Low risk of thunder for Canterbury Friday 15th - Sunday 17th

tich · Unread post by **tich** » Fri 15/09/2006 18:06

The word low must be emphasised. MetService says there's a small risk of thunderstorms for Canterbury this afternoon and again tomorrow afternoon. I'd say there's little chance today as (even though it's been a warm day) the sun should be going down soon and there doesn't seem to have been any significant change in the weather up to now. (variable high cloud)
Tomorrow may be more suitable for storms, as it looks like colder air should spread over the South Island. However, the airflow seem to be more west than southwest, so chances of Canterbury getting anything are diminished.

NZstorm · Unread post by **NZstorm** » Fri 15/09/2006 19:12

The convective season in the east of the country starts about 20th of November (when sea breeze activity gets fired up). You need a special weather set up to get thunderstorms before then.

NZ Thunderstorm Soc · Fri 15/09/2006 19:50

Even though the sky was rather castellataus looking this afternoon, I had no warning out for today.
Very weak conditioning ...
...and when the NW came through around 4:15pm YES

no potential for a 1
My thunderstorm season runs from October the 1st but then thunderstorms can occur at any time as we have known over the past few years.

JohnGaul
NZTS

Storm Struck · Unread post by **Storm Struck** » Fri 15/09/2006 20:59

We have had some good storms even before storm season gets going even right back to August although these were during cold outbreaks.
So September Thunderstorms would not be unusual.
How ever yes NZstorm it is after 20th of November we have better risks for thunder and of much higher occurance.
I would tend to think Sunday late afternoon/evening looks best chances for thunder although with the flow being more W-SW most of the shower activity is likly to be offshore or hugging the Penninsula but hopefully something.
You might see some afternoon build ups to the SE as usual with a NW flow but probly wont go far tomorrow.
Cheers
Jason.

03Stormchaser · Unread post by **03Stormchaser** » Fri 15/09/2006 21:00

For me its 1st october, but more likely covection 2 months prior to christmas. From my limited knowledge of storms etc November has seemed a relatively active month.

NZ Thunderstorm Soc · Fri 15/09/2006 21:15

....according to ECMWF, later next week looks quite interestering

JohnGaul
NZTS[/b]

NZstorm · Unread post by **NZstorm** » Fri 15/09/2006 21:25

I would tend to think Sunday late afternoon/evening looks best chances for thunder

But look at the forecast barometer for Sunday over Canterbury, above 1010hpa. Thats quite ridgey! A ridgey SW in September is not a good situation for thunder. Looks like the coldest upper air will stay south of the SI.

according to ECMWF, later next week looks quite interestering

Thats what I mean by a special weather situation.

That one is worth watching.

mikestormchaser · Unread post by **mikestormchaser** » Fri 15/09/2006 23:01

hmmm i love thunderstorms and they are so exciting to watch.But i havent got the skills to know how and what types of weather is good for thunderstorms.I just guess on the day and i can tell when one is going to form u can just tell by the weather situation on the day and the atmostphere! but as 03stormchaser said, 1st of october sounds pretty good for the start of thunder.

Storm Struck · Unread post by **Storm Struck** » Fri 15/09/2006 23:11

Yeh Sunday not too much in favour now perhaps a slight risk tomorrow but as I said more offshore than anything.
Just remember one of our best rememberd storm days was on Labour weekend 2002 with unstable skies and heavy scatterd showers and thunderstorms everywhere. Plus the hailstorm around Hornby,Hallswel and the tornado in Tai Tapu. October that was.
How can I forget the Funnel cloud on October 16th 2004 and my first to be seen

.
One thing I do enjoy is in December usually just around Christmas we can get 4-5 days of thunderstorms in a row it's great i am hoping that happens this year.

Cheers
Jason.

Manukau heads obs · Sat 16/09/2006 08:58

both rick'ys and mine lightning trackers are picking up CB's in the cook straight area and west of the manawautu at the moment
foggy's seems to have the strikes a bit too much to the SSE?

anyway, the wellington detector is not picking these up at all
must be the hills around wellington?

NZstorm · Unread post by **NZstorm** » Sat 16/09/2006 09:07

more offshore than anything.

Yes, they can occur well offshore.

both rick'ys and mine lightning trackers are picking up CB's in the cook straight area and

Fairly stable down that way though.

RWood · Unread post by **RWood** » Sat 16/09/2006 09:24

All I can see is sunny skies with occasional small patches of passing high cloud, light winds in the westerly sheltering. I like it but a drama-seeker would find it totally boring.

