase in CGs that a tornado often pops out very soon. It's not always of course (nothing with storms ever is) but as a general rule, that has been my experience.

I thought so. I have noticed on many tornadic storms the CG's increase. Just wanted to confirm this idea.

 

[Jordan Hartley]

Is there any scientific evidence that supports the theory that tornadoes feed off of conductivity like areas with a high concentration of metal, like mobile home parks and industrial parks, ect?

 

[Jeff Snyder]

No, surface electric conductivity patterns wouldn't affect a tornado. The connection between severe convection and electrodynamics isn't understand entirely well. Some storms exhibit very high flash rates in the times preceding tornadogenesis, while others show the opposite. Heck, we're not even entirely sure why a disproportionate number of severe storms in the western High Plains exhibit an inverted polarity structure (the main pos/neg charge 'reservoirs' are opposite those typically observed in thunderstorms). With electric fields on the order of 300-400 kV/m in parts of some storms, there is the possibility that electric fields in storms may affect updraft intensity to some degree (charged particles -- e.g. raindrops -- experience significant acceleration in the presence of such strong electric fields).

Some storms have shown a significant drop in lightning activity during tornadogenesis, which some have speculated to be the result of the tornado "shorting out" the electric field in the lower part of the storm. In other words, the tornado (more specifically, the condensation funnel, with high liquid water content) may provide a good source to ground through which the source/charge region(s) in the lower part of the storm may drain, neutralizing the low-level electrical field. On the other hand, other studies have shown an increase in lightning activity immediately preceding tornadogenesis, possibly the result of increased charge generation and separation associated with a strengthening updraft. Then again, some storms have main updrafts that have weakened at tornadogenesis (the result of increased rotational kinetic energy?), though, I suspect, the same storms have had increased low-level updrafts associated with convergence along the RFD. This is a large amount of speculation, as we have a lot to learn about electrodynamics and its role in deep moist convection (for example, we're not even entirely sure how lightning initiates to begin with given that observed electric fields in storms are several times weaker than those needed for dielectric breakdown... The latest thinking involves incoming cosmic rays initiation runaway electron avalanches).

 

[Jason A.C. Brock]

The large rain wrapped cone shaped tornado that appeared frpm the massive HP supercell in Knox County near Truscott Texas back in 2005 appeared right after a significant increase in CGs. it was actually quite spooky seeing such a large tornado which was there the entire time and see it appear from the heavy heay rain shaft. While this occured CGs were hitting very close and a new wall cloud ha formed to the SW.

I have seen lightning increase with tornadoes forming as well as areas of intense rotation picking up.

 

[Paul Austin]

The large rain wrapped cone shaped tornado that appeared frpm the massive HP supercell in Knox County near Truscott Texas back in 2005 appeared right after a significant increase in CGs. it was actually quite spooky seeing such a large tornado which was there the entire time and see it appear from the heavy heay rain shaft.

Was this May 13, 2005? If so, are you referring to a time frame prior to the circulation's crossing of the highway? I remember a large chaser convergence and very close CG's driving chasers back into their vehicles. As the meso attempted to reorganize and cross (CR?, SR?) 6, the CG's seemed to taper off somewhat just prior to the storm's dropping this (sorry for the poor quality), which was to the east of the highway. Just curious if this is the same storm and time frame.

Another curiousity: I've often noticed a peculiar quality of non-CG's with some supercells. In storms with rather vigorous updrafts (May 12, Harper Co. among several others), I've often observed cloud-to-cloud lightning bolts that exit the base of the updraft as if to connect with the ground but return to the base in somewhat of a horseshoe shape. I'm not referring to an anvil to lower-level connection. That would not be uncommon at all. Nor are these the typical crawlers. These bolts would often appear to reach beyond halfway to the ground, turn horizontal, and return to the cloud base, with a more instantaneous strike appearance. I probably would never have taken note, except that they seem to come in bunches. Has anyone else notice this phenomenon, or is it just me? I call it, affectionately, "horseshoe lightning".

 

[Jeff Snyder]

Paul,

You mean something like (c. 2006, J. Snyder):

I've seen that other times as well, and I can't really explain it. I'm not entirely sure why it would loop back into the cloud. Also interesting to me -- some strikes have multiple return strokes (strobe-light effect), while others seemingly have no return strokes. While chasing a supercell on an April chase in sw MO last year, Gabe and I witnessed a myriad of CGs, most of which were extremely bright and had no multiple return strokes. On other chases, I've seen storms which contained many CGs that strobed several times (numerous return strokes). Now, I know positive CGs tend not to have multiple return strokes, so perhaps the multiple-vs-single return stroke strikes are usually determined by the polarity of the strike. Then, there's the whole "highly stepped" vs. "pseudo-linear" deal... Some CGs seem to be quite linear, going straight from cloudbase to ground (--------), while others are highly tortuous, with many changes in direction (/\/\/\/\/\/\/\/\\/\/\).

FWIW, and slightly related, mapping arrays have observed that some lightning bolts extend for 100-150km horizontally in the cloud. So, next time you see a CG in an MCS, there's a chance that you're only seeing a very, very tiny part of it.