Timing and Thunderstorms

03Stormchaser · Unread post by **03Stormchaser** » Mon 27/09/2004 15:30

tich wrote:
Heavy rain in chch with some decent looking clouds now closing in
Not heavy, but there certainly has been some rain in the central city. The wind has gone south and the temperature predictably has dropped.

Tich we had a Heavy shower out here in Northlands!! Also a nice build up building up over/behind (its hard too tell) Bp

Manukau heads obs · Mon 27/09/2004 15:30

i see the lightniing detector has pinpointed some along the otago coastline....! ?
http://www.templeton.gen.nz/weather/lightning.htm

dogmelon · Unread post by **dogmelon** » Mon 27/09/2004 15:35

The much fabled timing issue turned out to be a bit of a fizzer today.

Thunder · Unread post by **Thunder** » Mon 27/09/2004 15:45

The first lot of Cu congestus / (Cb?) has moved offshore now and looks like it's all downdraft so nothing more to see there. There is however some nice Cu towers to the SW by the looks of things, hopefully something is in store for us yet. Or maybe it'll be plains only.

The 3pm radar show the heavy rain / hail (probably only small stuff) out at sea which I have some pictures of that I'll put up later.

http://www.metvuw.com/radar/radar-big.c ... 0Z_cny.gif

Yes I see thse strikes along the coast there Brian, wish they were here! Or about 1 to 2 km infront of me would do nicely, lol.

Thunder · Unread post by **Thunder** » Mon 27/09/2004 17:57

Oh well, that's if for today. Perhaps dewpoint a bit too low at 6 / 7C before the change. Considering things maybe it was lucky we got a Cb at all, WNW before a S change isn't the best situation.

Windy now with it being overcast, still a bit of Cu over B'sP but that wont go anywhere by the looks of things.

Lets have a look at one of those pictures again. One is the original shot and the other I've played with the tones and contrast to make it more visable.

03Stormchaser · Unread post by **03Stormchaser** » Mon 27/09/2004 17:59

winds peaked here in CHCH at around 3pm at 80 kph!

Around 3pm ish i saw an anvil forming above bp (again its hard to work out were it was above) looked quite impressive, but then crappy low cloud came in!!

Nice pic! aaron I would say that was a F/C

Thunder · Unread post by **Thunder** » Mon 27/09/2004 18:06

If you look at the link / file name of that comparison shot in my post above you'll see that I still have my reservations. Looks interesting though. When I saw it, it definately wasn't hard to see. I thought, "What's that?".

03Stormchaser · Unread post by **03Stormchaser** » Mon 27/09/2004 18:10

Aaron J Wilkinson wrote:If you look at the link / file name of that comparison shot in my post above you'll see that I still have my reservations. Looks interesting though. When I saw it, it definately wasn't hard to see. I thought, "What's that?".

aaron have some faith

NZ Thunderstorm Soc · Mon 27/09/2004 18:43

Yeah, well actually I went and had a lie down and fell asleep when the southerly front finally came across

No Ne ingredient despite the lovely glaciations in the cloud that brought the areas of rain to Chch, (see 3pm Rakaia Radar)
Nothing much here only a trace or so in my rain-gauge.
On a brighter side, it should be nice and sleety here in Christchurch tomorrow

Roll on the next opportunity for thunderstorms in Canterbury

JohnGaul
NZTS

NZstorm · Unread post by **NZstorm** » Mon 27/09/2004 19:16

How often do thunderstorms originate from heat lows in New Zealand?

Heat lows are localised surface features but they do add to instability through the increased thermal forcing. However, often the real culprit for any afternoon convection would be a weather feature thats cools the upper atmosphere such as a trough, upper cold pool or divergence.

The thunderstorm you refer to was caused by a low coming in off the north Tasman Sea. Auckland recorded 24C with thunderstorms also.

Report here with weather map for that day.
http://www.thunderstorm.co.nz/26%20Nove ... %20%20.htm

tich · Unread post by **tich** » Mon 27/09/2004 19:54

Not heavy, but there certainly has been some rain in the central city. The wind has gone south and the temperature predictably has dropped.

Tich we had a Heavy shower out here in Northlands!

winds peaked here in CHCH at around 3pm at 80 kph!

Chch seems to be a big enough city so that some parts may get certain weather when other parts don't. (like Auckland) It didn't feel like 80 kph in the central city, but there must've been big gusts elsewhere.

NZstorm · Unread post by **NZstorm** » Mon 27/09/2004 20:06

The much fabled timing issue turned out to be a bit of a fizzer today.

