Convective Possibilities, North Island - 9,10,11 Feb 07

GraemeWi · Unread post by **GraemeWi** » Sun 11/02/2007 10:08

Just so I can remember what thunder sounds like in the slack months...

http://www.gwprojects.org/public/Thunder.wmv

squid · Unread post by **squid** » Sun 11/02/2007 11:14

awesome funnel pics well done btw there is a programme that you can use to get rid of unwanted powerlines in your pics

GraemeWi · Unread post by **GraemeWi** » Sun 11/02/2007 12:18

squid wrote:awesome funnel pics well done btw there is a programme that you can use to get rid of unwanted powerlines in your pics

Something like Photoshop ($$$) or Gimp (free) together with a digitiser drawing pad are ideal

GreggWard · Unread post by **GreggWard** » Sun 11/02/2007 12:48

Great coverage of the storms including photos, videos and Metservice info (confirmation by Paul of Matamata storm, storm height and probability of hail), yesterday. Well done.

spwill · Unread post by **spwill** » Sun 11/02/2007 12:51

http://www.gwprojects.org/public/Thunder.wmv
Nice one Graeme.

Looks like the better show yesterday was over Auckland especially with that Funnel cloud.
By the time I got into Waikato yesterday afternoon most of the storm activity was west of SH 1 which put us on the shaded spreading anvil side of the Cb's, not the best place to watch them. The roading to the west is poor down there..

Manukau heads obs · Sun 11/02/2007 13:18

best place to view the action was right here , looking across towards auckland (mainly south auckland, where the more intense and organised cb's were (my webcam just got the edge of the northern end of those)

it was very impressive viewing from here....kicking myself i did not have my camera where i was at the time...

the wide said to me at 3pm...do you think we will get those CB's? (that had developed on a sea breeze convergenece line over auckland)..i said, not way, never, not....they always move further away,..the SW sea breeze wins.....not this time!!! (altough it was a strengthening SE over the area (turned more easter behind this line) that won out

NZstorm · Unread post by **NZstorm** » Sun 11/02/2007 13:42

Looked to be a boundary passing through mid to late afternoon that triggered a lot of that convection, particularly the South Auckland storm.
Juicy 18-19C dewpoints and very warm temps ensured the thermodynamics were good. It was interesting the storms moved toward the NW and the anvils were blowing off toward the east in the upper westerly. An interesting day and like spwill I regret going south of the Bombays. The Auckland storm with its funnel was the catch of the day.

As for Monday, I would like to see Met Service get it bang on again but I am concerned about the moisture.

Paul Mallinson · Unread post by **Paul Mallinson** » Sun 11/02/2007 13:44

Our radar hail size diagnosing routine showed 3 areas of 23mm hail in the storm located just south of Auckland City at 4:15pm (yesterday).

Paul

Manukau heads obs · Sun 11/02/2007 13:51

wow, then that must be hail that you can see on rickys photos...the white streaks....just a few of them, far apart....(which is characteristic of large hail)

An interesting day and like spwill I regret going south of the Bombays

I was not expecting shuch a great show over the south auckland area.....been years since its been that good...but it does happen from time to time...but the chances are the great waikato is the safer bet

some convection now again over auckland as there was a break in the upper clouds to allow heating there....so there is still instability
but yeah DP's are lower now

Willoughby · Unread post by **Willoughby** » Sun 11/02/2007 14:07

As the first storms were gathering in eastern Waikato the boltek was recording up to 64 strikes a minute! And I think there was wind damage from that storm in Morrinsville including hail.

Heard there was flooding around Te Kuiti too rolling a truck.

Paul Mallinson · Unread post by **Paul Mallinson** » Sun 11/02/2007 14:11

NZstorm wrote:Looked to be a boundary passing through mid to late afternoon that triggered a lot of that convection, particularly the South Auckland storm.
Juicy 18-19C dewpoints and very warm temps ensured the thermodynamics were good. It was interesting the storms moved toward the NW and the anvils were blowing off toward the east in the upper westerly. An interesting day and like spwill I regret going south of the Bombays. The Auckland storm with its funnel was the catch of the day.

As for Monday, I would like to see Met Service get it bang on again but I am concerned about the moisture.

Currently we still have dewpoints over Northland of 17 to 18C. I see this last hour Whangaparoa has reported a dewpoint of 18C in a northeasterly. And there are 16s down the Waikato Coast coming in on the sea breeze.

