Thunder Watch

[Dean.]

A nasty hail squall that fell in a narrow strip.

[NZ Thunderstorm Soc]

Just come back from observing this afternoons thunder activity from around the Rolleston area. I had problems with my video camera so not much recorded except for some cloud shots.
The darker skies to the north of ChCh around 2pm interest me much as it was heading away from us and was what Jim Hickey would describe as a 'Gone-burger" and I was certain that more development would be occuring to the west of here.
I had a report of a thunderstorm at Methven at 2:30pm with 1cm hail falling, so went an investigated but never ventured too far away as it didn't look very good from despite what was accually happening in the storm. I was hoping the Deano may of gone and investigated and I'm glad he did. You'll have to be Ashburton rep of the NZTS. I never saw any lightning though but from my position I heard lots of rumbles so much of the lightning was in the cloud.
Then about 5:30pm it quickly dropped away although it spread a veil of glaciating cloud and mammatus proturerances out towards ChCh/BP with light rain falling. I don't know whether it was a 'heat' related thunderstorm as it hasn't been really all that warm and there has been a cool Ne blowing in ChCh this afternoon.
Deano, thanks for the photos and the reports.


JohnGaul
NZTS

[tich]

I don't know whether it was a 'heat' related thunderstorm as it hasn't been really all that warm and there has been a cool Ne blowing in ChCh this afternoon.

The sun still should've heated the ground enough - I think it was warmer in inland Canterbury than in Chch (without the cooling NE sea-breeze). Plus we've been in an unstable airmass - ideal ingredients for thunder and hail development. Looks like it's all over now - just scattered thin high cloud.

[NZstorm]

I would say thermal heating and perhaps some convergence were the trigger action. Air looked fairly unstable with a lowish freezing level, so not particularly high temperatures needed for cloud buildups. Central Otago missed out on the showers/storms because the air was a bit to dry I would say and by the afternoon the more unstable air was departing that area.

Deano's photos were interesting.

Should be some more unstable weather by Sunday or Monday.

[Thunder]

What a cool day! Managed to duck out and take some pics but they don't seem to capture what it was really like. Some of the cloud builups during the day looked really good due to the way the sun shined on them, as Ben (tich) said, they looked spectacular!

I woke to a fine and sunny morning and quickly ran for the bus about 7:15am and when the bus turned a corner not to far down the road I looked to my left and saw massive big Cu clouds to the east (they were huge!), one had gone to a Cb and they looked really awsome! this due once again as to how the sun shined on them. I couldn't get any pics unfortunately, odd considering it was early morning but these buildups were most definately there, did anyone else see them?

I guess from about midday things began to look interesting again, the following pictures are taken from Wigram. I actually didn't see any lightning at all during the day but I think I heared thunder on one or two occations, I was allways hopefull a tornado would pop out of one of the Cb's but of course nothing happened.



Front and side of big Cb in the distance, sorry pic is on bit of angle.



Back of Cb as it goes in an ENE direction.



Front anvil of one of the Cb's during the day.



This Cb looked huge! Almost supercellish, but I could'nt really tell from where I was. That bit of darkish cloud in the foreground of the picture annoys me a little as it obscures the front anvil of that big Cb.



Back of Cb with anvil up high and what looks like some type of inflow (updraft?) structure feeding into the Cb.



Big Cb in background, sorry about the low lighting! My pathetic little digi!



Lots of big Cu. Wigram airport is big green area.



Underneath of Cb, interesting base feature, it later seperated from the main structure of the cloud though and the whole cloud dissapated as it moved offshore (I think it did?).

There you go, not my best work by any means.

I was talking to a guy today and I crossed the topic of thunderstorms etc and he said that when that big thunderstorm came across last Oct on the 27th he saw the tornado come down from it as he was driving along Wainoni road (east side of Chch). He also goes mountain biking along the port hills alot and said that he's atleast twice seen torando type forms, these were on the Banks Peninsula side and not the Chch city side. It made me relise that tornadoes might occur more often than one might think, obviously not like in Oz or the US but I mean it's not like a once in a 10 or 15 year event in Canterbury, mayby one might occur ever two years at the max somewhere in Cantab. Anyway, I'll be on the lookout that's for sure!

Cool Pics Dean! Nice dark base When you say that you might of got some lightning shots on camera do you mean the SLR or automatic 35mm film type format or do you mean with your hanycam? if you did, what do they look like?

Thats not good about the handycam John, these storms definately had some convergence in there I think because I see people from Chch on this forum say that the breeze was E when I could clearly see the clouds moving in a W direction, heat would've also contributed as Steven W says.

Cheers
Aaron Wilkinson

[NZstorm]

Isolated thunderstorms with large hail likely in Canterbury Sunday.
Aaron, take a hard hat with you.

