Cold Snap 18-22 September 2015

[David]

Looking like the gfs and European can't agree on the evolution of the low pressure system over the north of the country Sunday/Monday. Looking like the subtropical jet will interact with the polar trough so some development definitely on the cards.

GFS seems to be coming more into line with European model now.

[NZstorm]

Looking like a borderline set up for thunder in the east of the South Island Friday on a southerly buster and also upper North Island Friday as a small 500mb trough crosses. I can't see anything happening tomorrow though.

[03Stormchaser]

Yeah I can't see a lot happening here. The very cold air is arriving too late, will make for an inside weekend I think.

[NZstorm]

Yeah I can't see a lot happening here. The very cold air is arriving too late, will make for an inside weekend I think.

500mb temp on southerly buster tomorrow afternoon -26C. Slight potential there.

[Richard]

Yeah I can't see a lot happening here. The very cold air is arriving too late, will make for an inside weekend I think.

Maybe a late arrival but there have been times in the past where thunder and lightning has accompanied a cold front during darkness hours, so its not out of the question i think. Also there appears that a tough will move NE on that front, so that might help with some extra stability enhancement.

[NZstorm]

Yeah I can't see a lot happening here. The very cold air is arriving too late, will make for an inside weekend I think.

Maybe a late arrival but there have been times in the past where thunder and lightning has accompanied a cold front during darkness hours, so its not out of the question i think. Also there appears that a tough will move NE on that front, so that might help with some extra stability enhancement.

The southerly buster according to gfs reaches Timaru by 3pm.

As for the Auckland, we may get rumble off the morning front tomorrow. 500mb-22C surface dp13C.

[spwill]

I think for thunder to occur in Canterbury tomorrow daytime heating will be a factor , it's not overly cold in the upper levels or overly moist at low levels

[RichyDunedin]

Good setup for storms here today. Currently on 22 degrees and no cloud cover.

[Bradley]

For once EC is going for big falls in mid-Canterbury over the next week whereas GFS is only going for around half the amount, 15-20mm. Very unusual to see that will be interesting to see how it pans out...

[Richard]

Yes its stating to look like we may finally get some useful rain next week though the models have been a bit inconsistent over the last two days, looking more likely to North Canterbury than further south.

[melja]

Can't see much happening next week, looks mostly dry and cooler

[Storm Struck]

Hmm a dry southerly has come through already with low cloud scittering in from the south, Im not sure if its a good thing as to whether the southerly sticks around or dies away to allow a NE to kick in.
Theres no moisture until 3pm onwards so I cant see it lasting, but it does boot out the NW by adjusting the flow and becoming more favourable for storms later on.

[matttbs]

Met service have issued a watch for heavy snow for Canterbury south of Rakaia river and a warning for north of it - 20-30cm above 400m with lighter snow to 200m from tomorrow

[dogmelon]

These innocuous little dry southerly changes that come through are curious. I wonder why they happen, they seemingly just sneak up on you.

[Bradley]

It has now swung the other way with GFS going for 20-30mm for mid-Canterbury over the next 3 days while EC has downgraded massively to just 5-8mm - EC is usually right in these situations!

[RichyDunedin]

Had a huge downpour with very loud thunder here. Lightning hit just down the street here in South Dunedin. This was about 15 minutes ago and it was clear all day before that.

[Storm Struck]

I must say its looking like a decent set up now, the suns out 16c and a very light SE wind so its swinging around.

[Bradley]

I must say its looking like a decent set up now, the suns out 16c and a very light SE wind so its swinging around.

Yes this is starting too look like quite a decent cold front for September, I think this one might surprise a few people with how low the snow will go!

[matttbs]

I must say its looking like a decent set up now, the suns out 16c and a very light SE wind so its swinging around.

Yes this is starting too look like quite a decent cold front for September, I think this one might surprise a few people with how low the snow will go!

I'm hoping Mt Peel will work its magic and produce a decent storm. Going by radar that southerly is coming up very fast

[Orion]

I can see some cloud far on my southern horizon.
I'm having broadband issues, so can't easily access rain-radar today: I presume it's showing on there?

[matttbs]

I can see some cloud far on my southern horizon.
I'm having broadband issues, so can't easily access rain-radar today: I presume it's showing on there?

Yea it's working it's way up Otago at present. At its current rate I would say there is a very good chance of it arriving while there is still some good heating so here's hoping for the first decent TS of the season!!

[Richard]

Still a NW blowing here, all eye's to the south hey

[Razor]

Have split out a new thread for this weekends cold snap and moved some relevant posts over. Looks significant enough to warrant its own thread for future reference now

[Razor]

I can see some cloud far on my southern horizon.
I'm having broadband issues, so can't easily access rain-radar today: I presume it's showing on there?

Yea it's working it's way up Otago at present. At its current rate I would say there is a very good chance of it arriving while there is still some good heating so here's hoping for the first decent TS of the season!!

Be the second decent TS for us if one eventuates

[Storm Struck]

The area to the west of Ashburton coming out from mt peel is one to watch, it looks like theres been storms from Oamaru slightly northwards.
This southerly is running into a fresh breezy NE here at the moment so once it moves up the plains should ramp it up.
Christchurch could well be the best spot