Thunder possible North Island - Jan 11/12

[NZstorm]

A weak upper trough over the upper North Island 500mb13C coupled with low level moisture DP18C and daytime heating Temp25C will lead to the airmass becoming unstable over the west and upper North Island today. There is no capping so any convergence this afternoon will push up showers with the possibility of thunder. We are looking for the easterly flow to converge with sea breezes in the west. The thunder risk area is western Waikato, Waitomo.

Shower/thunder activity will be proportional to the amount of heating/convergence today. There are no upper level dynamics so the best we are looking at is pulse storms.

[Manukau heads obs]

SW died here at 5am
clouds are from the east now
there is patches of blue sky, so some heating
not sure if the sea breeze will develop...would have to stay with the blue patches
will be watching!!!
thanks NZStorm for the heads up

[NZstorm]

not sure if the sea breeze will develop

Yes, thats the big weakness with this set up unfortunately. You would think mid Feb should still be good for sea breezes, but as we move into late summer that whole sea breeze thing weakens off.

[Tornado Tim]

Fairly High CAPE values in the GFS But CAPE depends of the moisture feed.

It very much depends if the two breezes meet as mentioned above.

Overcast atm with a surface temp expected to reach around 26°C. Upper air @ 500mb -14°C (which is a bit too high in my opinion)

What it will come down to is: Seabrezzes providing the moisture feed and some decent DTSH to make the air unstable.
The TT index is looking quite favorable at around 50-55 and the KO Index around -16 and BI of less than 80, but those indexes only sample sections of air and dont take into consideration the lower to middle layers.


I am still not sure if this event will come off, will have to see.

[Manukau heads obs]

it might be a late sea breeze...that will favour a west coast only event...i.e me...he he he

we now have a very light SE wind here now..
that could easily become SSW with a sea breeze influence late morning/early afternoon

edit now ESE

[Tornado Tim]

Forgot to add the CAPE chart, for 4 PM Today:

[David]

edit now ESE

still SSW in Howick...

[Manukau heads obs]

I have seen that alot...where a general SE flow gets bent around the Hunua ranges and then in between the waitakere ranges, and becomes a S or SSW over the auckland Isthums area

[jamie]

sun becoming more more evident here. shouldnt be too long and it will be out in full force.

[spwill]

First ingredient of the day needs to be some good daytime heating, quite sunny here now but still a cool feel to the day, 21C,dewpoint16C.

[NZstorm]

The dewpoints in the BOP and Gisborne are 18C and thats the direction the moisture will advect from.

[Tornado Tim]

Hmm Cloudy to Overcast, It really needs to clear now for something to happen

[spwill]

Enjoying mostly sunny conditions here , Greylynn has 25C ,dp 18C, no showers for the Auckland region yet.
BOP radar showing showers over the BOP

[Manukau heads obs]

getting warmer and warmer here
NE breeze here now
no sign of sea breeze... yet...

[NZstorm]

I see Raglan has 26C but a light NE wind.

No 00Z NZWP sounding today.

[Tornado Tim]

Moisture is definitely here
19-20°C Dps!

[Tornado Tim]

CB ova kaimais, red/purple on Radar

[Manukau heads obs]

sea breeze developing on the coast line here
I can see showers developing in land though to my SE!
I see the Kaimais have heavy showers now too

[NZstorm]

Some glaciated looking tops out to SE of Auckland. Nothing particularly strong looking though.

[Manukau heads obs]

getting some strikes showing up to my SE now

[NZstorm]

Yes some big tops there now. Have been getting static on the am radio.

[NZstorm]

According to lightning tracker there is a weak storm just inland from Port Waikato.

[Manukau heads obs]

what they look like from here

[David]

I could see some cells to the S as well, but didn't bother trying to get a photo as there's too much scrappy grey cloud in the way. Lovely day here with plenty of sun, max 24.7C, dewpoint has risen steadily through the day to 19C.

[spwill]

I diid a drive south around 3pm but had to be back in Auckland by 5.00pm.
photo of clouds building near the Bombay Hills, North Waikato, I see there has been some isolated TStorm activity in that area.