NZ Weather Forum

The cold outbreak next week looks active on the GFS with a decent jet stream coming up. Something to keep an eye on.

Models going for 30-40cm above 300m in Canterbury and lesser amounts down to 100m, could be the one snow enthusiasts have been waiting for all year for central Canterbury around the 200-300m asl mark...

where are the models you look at bradley?

http://www.weatherzone.co.nz/models/?lt ... t&focus=mc

Then switch to rainfall option at the top, add up the precipation amounts from when there is at least -4C at 850hpa (minimum temperature needed for snow at 200m-300m asl) and you get between 30-40mm of precipation which of course translates into 30-40cm of snow at this altitude...those kind of calculations worked perfectly well for the June and July's cold snaps for this part of the world...of course the models can change wildly in between now and then!!

The models have snow switched back to a more modest 10cm for snowfall now, they'll keep giving varying right up to the event...

thickness has dropped a little to 522 which is low enough for sea level snow

We are getting showers at the moment. This was not in the forecast.

jamie wrote:We are getting showers at the moment. This was not in the forecast.

gfs showed some weak showers Waikato north for this afternoon. But dry here with 17C max.

Looks like a huge cold airmass for wed/thur

NZstorm wrote:

jamie wrote:We are getting showers at the moment. This was not in the forecast.

gfs showed some weak showers Waikato north for this afternoon. But dry here with 17C max.

I hadnt been looking at the models, but Metservice definitly didnt have it in the forecast for us. While it first started raining i looked on my phone and it said "fine"

September is going to be quite up and down, typical of spring with warm weather after tomorrows cold front and then another cold front around the 15th. Alot more interesting for us weather watchers than the previous month

Warmer air comes back onto the South Island fairly quickly on Thursday. 12Z GFS chart for Thursday shows 850mb -4 over Gisborne and +7 over Otago!

Looks like more of a spring westerly pattern for next week or two. GFS 7 day rainfall chart certainly highlights that.

Dewpoint has dropped down to 3C here this evening - tomorrow morning could be the coldest it's been for at least a month I would say.

David wrote:Dewpoint has dropped down to 3C here this evening - tomorrow morning could be the coldest it's been for at least a month I would say.

Down to 3.7C here earlier but could have got 1 or 2C if the southerly had fully died out

Looks like a beautiful morning!

I see a warm front develops in the central Tasman and spreads onto the upper North Island from later tomorrow. Dewpoints of 13-15C with this front.

Huge thunderstorm here at Mt Cook last night. Has broken to a stunning dawn though

Heavy showers here atm, looks like its trough associated.

Sadly, not making it past the Kaimai Force Field that protects Tauranga from such Westerly weather (and most lightning).

Second day in a row the weak SW wind changes have come within a few k's but the NW wind kept it nearer to the coast

A trough crossing the upper North Island overnight with an associated thunder risk. (see lightning tracker, storms in the Tasman!) Auckland north by the looks.

And another upper trough crossing the North Island tomorrow afternoon with cold air. Unfortunately it maybe a bit too hopefully to expect a dry game at Eden Park. Cold SW wind as well.

Been a great month so far bar tomorrow with the SW just for Auckland area.

Just started raining here. Looks like we could be in for a bit of a decent dollop.

Quite cold air with that trough this afternoon for Auckland. Hail likely with the heavier showers. Maybe isolated lightning strikes given 500mb temps -28C.

Yea I'm looking forward to some hail. Hopefully it comes this way and not too far north.

Had another 16mm overnight. Now up to 109mm for the month already.