NZ Weather Forum

Storms a risk tomorrow for upper half of the North Island with the Low Pressure system coming through the South Island on the 2nd.

With the Warm Moist NW creating quite favourable theta-e temps, combined with fairly cold upper level temps throughout tomorrow (-22 to -24*C) , shower activity will get going quite quickly.
Thing is, looking at the atmospheric profile tommorow, there is no limit to the free rise of convection, therefore showers will most likely muddy the environment for decent storms to develop. (I presume this is why the Metservice Convection Desk issued a Mod risk instead of High).

The frontal passage will be something to watch tomorrow evening on the West Coast. SFC Sea temps around Auckland/Waikato/BOP are at 15*C, Northland up to 16.7*C.
Those temps should be sufficient for thermal differentiation esp taking into consideration theta-e and potential latent heat release. A pitty that the main jucy shortwave passes through in the middle of the night Wednesday into Thursday.

Then we return to that oh-so-lovely SW flow with embedded scrappy showers Thursday.
Metservices Thunderstorm Outlook:

Metservice wrote: During the afternoon, temperatures continue cooling aloft over the North Island,allowing widespread shower activity to form in response to afternoon heating.

There is a moderate risk of afternoon thunderstorms developing from Bay of Plenty to the central high country and northwards to Northland. These thunderstorms could bring rainfall rates of 10-25mm/hr and hail of 5-15mm. This activity is expected to ease from the west from late afternoon, clearing eastern Bay of Plenty in the early evening.

During the evening, a front is expected to cross the northwest of the North Island supporting a band of heavy and possibly squally showers. Over western areas from Northland to Taranaki, there is a moderate risk of thunderstorms with brief heavy rain, squally wind gusts to 90km/hr, and the risk of one or two small tornadoes about the coast.

A larger low risk area extends from East Cape to Wairarapa, the Marlborough Sounds and onto Westland, as indicated on the chart.

Elsewhere, no thunderstorms or significant convection expected.

The first front of the day out to the west of the NI now with isolated tstorms on it.

Yea too early for any heating sadly.

The Piha webcam might be interesting today http://www.takeabreak.co.nz/accommodation/piha.asp

some nice looking cb's to my west now
but not very "punchy" yet

A fine day so can see that line to the southwest nicely from here, a few towers in there.

Just after 9am I drove along the ridgeline of Manuka Road in Bayview, heading West, which affords a good view of the Waitakeres, Hobsonville, and Upper Harbour Drive to the North and West. Huge stack of cloud shrouding the Waitakeres and on the Northern end of it, a really nice mushroom-shaped one that looked like it had aspirations to be an anvil. The sun felt really warm. 13.6 here at the moment with a DP of 11.4 and humidity at 87%

first shower line through here now
was a good one

A dry sunny morning here, up to 18C.
Cbs to the southwest earlier drifted away southwest, photo.

A heavy 3mm shower early afternoon otherwise quite a nice day here.

Lightning data shows a small amount of activity has occured Waikato/Northland.

I had thunder rumbling at 10am at Mercer. That shower skirted to the south of Mercer.

Cb line running into Waikato currently can be seen from here, Tstorms over the sea.

Just had a shower come thru at home that had lots of hail in it. Biggish hail too. Bigger than pea size. But not by much.

Now have thunder from the cell just north of Raglan.

Was a fairly nice day here, even got to 19 degrees

Some distant lightning observed in the west /nortwest with that front

Good lightening and thunder in Swanson / Ranui, both near and far. The storm looks to be tracking to the south east.

Can hear distant thunder here in Grey Lynn, odd flash in the west.

Lots of thunder here in Laingholm. Warning issued I see...

http://cdem.co/viewer.jsp?alertId=91
= severe thunderstorm warning, West Franklin, Pukekohe

and
http://www.metservice.com/warnings/seve ... m-warnings

Interesting about that warning and watch.

I have lots of thunder here and getting closer.

was good lighting show Karaka area when I drove through
but it died quickly
was another frequent flashing cb out over the coast west of Waiuku too

Can see the odd flash here from that cell over the top of Coromandel.

Seeing and hearing plenty of it. Looks like most of it will miss me tho.

Some great looking cells in the Gulf at sunset ( photo at dusk) which moved onto Coromandel, could see distant Cgs .