Cold outbreak October 10th-12th

[Chris W]

I think this deserves a thread, much of the country is in for some mix of heavy rain, snow and strong wind from tomorrow through Friday. My reading of the latest 3-day MetService rain charts are that moisture has been upgraded for mid and north Canterbury as the Tasman low and two fronts coalesce.

Currently the snow level is forecast to be down to 400m in Canterbury and down to 200m in Fiordland, largely on Friday as the second southerly arrives and meets a shortwave working its way around the main Tasman low.

[NZ Thunderstorm Soc]

Judging from the last 2 cold outbreak warning scenarios and with global warming /climate change, probably nothing really except in Southland/South Otago and possibly in inland areas further north.
Looking at Mt. Peel today, whilst gathering some firewood in anticipation of the coming cold snap, I thought of and wondered and said to myself, would there much more snow up there on Saturday from this upcoming cold weather event?
There has been not much snow along the foothill peaks so far this winter.

[03Stormchaser]

Last couple of runs have increased rainfall for Canterbury and the west coast. Leading up to the previous couple of cold events, models have reduced rainfall as we got closer. Still Friday is a long way out.

GFS raincast forecast as reference

Screenshot.JPG

[NZstorm]

Snowing in western Southland. TeAnau Airport has 0C with snow. Elevation around 200m.

Midday Invercargill observed sounding looking like the classic warm advection snow set up.

[tich]

Still warm (21C) in Chch with gusty northwesterly.

[talbotmj15]

MetService latest Outlook looks interesting.

Severe Weather Outlook
Issued: 3:34pm Wednesday 10 Oct 2018
Valid from Friday 12 October 2018 to Monday 15 October 2018

A cold southerly outbreak affects New Zealand this week

Severe Warnings, Watches and Road-snow Warnings are already in force for parts of the South Island for this event. Please keep up to date with the latest forecasts and Warnings for your area as other places are likely to be added as the event unfolds.

On Friday, an active front and associated low are forecast to track east across central and northern New Zealand, preceded by strong and moist northerlies. Ahead of these features, there is low confidence that warning amounts of northerly rain will accumulate about Mount Taranaki, the Whanganui headwaters, Tongariro National Park, and eastern Bay of Plenty.

As the front and low move away to the east on Friday, the strong and cold south to southeasterly flow should spread across the country. During this time, there is high confidence of snow amounts reaching warning criteria about inland Canterbury and Marlborough above 300 metres, while the confidence is low for inland parts of Otago, Southland and Fiordland above 200 metres. There is also low confidence of warning amounts of snow falling above 600 metres about the central North Island High Country, including the ranges of Hawkes Bay about the Wairoa District on Friday and into Saturday. Higher roads, passes and farms in these areas are likely to be affected.

In addition, strong to gale force south to southeasterly winds are likely in many places, with moderate confidence of becoming severe in exposed parts of Wellington and coastal Marlborough, low confidence for the remainder of the lower North Island from Taranaki to Bay of Plenty, southwards, and low confidence in the remainder of Marlborough, also Nelson and northern Westland.

From late Saturday and during Sunday, the southerly flow across the country is forecast to ease as a ridge of high pressure over the Tasman Sea slowly drifts onto the country and becomes slow moving.

[NZ Thunderstorm Soc]

Southerly through here at 3pm. A bit disappointing, lots of wind and a quick cover of stratus and a temperature drop. Down from 21.6C to 13C in about half and hour.

[NZstorm]

Pukaki Airport (Twizel) upto 21C today. Quite warm considering the wintry forecast for the region tonight.

[Andy]

3.8 at Queenstown airport

[NZ Thunderstorm Soc]

Snowing in Southland. Looks like a similar event to the one, 2 events ago.
Interesting to see how the rest of this weeks pans out

[Storm Struck]

Ive been watching the models on this years winter systems the ones that came and went without too much to show.
This one has caught my attention, more so for the cold stinger in its tail on Friday.
Moisture is lining up and has been favourable for quite some days now, and our windflows are where we want them to be.
More importantly are the 2m temperature projections overnight friday combined with windchill and Canterburys coldest 850mb temp this year of -7C and -8C sliding along the coast.
Other factors are warm and yes it is mid spring, but im seeing a window Saturday morning 1am to 7am for wintry showers sleet hail and snow bordering below 100m so you could almost say to near sea level.
Its a shot in the dark given this years weather outcomes and given its mid spring etc, but its worth noting.
One thing for sure there will be snow on the port hills.

[melja]

Not a drop of rain in Rangiora so far, another non event?

Sent from my Redmi Note 4 using Tapatalk

[Richard]

A good example of how TV weather reports do so much damage within the general public's perception of weather forecasts and forecasters. I was at a meeting last night, and after the meeting during general chit chat there was talk around the room that 'where was that rain they said was coming today, there are bloody useless etc etc ', i said "who said it was going to rain today? "oh they were saying that on TV last night". .....[expletive deleted], any rain wasn't due till around midnight yet TV3 had rain for the afternoon.

[melja]

Torrent of drizzle in chch

Sent from my Redmi Note 4 using Tapatalk

[NZstorm]

I agree with storm struck, snow could fall to 100m in Canterbury tomorrow. Plenty of precip in the modelling in the morning.

[mikestormchaser]

As much as I'd love it to snow, I think we will just see sleet showers to ground level tomorrow. And snow down to 200m at its lowest.
But who knows.. looks cold on the models for sure I just think being mid spring, it may not get as cold as the models are suggesting.
Good moisture though and a nice southerly air flow so will be good for inland areas and ski fields just when there looking at closing up for the season

[snowykiwi]

Severe Weather warning now out from the Metservice. Will be interesting to see how much snow Methven receives during tomorrow.

[Chris W]

Also a severe gale warning for the Kaikõura coast, currently I am in Kaikõura where the cloud base against the mountains is about 100m! Back to Chch tonight.

Tomorrow was always looking like the main event from mid Canterbury northwards. Saturday morning looks chilly as well.

[Richard]

Wasnt expecting to have the sun out which it is at present

[snowchaser01]

As with most of these events that have advection elements to them, there is a lot of guess work. Everyone has their own opinions I guess, but certainly an interesting 24-36 hours coming up.

[Razor]

Banks Peninsula doing its sheltering effect for chch . Pretty benign event so far for us, be interested to hear reports further afield looking at the radar

[melja]

I hear all roads are clear ATM.

Sent from my Redmi Note 4 using Tapatalk

[Orion]

Raining and windy in Ashburton, trees & shrubs tossing.

[snowykiwi]

Raining and light winds in Methven, getting colder, but not cold enough for snow yet in my opinion.

[Rogue]

Atrocious driving conditions this morning on Wellington's motorways, a lot of surface water and very low visibility in places, surprised there haven't been more accidents