The way I see it, yesterday, the heating formed sea breeze convergence zones along the west coast from the Auckland area south to Waitomo and on the Coromandel Pen and Wrn Bay of Plenty coasts. As the heating progressed in the afternoon, these troughs migrated inland to meet fairly centrally in Waikato (these of-course triggered the convection). Eventually later in the afternoon as the heating started to weaken, the sea breeze from the west weakens and the whole setup migrates to the west because of the prevailing easterly flow.

Interesting point about the direction of the anvil blow off being from west to east. The high level winds were certainly westerlies.

Paul

Manukau heads obs · Sun 11/02/2007 14:25

yes, wind NE here now too, and DP slowly increasing...16.5 here now

good build ups occuring now..same places as yesterday...south auckland and bombay hills area.....

Manukau heads obs · Sun 11/02/2007 14:31

Interesting point about the direction of the anvil blow off being from west to east. The high level winds were certainly westerlies.

you can see that well on my animation
http://www.weather-display.com/aucklandcb.wmv
when the very top hit that jet stream/remains of cyclone nelson cloud, it got blown off to the east quickly....which is where the wind shear for the verticaly lifted spiral core for rickys funnel cloud came from...

Manukau heads obs · Sun 11/02/2007 21:36

some interesting convection and rotation here this afternoon and this evening (and we got 8 mm of rain in a heavy shower)

spike_01 · Unread post by **spike_01** » Sun 11/02/2007 21:58

That Low on the way down is gonna keep the Easterlies on the go...

Manukau heads obs · Mon 12/02/2007 07:15

overcast today...with scattered rain about....
whole different kettle of fish today....

NZstorm · Unread post by **NZstorm** » Mon 12/02/2007 07:18

Thunder risk doen't look there today to me, but should be some showers again today from lower topped cu buildups.

EDIT

overcast today...with scattered rain about....
whole different kettle of fish today....

looks to be a weak surface trough over us Brian.

Manukau heads obs · Mon 12/02/2007 08:35

there was action around here last night...and heavy rain over the waitaks...
i did observer a small funnel cloud...tried to get it on camera....which then wanted to flash...by the time i got the flash turned off, it was not so good

also there was a an area of convection that was rain free , with some outer rain bands,...they were slowly rotating around the central rain free convection area...i.e a rotating (slowly, but still rotating) CB, right over the peninsular here (Helped by a weak sea breeze on the coast, a NE coming off the harbour, a mid level SE wind and an upper level NW wind....i.e lots of windsheer!

no, it sounds like,
<cough>
, bullshite, but thats what I observed!!
ok, photo , to the right of the power pole, under the wires

next photo was later on....nearly dark....nice colours in the sky...differenet light areas etc....dying havy rain cb over the waitaks at the time

Willoughby · Unread post by **Willoughby** » Mon 12/02/2007 09:22

Looks like we're heading for a max of ~19Â°C. No 26 today..

Manukau heads obs · Mon 12/02/2007 09:57

i see met service thinks there will be a sea breeze convergence over the nth taranaki/king country area......
i think the eaterly wind flow is too strong today and not enough sun getting through?
(maybe down that way less cloud cover at the moment, and lighter winds though?)

NZstorm · Unread post by **NZstorm** » Mon 12/02/2007 11:28

there was action around here last night...and heavy rain over the waitaks...

I saw the showers from my place last night. Would have been from low topped cb. And I would say there was likely funnel cloud or two around yesterday. The unstable easterly pattern seems to favour their development, particularly over the Manukau region.

GraemeWi · Unread post by **GraemeWi** » Mon 12/02/2007 12:41

There was a nice cb out to the west last night. I've got a few shots of it on my camera. Later on I was out at Muriwai and observed a strong rain-foot from it out to sea.

squid · Unread post by **squid** » Mon 12/02/2007 13:22

that low that is to the north of NZ is not the remains of Tc nelson it is another low that developed in the CS just east if carins that was under a TC watch for a few days. TC nelson died over CYP

Manukau heads obs · Mon 12/02/2007 13:39

talked to some other people, and they notice the circulation in the clouds over the peninsular....and they thought a tornado was going to develop!...thats how noticeable it was....but I kept on doubting my own eyes....saying..nah,,your not in kansas!
i actualy also saw a wall cloud develop to for a few minutes,...classic
/ \ shape and all

the whole thing was a mini (i know, not that word!) mesocyclone, right over the top of the peninsular here....

the high res rain radar should have shown up the circulation that was occuring....anyone got access to that (metconnect)?

what you saw graeme was what we had earlier,,,that kept on moving north

spwill · Unread post by **spwill** » Mon 12/02/2007 16:05

Interesting report Brian, we've not seen much seabreeze convergence over Ak area this summer so far.

Have seen a funnel cloud out of very shallow Cu over Ak before.

Gloomy cool weather here today.