Sth Auckland Funnel/Spout - Apr 20

[Manukau heads obs]

a warm 23C in Waiuku
with a northerly wind, bent by a weak sea breeze trying to develop
and so some convergence, and low level instability and bingo
a funnel cloud that went all the way to the ground!
(just south of Waiuku around 4:45pm..last 10 minutes...I could see it from here, 28km away (CU cloud had an overshooting top (photo shows that...had weakened by the time I took the photo)

[Hordur]

Thanks, brilliant pictures and nice analysis of what happened.

[Manukau heads obs]

lets call it a landspout
because if this was over water it would have been a waterspout with spray on the water...
(I have seen them form from similar low topped CU)
I wonder if this might have been over the Waikato River even (to help with the condensation funnel?) as reports are that it was near Aka aka, which is south of Waiuku and near the River

[Hordur]

Here is a doppler radar image from 4:45 this afternoon.

Doppler.JPG

I think moisture from the Manukau Harbour will have helped with this.

[Hordur]

A reflectivity radar image from the same time:

Akreflectivity.JPG

[Richard]

Interesting photos

[Nev]

Wow! Some great pics Brian. Stuff have a few more pics in this story…

'Waterspout touches down in harbour during Auckland storms' - Auckland Now

[GreggWard]

Nice pictures Brian. It looks quite impressive.

[Weather Watcher]

Just to clarify the radar images Hordur has posted above. They're both the same reflectivity image from the Auckland radar - they are just using different colour scales.

[jamie]

I'll ring around a few farmers tomorrow and find out more about it.

[Manukau heads obs]

There is a line of ranges (Port Waikato Hills etc) just south of Waiuku (i.e otherside of the river) that do act as bit of a barrier to the northerly that runs down the Waiuku estrury from the harbour...and so would have helped with some uplift

[03Stormchaser]

I see metservice called it a waterspout, was it?

[Manukau heads obs]

it was over land going by the rsin radar..although close to the waikato river.people from the city looking south probably thought it was over tbe Harbour..maybe where tbr confusion is

[Hordur]

I see metservice called it a waterspout, was it?

Strictly speaking it should be called a waterspout if it was over a body of water but a funnel cloud over land.

http://en.wikipedia.org/wiki/Funnel_cloud

"Cold-air funnel clouds (vortices) are usually short-lived and generally much weaker than the vortices produced by supercells. Although cold-air funnels rarely make ground contact, they may touch down briefly and become weak tornadoes or waterspouts.
A shear funnel extending from a generic cumulus cloud. Observed in northern Texas by a member of the VORTEX project.

Unlike the related phenomenon associated with severe thunderstorms, cold-air funnels are generally associated with partly cloudy skies in the wake of cold fronts, where atmospheric instability and moisture is sufficient to support towering cumulus clouds but not precipitation. The mixing of cooler air in the lower troposphere with air flowing in a different direction in the middle troposphere causes the rotation on a horizontal axis, which, when deflected vertically by atmospheric conditions, can become a funnel cloud.[1]

They are a common sight along the Pacific Coast of the United States, particularly in the spring or autumn.[1]"

That information is generally correct but seems to be biased towards conditions in the USA. This passage is not correct for New Zealand conditions: "where atmospheric instability and moisture is sufficient to support towering cumulus clouds but not precipitation." The cloud bases associated with such events in the USA may often be too high for precipitation to reach the ground. This is however not the case in New Zealand where precipitation may reach the ground.

[03Stormchaser]

it was over land going by the rsin radar..although close to the waikato river.people from the city looking south probably thought it was over tbe Harbour..maybe where tbr confusion is

It looked like a waterspout when i first saw it, but radar confimrs otherwise but then Metservice ssaid this via stuff:

While many assumed it was a tornado, MetService said it never actually hit land.

"It's a spiral of wind, not very strong and doesn't have much of an affect on the ground. It is much weaker than a tornado and doesn't pose a risk," said Hordur Thordarson, duty forecaster at MetService.

He said the spout was formed by easterly and westerly sea breezes coming together over Auckland.

Or is this the media twisting there words? Wouldnt be the first time

[Orion]

Great photos of an interesting phenomenon!

[Hordur]

it was over land going by the rsin radar..although close to the waikato river.people from the city looking south probably thought it was over tbe Harbour..maybe where tbr confusion is

It looked like a waterspout when i first saw it, but radar confimrs otherwise but then Metservice ssaid this via stuff:

While many assumed it was a tornado, MetService said it never actually hit land.

"It's a spiral of wind, not very strong and doesn't have much of an affect on the ground. It is much weaker than a tornado and doesn't pose a risk," said Hordur Thordarson, duty forecaster at MetService.

He said the spout was formed by easterly and westerly sea breezes coming together over Auckland.

Or is this the media twisting there words? Wouldnt be the first time

Stuff usually do a great job reporting the weather and it is hard to get every detail 100% correct. There may in fact have been a waterspout over the south of the Manukau Harbour for a time. Since conditions were conducive to the formation of waterspouts/funnel clouds there may well have been both a waterspout and funnel cloud in the vicinity of Auckland today.

[Manukau heads obs]

the Manukau Harbour area was basicly cloud free in comparison.only clouds around was in a line from
waiuku to Papakura

[NZstorm]

April is a good month for these when you get the overlap between the surface humidity and the cold air aloft. Light winds were a factor in this landspout.

[spwill]

Excellent photo's there Brian.
I was on Waiheke Island this afternoon, I did notice those afternoon shower clouds to the southwest of Auckland.

[Nev]

Agree with Brian that the radar imagery tends to suggest an inland waterspout over the Waikato estuary.

[Manukau heads obs]

this picture is of when I first photographed it (after I got the phone call (which I was like, whaaat...as there was blue skies here...and it looked impressive...by the time I went back in to get my phone it was already starting to weaken)

ps, I know from the angles of the road and houses that the photo I posted earlier (with my daughter running towards it (taken by other daughter) means it was SSE of Waiuku....and other photos support that..
it was basicly in the Aka Aka area (which is near the Waikato River)
Hopefully Jamie can track down a dairy farmer that was close to it

[jamie]

Brian do you think near the old dairy factory at aka aka? I know heaps of farmers so I should be able to track a couple down that saw it well.

[Manukau heads obs]

I have drawn in where I think it would have been
(maybe even a bit more to the SSE of where I have drawn it thinking about it more)
(based on how there was a faint rainbow near it...i.e so it did have some (big drops?) rain falling near it and it was blacker behind it (heavy rain), more to the SW (see the first photo I posted), as per the rain radar)
so, yes, in that Aka Aka area

[jamie]

Oh right so that's further north of the river than I was thinking. That could be near the stock car track or is it to the west of that.