Topic: Most Active Parts of Storms for CG lightning activity

[Mike]

I was pondering today and hope that some of you more experienced chasers can help me.  When watching a storm come in, is the highest concentration of lightning strokes likely to be within the rainshaft(s) of the cloud or on the outer regions of the cloud?  I know that it can occur at any place, but i've seen many photos of lightning from within the rain curtain(s) or in the middle of the storm per se?  Also what is stattico lightning - is that just another name for CG lightning with branching?  Is there a particular part of the storm that is more active during its cycle than other parts of it?

Mike

[Jimmy Deguara]

HI Mike,

I think you are on the money here. Rain curtains tend to create a form of discharge and the onset of a rainshaft conincides with a lightning barrage. Of course this is generalised. The best concept to follow is a pattern of what you see on the day. I have found that lightning behaves similarly based on atmospheric conditions.

When you get into some of the well structured storms such as supercells or severe organised squall lines, and in very high CAPE environments, I tend to see occurrence of anvil lightning as well. These can be rather scary as they are eratic and very hard to pinpoint where they will strike or from where!

I hope this gives some insight.

Regards,

Jimmy Deguara

[Mike]

Yes, for sure, Jimmy.

  I think we're all in that area of the unknown.  I would agree that within the rain shaft there would be some sort of additional electrical activity because as we know rain droplets do in fact cause static discharges due to friction during their updraft and downdraft phase, so that could be part of it also. 

As you say, although I have not seen a single supercell in my life (yet!) but have seen discharging from the very top outer tip of an anvil right to the ground around the circumference of the cloud itself - truly one of those things that you thought didn't happen but does!

[Michael Thomas]

Well I'm no expert in this area at all and must say that lightning has always puzzled me. I have noticed that quite well organised storms can sometimes have very little CG lightning where as I have seen some high based multicell storm that are quite lightning active. I think the most dramatic example I have seen of this was in Boulder, Colorado. One day some multicell storms came though and they were very lightning active (someone was killed by lightning unfortunately that day), several days later an organised isolated storm moved though that was severe and I barely saw a cg. Back to the question, I have noticed that alot of cg's can come from behind squall lines, I have only noticed this twice and would be interested to know whether this is common. Also, I think it would be nice to start a thread on lightning in general since it is so interesting, I know I have read of the polarity of CG lightning changing during tornadic storms and smoke from forest fires affecting the lightning activity of storms.

Michael

[Jimmy Deguara]

One important aspect Michael I found are the lapse rates. Steep lapse rates can cause stronger and rapidly developing updrafts and in these cases you can get a barrage of lightning. This was certainly the case in the following event:

http://www.australiasevereweather.com/forum/index.php?topic=225.0

There were episodes of lightning barrages but to me the on that occurred during the 8pm period seem to be very lightning active.

Regards,

Jimmy Deguara

[Mike]

Well Mike i'm all for continuing the topic of lightning.

 I Jimmy is also correct in regards to smoke enhancing lightning because as a good example is volcano eruptions - lightning does occur with the extraordinary upward motion of the plume of ash and smoke from the cone.  So it would make perfect sense to me that any particle - be in water droplets, ash or anything else that can cause friction will cause a discharge.

Those of you who have seen supercells would probably be aghast at the amount of lightning these produce, I can only imagine!.  Yet on the other side of the coin, my mate in Oklahoma has seen huge tornadic supercells with little CG activity - yet others with so many you couldn't count them - yet the processes of formation are the same!

I'd like to know if any of the forum members have seen damage by CGs while they were actually observing - ie - has anyone almost been hit while observing????  I'd like to read of some.

Mike

[Mike]

As an aside gentlemen, what is staccatos lightning?  I've seen the photos and probably taken shots of it myself - but perhaps you could enlighten me!

[Jimmy Deguara]

Staccato lightning are very quick highly branched lightning bolts!

I will try digging some good examples up!

Regards,

Jimmy Deguara

[Michael Thomas]

I agree that steep low/mid level lapse rates are a major factor in many lightning active storms. However, to my knowledge LP supercells are not usually very lightning active and often form in areas with steep lapse rates but limited lower level moisture. In regards to smoke changing the lightning activity of storms, I think their conclusion was that the increased concentration of condensation nuclei affects droplet size and that influences the lightning activity of storms. I can dig up the references if anyones interested.

Michael

[Michael Bath]

I think dry air at a certain level plays a big part, but not really sure what level exactly and it would depend if it's a day of high temps (say mid 30s) and high based cells or warm temps (high 20s) and lower bases. Two recent examples on the Northern Rivers with an extraordinary amount of lightning were 28th Nov 2006 (hot day, high based) and 15th December 2006, very warm day, low bases.  Of course the lack of soundings close to where these storms were observed and near to convection time makes it very hard to know what are good conditions for high CG rates.

MB

[Jimmy Deguara]

Michael,

The following explanation I suggest is pure speculation I guess.

Of course the lack of soundings close to where these storms were observed and near to convection time makes it very hard to know what are good conditions for high CG rates.

Based on behaviour I have observed with storms over the years, lightning behaviour in certain atmospheric profiles tend be fairly similar. So I personally don't think you being close to Brisbane would have much of a difference in the behaviour of the lightning as if you had taken a sounding nearby particularly if there is no reasoning for their to be much of a difference.

When you compared the two cases you mentioned low based case as compared to high based, and you suggested both were lightning active, would you suggest:

- CAPE was resonably high say around the 2000 mark

- lapse rates were steep?

What do others think from their personal experiences?

Regards,

Jimmy Deguara

[Michael Bath]

I mean a Brisbane sounding 8-10 hours prior to storms 200-300km away is not much help in analysis.

CAPE was approaching 2000 in both cases. I have the GFS analysis runs for 06z that can be posted if that is any help.

regards, Michael

[Mike]

Greetings guys (and gals)

Just on lightning again; I have read from forum members when chasing storms that when they see 'anvil crawlers' that they move on to another location.  Now, is it the case that this sometimes is the precursor to the storm dying out?

 I guess that I've seen lots of storms with crawlers but never really took much notice of 'when' it is occurring per se - so after all the CG activity is diminished, is this an indication of the storm becoming spent?

 It seems the more I'm learning from the forum the more I'm observing storms first rather than taking photos and you see 'that' strike or anvil crawler and you think there will be more, but no more appear and you've missed the moment!

cheers.

[Jimmy Deguara]

Hi Mike,

My understanding from experiences in the field is that anvil crawlers occur in a region mostly where the updraft is weakening and becomes elevated. The storm or main updraft may still be severe but the remnant anvil is what may produce the anvil crawlers.

Regards,

Jimmy Deguara

[Mike]

So that would explain why most of the crawlers i've seen have been on the back end of the storm as i'm watching it moving away from me.  ah ha, now i see.  Yes and also that the storm could be still severe or strengthening also - it's just that the storms i've seen of late with this activity may be because i've gotten to observe them late from the back end - as there were no crawlers to the front of the storm/anvil.  I guess it's like when you see the storm coming, you see the rainshaft, the CGs, the gust of wind and once the storm passes you still get the CGs - although diminishing - and then you get a sort of lull in the drama and then there's a whole host of crawlers on the backside of the storm - so that's why i was asking, but yep makes sense to me.