NZ Weather Forum

Yep neat photo alright.

Thick heavy fog here this morning which has helped keep the frost away.

Now that this event is mostly over in terms of snow fall, we can start talking about late next week, which has been in the models for a few days now. A possible advection element in there too. Could be interesting for sure.

Yes, could be. Have to wait to see how the models pan out for this

GFS likes it more then EC at this stage - a good sign as EC so far this winter has been performing badly compared to past seasons!

Bradley wrote:GFS likes it more then EC at this stage - a good sign as EC so far this winter has been performing badly compared to past seasons!

Agree...Metvuw (GFS) very accurate for this region all year

Good.

Yes, GFS has been looking promising next week for some for a few days now. Time will tell, lets see what it looks like come Monday

I'm not 100% sure on the numbers for warm advection events but it looks quite warm. I know warm advection is different and the models dont pick it all up. But it still does look warm this far out

mikestormchaser wrote:I'm not 100% sure on the numbers for warm advection events but it looks quite warm. I know warm advection is different and the models dont pick it all up. But it still does look warm this far out

Things like thickness and the upper temps don't really hold much value when it comes to advection. Its all about cold air undercutting warmer air, and the heavy precip that the warm air brings lowers the freezing level.

I think with the warm advection low level snow ( approaching north Tasman low) you still want to see at least quite cold air in the model, residue chilled air in the inland valleys helps a lot as well.

spwill wrote:I think with the warm advection low level snow ( approaching north Tasman low) you still want to see at least quite cold air in the model, residue chilled air in the inland valleys helps a lot as well.

The warm advection snow in Tekapo earlier this month had 850mb temperatures around 0C in the modelling and snow fell to 700m.
A big snow dump in Southland on 24th July last year occurred with 850mb temps -2 to -3C and snow fell to 100m. This gives a rough idea of what temperatures to look for in warm advection snow forecasting. And yes, a severe frost in the valleys helps.

Yes and the big one in Canterbury in June 2015 had 40cm of snow to 300m ask and 10cm right down to 150m with 850hpa temps of only -2C

Definately something big and nasty brewing for Thursday next week - knowing the unpredictability of these low pressure systems though it could just as easily end up hitting the North Island instead

GFS has backed off big time this morning. If only we could get just one decent saturating weather system.

Currently cloudy and -1.6°C.
Decent frost, with low of -2.5°C but it clouded over quite quickly now so could be a rather miserable day.

It's actually started drizzling and it's still -1.6°C.
Went outside to get some wood and yeah, got a little bit wet and still well below zero.
Not sure I've ever experienced that before.

Bradley wrote:Definately something big and nasty brewing for Thursday next week - knowing the unpredictability of these low pressure systems though it could just as easily end up hitting the North Island instead

Yes, another cold southerly blast seems locked in, but only brief, and not as cold as the last one.

Looks interesting Thursday/ Friday!

Considerable uncertainty I know, but if this comes off...it'll be an interesting end to the school hols

Yes a couple of key elements of this event such as precipitation, 850hpa temps and thickness levels remind me of the 12th June 2006 event, if anything this could be even nastier! As we know though the position of these low pressure systems are notoriously hard to predict. For reference below is the meteogram from the night before the 2006 event and also the latest meteogram for Friday:

Strong wind possible with the system late week.
Currently the gfs is going for severe gales in exposed areas for the North Island with Thursdays front. Auckland area could see big gusts.
And severe gales for eastern South Island Friday. Just model output at this stage and not a forecast.

I'd like to know where tomorrow's heavy rain is coming from tomorrow?
Over 20mm for Timaru forecasted.
Looks like a forecast for Hamilton or Auckland.

Mt Cook Village has been awfully cold so far this month. Average high of 3C and an average low of -7C (July normals are 6.5C/-2C). July 7th was the coldest day, at -3C/-12C (though yesterday was close, at -2C/12C).

Plato wrote:Mt Cook Village has been awfully cold so far this month. Average high of 3C and an average low of -7C (July normals are 6.5C/-2C). July 7th was the coldest day, at -3C/-12C (though yesterday was close, at -2C/12C).

The higher parts of the Mackenzie can be bitter in Winter including Tekapo and Twizel.

NZ Thunderstorm Soc wrote:I'd like to know where tomorrow's heavy rain is coming from tomorrow?
Over 20mm for Timaru forecasted.
Looks like a forecast for Hamilton or Auckland.

Coming down heavy here near Pleasant point for the last couple of hours, 10mm in the gauge. if it keeps up for another couple of hours wont be far off the 20mm forecast.

Yes, interesting. Been raining here since this morning from the north.
Looks dark towards the Point but is clearing to the north. 4.3mm so far here for today.