Low bearing down

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tich
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Unread post by tich »

We might get a sunny spell or two in the afternoon before the southerly arrives which I think will be towards 5pm or a bit later now. But other than that I'm not sure.
The sun has come through at times this afternoon, and Jeffsweather station says it's about 16C with a NE wind. No mention of thunder in latest Canterbury forecast, though some heavy rain is forecast. (no rain in central Chch since early afternoon)
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Unread post by Manukau heads obs »

it was earlier....but not now....
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Unread post by Willoughby »

Thunder has cleared now and heavy rain eased right off.
Was it a squall line or just a cold front?
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Unread post by Manukau heads obs »

a couple of strikes just south of hamilton now show up..
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Unread post by Manukau heads obs »

http://www.portunus.net.nz/weather/boltek600.png
shows were all the strikes were
even one near pokeno...
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Unread post by spwill »

The shower line is now just East of us.Not much rain fell here. Still humid.
Looks like the best storms today were over the Central NorthIsland. The Boltek has worked well .
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Unread post by ricky »

Did miss a few of the hamilton way ones.. i was playing around a bit...

Now there was the first really close storm.. see all those random strikes scattered out from the BOP? they were actually a storm over east auckland, the Boltek manual mentions that effect with storms overhead.. I guess the receivers get overloaded or something, it did put them to the east though...
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Unread post by Manukau heads obs »

alot of action on the kaimai ranges at the moment! !
did you hear any thunder ricky?
Last edited by Manukau heads obs on Fri 29/10/2004 17:29, edited 1 time in total.
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Unread post by NZ Thunderstorm Soc »

...buggerall here, what a dissapointing day :cry: :cry: :cry: :( :x :-({|=

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Unread post by spwill »

Yes, looks like Storms have really got going over Kaimai ranges over the past 30 mins.Might see those cloud tops from here soon as this lower cloud here is clearing. :D
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Unread post by spwill »

Weather has cleared over the City .
I can see good cloud build ups to the North of Auckland Cu + Cb. :D
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Unread post by Thunder »

Good to here guys! Lots of lightning over the central north Island and yes I see that stuff just east of Auckland and pratically over Auckland nearly. Maybe some pics later on of clouds?

I still wouldn't rule out thunder yet........ for Canterbury but it isn't looking great. A bit of sun poking through here now at home in Southshore with the temp around 15 (dewpoint 10), that trough will have to come through soon though which it won't until darkness falls by the looks of things. It has been forecasted to come through around 9 / 10pm from what I can see now but it is quite defined. Yesterday it was more like 4 / 4.30pm.

That cloud cover for the day hasn't been all that helpfull but it did clear to allow the sun through about around 3pm.
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Aaron Wilkinson
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Unread post by Thunder »

Lots of castellanus outside at the moment and the trough looks like it's about to come through. I can see why forecasters use afternoon instead of 4pm / 5pm like I do! I'll do that from now on, makes things a bit easier and I should know better.

I wonder what will happen!!??
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Unread post by Thunder »

You can see the trough marked by the Cb in this sat pic, 6:33pm from Steven G.

No lightning as of yet though, radar will be worth a look soon.
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Aaron Wilkinson
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Unread post by Thunder »

The radar does look good but by the way it looks it seems to not be reading some of the rain properly, I'm sure there's a big area of heavy rain where that Cb is in the sat pic above.
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Unread post by NZstorm »

I was working on a project near Bombay(south of Auckland) and had some heavy squally showers around mid afternoon but no thunder observed.

Nice evening in Auckland with some cirrocumulus floccus.
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Unread post by NZ Thunderstorm Soc »

The southerly went through from 6pm so the day is shagged :(
Nothing to stimulate things now.
MetService got it so wrong

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Unread post by Michael »

well I guess the Gales will arrive in time for the weekend :evil:
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Unread post by tich »

MetService got it so wrong
Got it wrong in yesterday's outlook for today, but the updated forecast for Canterbury today had no mention of thunder in it.
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Unread post by NZ Thunderstorm Soc »

tich wrote:
MetService got it so wrong
Got it wrong in yesterday's outlook for today, but the updated forecast for Canterbury today had no mention of thunder in it.

yes ..well...makes sense as it was so overcast this morning as any thunderstorm development had no show of happening, so forecasts had to be adjusted.

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Unread post by Willoughby »

I give the MetService the tick today, apart from the rain, just showers.

Cool southwesterlies for tomorrow :?
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Unread post by Thunder »

Well nothing tonight..... :( ;)

None the less, it's been interesting looking at the models etc and seeing when and how the system is developing and what it's going to do. Things just developed a bit too late, the potential looked to be there around 3pm if it (the trough) had've come through then but it didn't of course. Maybe only heavy showers would've developed even if it did go through at 3pm due to all that mid and low cloud for the period up to 1pm. As John mentioned, it definately didn't help.

Some ok looking storms up north today which was good to hear (see!) somewhere got storms.

And yes Spwill, definately the situation you put foward for storms in Canterbury is definately the best!

I did a timelapse with my digital camera taking 90 photo's 15 seconds apart and then compiled it (yes that's sitting on the roof for about 23 minutes! lol). It shows the main southely flow near the surface with a small cb that formed offshore that goes east, quite cool and shows the main stearing winds would push storms if they happened east. I haven't got any program to compress the AVI (32mb) so won't put it up on my site. I thought I might be able to as I resized each frame to 300 x 451 pixels (72dpi) and saved each frame as a jpg with 30% compression but the file is still too big!

The cloud (scud type stuff) that was flowing when the southerly just started was great to watch as it was growing quite quickly.

Raining quite good here now and will for a few hours yet as the electrically dead Cb's move over.
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Unread post by Thunder »

Lovely Cb's out there with nice heavy rain which passed over me around 12 / 12:30am. Pitty it's just the wrong time of day so no lightning out there.

Also, brilliant storm over Darwin tonight. I wonder what Deano is up to??!!
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Unread post by NZstorm »

I have only glanced at yesterdays weather, but by the looking at Invercargill's soundings, thunder wasn't really on the cards for Canterbury yesterday as it turns out. Generally for thunder in east Canterbury you require deep cold air advection. By that I mean cold air getting into the upper atmosphere.

Invercargill midday friday 500mb (5000m) temperature -19 (not cold enough)

And the midnight sounding temperature had only cooled to -23, again not cold enough given the surface temperatures and dewpoints.

Look for temps colder than -25C for thunder in Canterbury. -30C is ideal
to create an unstable lapse rate. The upper air needs to be this cold for convection when dewpoints are relatively low. (under 13C).

Compare this to the Auckland sounding, 500hpa temp -15C but cb's developed with thunderstorms in the Waikato. Why, surface dewpoints were around 18C, temps 22C. Its really that dewpoint that was behind yesterdays convection.

By the way TT at Invercargill was 39, at Auckland 48.
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Unread post by NZ Thunderstorm Soc »

Inetresting Cu forms going up at the moment.
Some castellatus, indicating a weak front going through.
Still Ne here.
I have given today a 1 because of this.
Nothing thundery will develop because of this as conditions are not right but if Friday was clear instead of the cloud hanging around, with this scenario, what's happening now, things could of been quite differerent and would of come up with MetService predictions for the day here in Canterbury :)

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