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

[Tornado Tim]

Time for a new Thread

Thunderstorm outlook for October 11 (Afternoon/Evening):

Issued at: 8:33pm Thursday 10 Oct 2013

Forecast amended 8:30pm Thursday and minor changes made to moderate risk area over North Island (now including coastal Waikato but not all of the Coromandel Peninsula).

The trough should move slowly across Fiordland and south Westland during the afternoon and early evening, with a low risk of a few thunderstorms. An associated southwest change is forecast to move through Southland and south Otago/Dunedin during this time. The combination of afternoon heating, cold temperatures in the upper atmosphere and surface convergence leads to a low risk of thunderstorms in this area.

An active front is forecast to move out of the north Tasman Sea tomorrow and across the upper half of the North Island at night. There is a moderate risk of thunderstorms over Northland, Auckland, coastal Waikato and northwest Coromandel Peninsula in the evening. These thunderstorms may produce localised heavy rain,and strong wind gusts of 90 to 110 km/h. In addition there is a low risk of these thunderstorms becoming SEVERE with damaging gusts in excess of 110 km/h and the possibility of small tornadoes. A lesser risk of thunderstorms extends further south to Taranaki and east to Bay of Plenty.

No thunderstorms are expected over the rest of the country.

[Manukau heads obs]

should read, possibility of micro bursts, instead?

[03Stormchaser]

It almost does now,Localised Wind Squalls

[Manukau heads obs]

ah, yes, in reference to
http://metservice.com/warnings/severe-t ... torm-watch

thats actually OK as they will be squally type thunderstorms

[NZstorm]

The midnight models were not looking so good as previous runs on tonights front. Still looks gusty anyway.
And still worth watching this set up to see whether instability can occur.

[Manukau heads obs]

yeah , the latest marine forecast has not changed upwards
in the past wave depressions like this have caused serious damage in this area

[jamie]

what are you expecting to get in the next 24-48 hours brian? in terms of wind gusts. If the weather is atrocious tomorrow morning i might go for a drive up the heads.

[Tornado Tim]

what are you expecting to get in the next 24-48 hours brian? in terms of wind gusts. If the weather is atrocious tomorrow morning i might go for a drive up the heads.

Id be tempted to go up too if it's really blowing.......

The warm frontal cloud doesn't really want to go away atm, completely overcast and dull..

[Manukau heads obs]

cool on a weather meet at the signal station tomorrow morning
there is now an anenometer there...that I donated...a 'Maximum gauge'
i.e analog dial one...like the one I damaged, LOL

[Tornado Tim]

i.e analog dial one...like the one I damaged, LOL

I still feel for you about that day, LOL

I was surprised how you reacted, I would have been more visibly pissed off!

The Storm risk goes up for the Waikato region tomorrow as the flow turns WSW to West. The distrurbed westerly flow will be in full swing!

Brian you are in a ideal place for these types of setups, It must be so cool to see distant storms over the Tasman flickering away at night.

Anyway T-storm outlook for Tomorrow PM:

ssued at: 10:22am Friday 11 Oct 2013

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 from Northland to northern Manawatu, also Bay of Plenty. Afternoon convergence zones are expected to set up in Wellington, south and coastal Wairarapa, and Hawkes Bay and Gisborne north of about Wairoa. In these areas, scattered heavy showers and small hail are possible along with a low risk of thunderstorms.

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 Otago during the afternoon. These thunderstorms may produce localised heavy rain and small hail.

No thunderstorms expected over the remainder of New Zealand.

Interesting to see the Moderate risk for Otago, I best broaden the scope for the potential event down south if any our southern friends want to chase etc....

[03Stormchaser]

Will be busy chase weekend. Sat tstorm and monday wind!

[Manukau heads obs]

so the threat of tornadoes has been dropped I see
edit,ops, my bad, was looking at tomorrows thunderstorm outlook


yes, tomorrow could be a good day for squally CB's

[spwill]

I have a busy weekend on so no chasing for me.

[Manukau heads obs]

I see some CB's are starting to fire ahead of the front...which is building into the tasman like a giant wave

[NZstorm]

I see some CB's are starting to fire ahead of the front...which is building into the tasman like a giant wave

Lightning starting to show up now, great early sign!

[Manukau heads obs]

yes, and more and more along the frontal line
NW wind slowly increasing here

midnight ETA going on my reckoning

[Richard]

Looks to be a decent sized storm west of Dunedin,not often you see red within this blind spot area of the radar system

[jamie]

I'm still a NNW here. Got that humid drizzle back again now.

The jet stream is really getting these storms to fire. The colored infrared sat image shows they anvils are being displaced a long way. Some strong winds aloft.

Brian you'll have a great light show tonight as it approaches late tonight.

[Tornado Tim]

Brian you'll have a great light show tonight as it approaches late tonight.

Yes he will!, I would constantly stare from the West.....

[jamie]

I see you have already topped the 50 knot gust mark Brian. That's a very good sign.

[Manukau heads obs]

yup, wind really ramping up now here, real gusty too

[NZstorm]

500mb flow through those storms is 85knots. The jet stream is nicely placed to get the convection firing.

[Manukau heads obs]

so thats the first (with the better chances of lightning activity) front showing on the rain radar I assume..
so the question is, is it going to develop more, west of me here, or is it only the far north thats going to get clipped by a few CB's?

[Manukau heads obs]

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

[ben g]

You know you have a problem when you are going to a party and not drinking, just so you can waste time till the front arrives with out falling asleep.