Manukau heads obs · Sat 16/09/2006 09:28

they must be then way further south of the cook straight area....SE of canty then?
(where the front it)
when the signal gets bounced over the horizon, thats the problem, it plots it too close

i am still getting used to how to interpret the boltec data

( guess best thing is to correlate with the ozy map)
http://www.weatherzone.com.au/currentwe ... p?state=NZ
with lightning option turned on

it shows lots of thunderstorms to the south and SE of the SI

i think its when the boltec plots them all in a line , thats when you know they are alot further away...?

03Stormchaser · Unread post by **03Stormchaser** » Sat 16/09/2006 13:21

Metservice still seem keen on thunderstorms for later today. Im not sold though.

Valid to: 12:00 am 17 Sep 2006 NZST
Issued at: 9:22 am 16 Sep 2006 NZST

A cold front will move over the South Island today to reach the lower North Island by midnight tonight. As it does so, a south to southwesterly change will move up the east coast as far as about north Canterbury before moving offshore. This wind shift, along with quite cold temperatures aloft, will probably trigger thunderstorm activity offshore to the east of the island,but there is a moderate risk that some may develop on the change in coastal areas from about Timaru to Banks Peninsula. If these storms develop, they are likely to produce small hail and strong outflow gusts in the 90-110km/hr range. Further inland, the risk of thunderstorms is lower.

The same front will bring a low risk of thunderstorms to the west coast as far north as Hokitika this morning and afternoon, and over Buller and northwest Nelson this evening, and from Kapiti to south Taranaki tonight.

From this evening, another cold change will brush the Southland and Otago coasts bringing very strong westerly winds to the area. This feature will be accompanied by fast moving squally showers and wind gusts as high as 120km/hr or more. A wind warning will be issued for these conditions this morning.

Elsewhere, no thunderstorms or significant convection is expected.

Storm Struck · Unread post by **Storm Struck** » Sat 16/09/2006 13:21

Cant see any threatning clouds out at the moment just high cloud and patchy blue sky.
Breezy NW wind and warming up already on 21.8C.

See what happens

.
Cheers
Jason.

NZstorm · Unread post by **NZstorm** » Sat 16/09/2006 14:25

Yes, too dry over east NZ today for thunder. Maybe at the Chathams.

Willoughby · Unread post by **Willoughby** » Sat 16/09/2006 14:33

Manukau heads observer wrote:both rick'ys and mine lightning trackers are picking up CB's in the cook straight area and west of the manawautu at the moment
foggy's seems to have the strikes a bit too much to the SSE?

Some strong strikes there Brian, but they're well beyond NZ, at around 50.5Â°S where the bright cloud is.

The Central Plateau refracts the sferics here more than yours in Auckland.. which is why my direction isn't that flash down there (even for Westport storms)

Paul Mallinson · Unread post by **Paul Mallinson** » Sat 16/09/2006 14:43

The southerly change is moving north off the south Canterbury coast and arcs back into the Oamaru area. There is a line of showers trying to build back towards the coast on the radar. I agree the dry westerly is very dominant, but won't give up yet with the moderate risk for Banks Peninsula! Cloud top temps to about -24C at this stage. More cooling aloft to occur yet. Its not a simple business!!

Paul

Manukau heads obs · Sat 16/09/2006 14:44

yeah, i figured out they were alot further away than they were plotting
and i did wonder if you were getting some deflection foggy

i am still learning about the boltec
its a neat peice of equipment!

03Stormchaser · Unread post by **03Stormchaser** » Sat 16/09/2006 15:08

A bit of Cu has gone up south of Bp. Nothing thundery about it yet, but will keep an eye on it. looks like its producing localised heavy shower.

tich · Unread post by **tich** » Sat 16/09/2006 17:10

Showers spread from the west on Banks Peninsula from about 2.30pm, but nothing thundery that I've noticed. Seems to have cleared up with only scattered clouds about, since the wind has turned to a fresh cooler southerly/southwesterly within the last hour.

NZstorm · Unread post by **NZstorm** » Sat 16/09/2006 17:56

Something I noticed about todays front was that the air was not just dry ahead of it but quite dry behind it as well. So despite some cold upper air there was little convective energy available today with the front, both in the west and the east.

Quite a cold day in Auckland today with 7/8 stratocumulus.

tich · Unread post by **tich** » Sat 16/09/2006 19:14

There must be some very cold air to the south of NZ - Campbell Island was only 0C at 3pm and -1C at 6pm. The weather has cleared on Banks Peninsula, and the 6pm radar shows precipitation now well offshore.

03Stormchaser · Unread post by **03Stormchaser** » Sat 16/09/2006 19:14

Even the upper air today I dont think was really cold enough. During summer possibly but with a gusty NW before hand, doesnt ever help.

NZ Thunderstorm Soc · Sat 16/09/2006 20:05

some pix from today taken from West Melton and Beckenham

JohnGaul
NZTS