Timing is can be an important factor in thunderstorm development, not just in Canterbury but elsewhere in NZ. Most of summer storms are triggered by thermals from daytime heating as well as the resultant sea breezes. So for thunderstorm development you need an area of clear weather within a trough, to be crossing land during the afternoon hours.

As far as today goes, too early in the year. November onwards for the possibility of summer thunderstorms.

jeffsweather · Unread post by **jeffsweather** » Mon 27/09/2004 20:11

tich wrote: Chch seems to be a big enough city so that some parts may get certain weather when other parts don't. (like Auckland) It didn't feel like 80 kph in the central city, but there must've been big gusts elsewhere.

Nor'wester is a lot more gusty at work then it is here. The southerly was gusting to 46km/h here today, nothing out of the ordinary for a southerly change here. Max gust I've recorded this year is was a southerly at 64km/h on the 6th June between 6:10pm and 6:20pm.

The maximum gust I have ever recorded was another southerly at 76km/h on the 5th June 2002 between 7:10pm and 7:20pm.
Still waiting for 80km/h+ winds here.

Manukau heads obs · Mon 27/09/2004 20:14

http://www.davidbuckley.name/weather/

for oxford weather details if anyone wants to know...

Michael · Unread post by **Michael** » Mon 27/09/2004 20:16

max gust 24.3 not high.We had 50+ all last week and 74 or so last week

Thunder · Unread post by **Thunder** » Mon 27/09/2004 20:29

Thanks very much Brian. Good to have an inland (Northish) Canterbury AWS. Are there any others apart from Steven G in Templeton and the Chch airport AWS?

And how often does the Oxford one update?

Manukau heads obs · Mon 27/09/2004 20:35

http://homepages.paradise.net.nz/tmcgav ... ather.html

03Stormchaser · Unread post by **03Stormchaser** » Mon 27/09/2004 21:48

that wind data is from ChCh airport

NZ Thunderstorm Soc · Mon 27/09/2004 22:10

I wasn't impressed with today's weather scenario.

It did get windy here but nothing exceptional. The glaciations in the cloud did look mighty, apart from those mentioned on the forum, I didn't here of any reports of hail/heavy showers.
I saw cloud like the one that Aaron photographed out to the west across the plains whilst biking home form work, prior to the wind change,
Looked like nothing to get excited about as there was no development
According to ECMWF, Thursday looks quite good

....this depending of course of ..... timing

JohnGaul
NZTS

03Stormchaser · Unread post by **03Stormchaser** » Mon 27/09/2004 22:14

NZ Thunderstorm Soc wrote:I wasn't impressed with today's weather scenario.
It did get windy here but nothing exceptional. The glaciations in the cloud did look mighty, apart from those mentioned on the forum, I didn't here of any reports of hail/heavy showers.
I saw cloud like the one that Aaron photographed out to the west across the plains whilst biking home form work, prior to the wind change,
Looked like nothing to get excited about as there was no development
According to ECMWF, Thursday looks quite good
....this depending of course of ..... timing

JohnGaul
NZTS

Youre so modest John

03Stormchaser · Unread post by **03Stormchaser** » Mon 27/09/2004 22:21

NZstorm wrote:Some Canterbury thunder data here

average days of thunder per year.

Timaru 2.8
Fairlie 3.9
Peel forest 5.9
Ashburton 3.6
Rangiora 3.5
Christchurch airport 2.2
Christchurch city 1.5
Banks Peninsula 4.7

This info can be taken as a rough guide only. It relies on the weather observer recording a thunder event. Actual frequencies are likely to be higher. But the Christchurch airport figures are representative because the airport has an hourly observation programme 24/7. Less likely they would miss an occurance.

And with all these locations, Most of the thunder was recorded in the months November to January.

Steven have you got the thunderstorm data for the west coast??

NZ Thunderstorm Soc · Mon 27/09/2004 22:26

03 Stormchaser wrote:
Youre so modest John

Thankyou Steve

JohnGaul
NZTS
Why did the lightning strike cross the road?

NZ Thunderstorm Soc · Mon 27/09/2004 22:48

I'm picking up distant sfrerix

..according to the Templeton Lightning recorder, way out in the Tasman sea off the West coast

JohnGaul
NZTS

Manukau heads obs · Mon 27/09/2004 22:54

hey, its picking up lots of strikes
the sat image confirms an active frontal system now on a rapidly deepening depression
great stuff!

03Stormchaser · Unread post by **03Stormchaser** » Mon 27/09/2004 23:02

Manukau heads observer wrote:hey, its picking up lots of strikes
the sat image confirms an active frontal system now on a rapidly deepening depression
great stuff!

Anyone knows what that triangle means?? does mean the storms center or something??