[Thunder]

Will do Steven although I only have a bicycle helmet handy, lol. I've got a hard hat at work but won't be doing that on Sunday! (work that is).

Might I also note that when looking over that AVN forecasting program about conditions for these recent thunderstorms it suggests nothing that would make one think a thunderstorm could happen (in Cantab anyway), so your right Steven, continental forecasting would be easier and NZ weather is harder to predict.

Also on my last post I said I could clearly see the clouds moving in a Westerly direction, woops! I meant the were clearly moving in from the west or in other words they were moving in an easterly type direction. Hope that clears that up.

Ready for tomorrow John? Dean? Anyone else in Chch? Looks like Auckland will be in for some thunder tomorrow too by the forecasts.

Cheers
Aaron Wilkinson

[NZ Thunderstorm Soc]

Ready for tomorrow John? Dean? Anyone else in Chch? Looks like Auckland will be in for some thunder tomorrow too by the forecasts.

Cheers
Aaron Wilkinson

No I won't be available tomorrow


JohnGaul
NZTS

[Michael]

Looks like Auckland will be in for some thunder tomorrow too by the forecasts.

Cheers
Aaron Wilkinson

Are you surprised!

[TonyT]

Looking good for inland storms for Canty for Monday, and possibly convergence type storms on the Plains on Tuesday.

[NZstorm]

The secret to thunderstorm development in Canterbury is the onshore surface wind (NE, seabreeze)

Plenty of static on am band here as isolated thunderstorms move across North Island this morning. Already been a heavy shower in Auckland this morning. Freash westerly, temp 17C.

Aaron, I would'nt advise you chase thunderstorms on your scooter in rural Canterbury. Should never forget that thunderstorms can produce dangerous lightning. Treat all storms as hazardous because people can be struck by lightning. Just a reminder.

Cars are regarded as generally safe in an electrical storm.

[Manukau heads obs]

we had a good squall line with heavy rain go through here 30 minutes ago now...

[Chris Raine]

Noticed your comments re Canterbury Thunderstorms on Friday. We had a number of Thunderstorms to North and Northeast of Invercargill from about 3-5pm on Friday as well. They were forecasted too. Again did not seem that warm so must have been some instability aloft.

[Manukau heads obs]

auckland must be getting this now!

[Michael]

Its currently is black as the Jack of Clubs to the west

[Thunder]

Don't worry I'm not going to chase any thunderstorms on my little scooter thing any time soon, hehe.

Unfortunately Micheal I'm not surprised that Aucklands getting more thunderstorms, lucky people! But Canterburys situation looks good to.

Looks like a Cb could of come over into pegasus bay last night as the radar below and sat pic show at 1:00am.



Hope something happens today or what might now be later on this evening here in Chch. Was NE not long ago with NW blowing up high as could be seen by the cloud direction but now looks to be blowing NW at sea level to. Cb's are currently up and down the alps.

Awsome Pic Brian. It's now saved in my drive! Hope thats Ok.

Cheers
Aaron Wilkinson

[Manukau heads obs]

the cb was so big i had no chance of getting it into the camera area...i just got the edge of it!
it was quite awe inspiring, and very black, as it was blocking out the sun

[TonyT]

The secret to thunderstorm development in Canterbury is the onshore surface wind (NE, seabreeze).

Which is why it wont happen today, might happen tomorrow, and is most likely on Tuesday. There are other factors involved too.

[Manukau heads obs]

ok, ground reports:
that cb i took a photo of hit the top of the peninsular, at big bay, with hail the size of M&M's
south auckland to bombay should have been in the firing line

[Dean.]

Fine and warm in Ashburton now,with a light northwesterly,temp 23 degrees.
Some Cu cloud drifting over Methven way.
As Tony said,not looking likely today,but have the camera charged and ready just in case.
Cheers.

[NZstorm]

Nice cb photo Brian. Interesting to get the hail report.



cb developing over Hunua, east Auckland this morning.

Upper air has stabilised this afternoon. LI -1 at midday but I'm sure it
must be + now.

[Dean.]

Wind has changed here to WSW,temperature is dropping with the wind change.Interesting looking cloud build ups to the south,will go for a closer look.
Later.

[Dean.]

Be on alert John and Aaron,there is a massive CB heading up the Canterbury coastline towards Banks Peninsula,I caught the edge of it at Longbeach which is 30 km south of Ashburton.Saw some great bolt lightning out to sea and also thunder and heavy hail.
The wind is now blowing strongly from the south on the coast,seems to be a convergence with the NW that is inland?.
Photos to follow.

[Dean.]

Hail at Longbeach,4.30 Sunday.

[Dean.]

Photo of CB off the Mid Canterbury coastline,taken about 5.15.