NZ Weather Forum

More sunshine over North Auckland with a cumulus line visible up there otherwise quite cloudy conditions around here, brief sunshine.

Looking southeast from Auckland Intl Airport some reasonable shower/rain activity towards Hunua Ranges and arcing around to the south - and this is now clearly visible on radar.

The NE has just won out again...so we are on a battle front here, LOL
Patches of sun and cloud

John Crouch has kept the watch out in his latest update at 1.30 PM this arvo,

A bit of lightning from the cell developed over Waiuku but the look of it..

Was a good cb waiuku

Tornado Tim wrote:John Crouch has kept the watch out in his latest update at 1.30 PM this arvo,

I'm sorry, I don't understand this reference?

Just finished work. Looks as though the best stuff is not far from home so will head home and re evaluate.

NZstorm wrote:Its not a big instability/big storm day but there will be surface convergence and cold air at 700mb.
I see the DP in Auckland is 12C so enough moisture for pm heat showers and a chance of thunder Waikato/Auckland.

A good forecast NZstorm, it was a low end thunder day, isolated weak storms occurred South Ak/Waikato

Mercer had 18mm in 4hrs today, so good for the farmers there.

Spring has been a quiet period nation wide for thunder especially when you consider the SI West Coast has not had any big set ups yet.

The high and mid cloud did it again today...... frustrating to say the least.

a very usefull 12mm here from a secondary shower area that developed on the sea breeze convergence

Tornado Tim wrote:The high and mid cloud did it again today...... frustrating to say the least.

That's one good reason why you don't want moisture aloft, it tends to manifest in cloud layers.

NZstorm wrote: That's one good reason why you don't want moisture aloft, it tends to manifest in cloud layers.

You do want it, to a certain extent its just how much, otherwise convergence tends to mix out if the layer is too dry (but not an inversion).
In a case of an inversion it can actually help the convection as it puts a limit on how high the straggly convection can go, maximizing the DTSH potential.

reports from that thunderstorm in waiuku that the thunder shook buldings
( I was in the car at the stage but could hear it )

Was a nice CB..developed very quickly (started developing 2pm) and peaked around 2:45

Tornado Tim wrote:

NZstorm wrote: That's one good reason why you don't want moisture aloft, it tends to manifest in cloud layers.

You do want it, to a certain extent its just how much, otherwise convergence tends to mix out if the layer is too dry (but not an inversion).
In a case of an inversion it can actually help the convection as it puts a limit on how high the straggly convection can go, maximizing the DTSH potential.

The USA midwest soundings have dry air in the mid levels. It actually enhances instability as the rising parcel cools a bit quicker if the air is dry apparently.

The inversion CAP has always been the missing ingredient in NZ thunderstorm set ups. The big CAPE numbers in Oklahoma and Brisbane occur because of the warm air around 850/700mb.

A dry mid level in the sounding always seems to give the best thunderstorms here with the strongest lightning.

Scattered Heavy Showers around Raglan this morning, now around Hamilton...

According to Metservice website, Taumarunui had 29mm between 5pm and 6pm yesterday.

The convergence is over Ak city currently,will be out east this afternoon

Picture from Waiuku Yesterday just prior to the big clap of thunder
was some good updrafts

Lots of heavy showers around today. Got a good soaking out west. Thunder just heard out over the hauraki gulf

ben g wrote:...Thunder just heard out over the hauraki gulf

Haven't noticed anything here. Wonder if it was the small intense cell just offshore from Takapuna?

Drove through a heavy shower in Auckland city around 2pm I think. I noticed Ricky got 10mm today but I only got 3mm.

It actually enhances instability as the rising parcel cools a bit quicker if the air is dry apparently.

That sentence I wrote doesn't make sense. But there was a good explanation given on storm track which I can't remember.

I have found a link about the preference for dry air aloft for thunderstorms.

http://theweatherprediction.com/habyhints2/504/