Thunderstorm Risk - 11th,12th October - North and South

[jamie]

Looks like an auckland city and north show tonight. Even if it does fire up now, it's moving so fast it wont be any good before it gets to us.

[Tornado Tim]

Updated Tonight's t-storm outlook:

Amended 8:30pm Friday to include Wanganui, Manawatu and northern Wairarapa in low risk area.

An active front is expected to move rapidly across the upper North Island this evening. There is a moderate risk of thunderstorms across Northland, Auckland,coastal Waikato and the west of the Coromandel Peninsula during this time. These thunderstorms may produce localised heavy rain, strong wind gusts and the chance of a small tornado. In addition there is a moderate risk of LOCALISED DAMAGING WIND SQUALLS exceeding 110km/hr for these areas, and a SEVERE THUNDERSTOM WATCH is in place. A lesser risk of thunderstorms extends south to Taranaki and east to the Bay of Plenty and into Wanganui, Manawatu and northern Wairarapa where a few thunderstorms have formed this evening.

A trough is forecast to move across southern New Zealand today, bringing a low risk of a few thunderstorms to Fiordland and south Westland. This risk spreads to coastal Buller at night. An associated southwest change moves through Southland, Clutha and Dunedin this afternoon and early evening with heavy showers and a low risk of a few thunderstorms.

No thunderstorms expected over the rest of New Zealand.

756c-141a619a300-141a7633a00-141a670d70c.0.png

Tommorow PM:

Forecast reviewed at 8:55pm and the low risk area has been extended to cover all of the North Island outside the moderate risk area. The moderate risk area in the South Island has been extended into coastal South Canterbury.

Unstable west to southwesterlies persist over New Zealand during the afternoon and early evening, along with very cold temperatures in the upper atmosphere. There is a moderate risk of thunderstorms from Auckland to Wanganui during the afternoon. These thunderstorms may produce localised heavy rain, small hail and strong wind gusts. In addition, there is a low risk of these thunderstorms becoming SEVERE and producing damaging wind gusts in excess of 110 km/h.

There is a lesser risk of thunderstorms in the afternoon and early evening over the remainder of the North Island, and small hail is possible as well as localised heavy rain.

Heavy showers should quickly ease over Westland and Buller into the afternoon,but there is a low risk of a few thunderstorms there at first.

Afternoon convergences are likely to form over Southland, eastern Otago, the Canterbury coast and Plains, and eastern Marlborough. In these areas there is a low risk of thunderstorms through to early evening, however the risk is considered moderate in eastern areas of Otago and Southland as well as coastal South Canterbury during the afternoon. These thunderstorms may produce localised heavy rain and small hail.

No thunderstorms expected over the remainder of New Zealand.

756c-141a619a300-141ac899600-141a68341ae.0.png

Winds are still fairly light with a mild 15.8*C on a NW SFC flow.

[Tornado Tim]

Looks like an auckland city and north show tonight. Even if it does fire up now, it's moving so fast it wont be any good before it gets to us.

Yes, man that front is going fast..... Squalls for sure even if no thunder occurs though.

[NZstorm]

well,...it is looking better on the rain radar now...so might start firing up soon

Unfortunately looking weak for lightning now. As the front crosses higher terrain there could be a few orographic strikes.

[Manukau heads obs]

yeah, thats happening now in north taranaki
also is this front a case of upper level thunderstorms?

[jamie]

yeah, thats happening now in north taranaki

i think your right there.

Its bloody warm and humid so plenty of fuel out there for it all. Currently 15.9/14.8.

[Manukau heads obs]

front is coming in real fast alright now
will be here in 30 minutes by the looks
getting real gusty here ahead of it

[NZstorm]

also is this front a case of upper level thunderstorms?

No. I think elevated storms would have been sustained by the jet stream.

[Tornado Tim]

Some Lightning activity going on just north of Palmerston North within the last 20 min.

[Manukau heads obs]

wind change through new plymouth now i see
we are about to reach the max temperature of the day....at 10pm...LOL

[jamie]

59.1 knot gust at Brians just now. Thats more like it!

[Manukau heads obs]

LOL
and real gusty too...shaking the top story around a bit

[jamie]

my pressure is plummeting at the moment.

surprisingly as the front approaches the wind has become more stable at around 40km/h (less speed variation)

[jamie]

holy its hitting now!!!! 82km/h max gust so far

max average was 72.4km/h.

That wind change rates up there with one of the better ones. No way the best but this is pretty darn decent.

[David]

Not much to see here, little bit of moderate rain and gusts 40-50 km/h.

[jamie]

just when i thought it was over we just had the biggest gust I've ever felt in this house (1 year been here) but the anemometer up the farm must have missed it as it was only recording 60ish. It was insane! Must have been about 100km/h. New highest recorded gust tonight is now 83.7km/h.

[Tornado Tim]

Gust up to 64k and a sustained avg wind speed up to 50.3km/hr!

[jamie]

Hamilton is about to get hit by some really heavy rain. We just missed it but got a few massive drops. Radar shows it slid down to the west of me. Will get most of western Hamilton.

Not sure why but the BOP radar doesn't show it to be as severe as the Auckland radar.

[ben g]

Only moderate rain here wind has died right off

[jamie]

some nasty squally showers are coming through this morning.

fantastic looks Cb's all over the place too.

[NZstorm]

Upper level trough coming into the North Island this afternoon but cool blustery conditions on the surface.

Canterbury could be worth the chase today with an outside chance of some reasonable hail.

[David]

Torrential shower with hail here a few minutes ago. Think I heard some distant thunder too

[Nev]

Yeah, have heard about 4 very long distant rumbles in the last 10 mins or so. Must be much further south. The odd brief heavy shower here too.

[NZstorm]

Certainly looking squally with those cb's today.

[Manukau heads obs]

yes, some great looking CB's around , great looking anvils
they are moving fast though...by the time you think that would make a good photo...its moved away!