Canterbury thunderstorms - 15 November, Chase and reports

[Storm Struck]

It sure is a great day out there again, however its taking forever for those warm temperatures to arrive this year.
A moderate risk still exists today for thunderstorms south of Banks Peninnsula, but more around the penninsula area than the coast.
It does say about those coastal NE winds getting up between Rakaia and BP, but its coastal NE here also at the moment with some scrappy weak CU from the cold front crossing.
Is it wishful thinking for a chase this afternoon .

[NZ Thunderstorm Soc]

Not a very interesting day here, scattered cloud and winds between west and SW.
We must have lowcentre over us or nearby?

JohnGaul
NZThS

[Storm Struck]

W-SW its NE here John , it might be that cold front just sitting over us.

[CHCH Weather Chaser]

Yes light WSW as the prevailing wind here as well. Variable however as now NNW. High cloud around at the moment. Got to 21 down to 19.6 at the moment,

[dogmelon]

Calling Paul Mallinson. It would be most interesting to hear from Paul as to whats happening or some such.

[Storm Struck]

CU building to the west and SW from here, wind definatly still NE and picking up abit too.

[NZstorm]

According to the gfs an upper trough currently over Dunedin will strengthen and reach Christchurch late afternoon/early evening. So upper level support is there for convection, the question mark is over surface convergence/moisture. But you would have to go with some convection firing. All very coastal though.

[mikestormchaser]

Aaron, Jase steve?? ANDREW? Leighton?? should we prepare for a chase this afternoon then??

[NZstorm]

You have a big westerly upstairs down there so any cb development will move quickly out to sea.

[NZ Thunderstorm Soc]

Looking clear and fine to the south, now. The barometer is still going down. All we need is the NE to kick in for something to happen, possibly on a convergence line sort of thing.

JohnGaul
NZThS

[Paul Mallinson]

According to the gfs an upper trough currently over Dunedin will strengthen and reach Christchurch late afternoon/early evening. So upper level support is there for convection, the question mark is over surface convergence/moisture. But you would have to go with some convection firing. All very coastal though.

\
NZstorm has hit the nail on the head. We have a cold trough moving over the lower half of the South Island this afternoon and temps will fall to about -26C at 500 hPa over the CHCH area and colder further south. We already have an onshore east to northeast flow into Canterbury and Otago and this has brought in the elevated dewpoints (in the 6-10C range). Strong drier westerlies are located inland. It is a question of the convergence and moisture about the coast being sufficientto trigger thunderstorms. If they do occur, the main threat will be hail. It looks like a dry westerly will push out to the coast in the Timaru/South Canterbury area in the next few hours, but the convergence remains in the Banks Peninsula and eastern Otago areas until early evening.

It will be an interesting afternoon.

Paul

[Storm Struck]

It looks like a few showers have popped up over North Otago now, so there must be abit of development down that way near the westerly which isnt bad.
I would say if anything does develope it will be around 3-7pm, so its all eyes on the sky until then.

[mikestormchaser]

Well take a look out there now, Nice bit of CU build up over my way and over BP and the clouds are wild there swirling in al directions!! very unstable

[Andrew Massie]

I'm currently taking timelapse of CUs going up over Banks Peninsula.. Stole that idea from Lacertae! Be interesting to see how they come out...

It is looking unstable out there.

[Storm Struck]

Not looking too bad out there now lots of CU building up nicly to the SW from here, also some overhead and slightly west.
You can see where the easterly meets westerly inland, also some low level stuff coming in from the east.
Much more keen Easterly now, getting close to heading out.
Edit: 2:50pm and we have ignition some strikes on the trackers now.

[NZ Thunderstorm Soc]

Finally back to a light NE here, well since ten to three
Remaining fine and clear to the south. Barometer still dropping.
Was some CU about but all seem to be weak and dissipating.
JohnGaul
NZThS

[Thunder]

Strikes seem to be off the Otago coast so a bit to far away.

Here's hoping for something, I haven't looked into anything to much....

Cheers
Aaron

[NZ Thunderstorm Soc]

Back to SW here, sadly

JohnGaul
NZThS

[Michael]

Back to SW here, sadly

JohnGaul
NZThS

You can keep em down there

[CHCH Weather Chaser]

ENE here and has been for last hour or so. Around 20km/h , definately W up high as clouds show this. Big blow up dark and unstable clouds overhead at the moment. Came from no where, plenty of Blue sky to the south just a big line of dark clouds overhanging from W to E. 19 degrees.

[03Stormchaser]

Current convergence line south of CHC, positive sign for things to come.

[mikestormchaser]

Not a bad DP we sitting on either 10.1 according to jeffs.
That CU looked really weak and the air looks very dry i think that due to the westerly unfortunately
In my opinion i dont think much will fire up and if it does you might need to take a quite a drive to the other side of the BP if not catch a boat

But i hope things do fire up and i am completly and utterly WRONG!
Do let me know Aaron or steve if you guys think its worth heading out and i should come meet up with you guys

[NZ Thunderstorm Soc]

I like the "H" on MetServices 1pm surface chart, just out from BP on the tailend of today's cold front.
I wouldn't call 993 hPa as high pressure
JohnGaul
NZThS

[Myself]

It doesn't matter....a high is a high.

[NZ Thunderstorm Soc]

....or higher? higher air pressure than the air surrounding it.

Back to NW now here at the moment and all clouding seems to be dissipating.

JohnGaul
NZThS