Polar Blast 23-26th July

[NZstorm]

Slightly off the SI topic here,

Wellington and Napier will get snow flurries from this system.

The very cold air makes it to Auckland Monday night with 850mbs temps -6C modeled by GFS atm.

[snowstormwatcher]

I see metservice are forcasting snow for Timaru and Oamaru Havent seen that for a while.

I Cant see much happening though, Sure the air is defenitly cold enough for snow to sea level but I cant see there being enough moisture. Id say there will be a few snow showers on the plains but most of that will be north of Ashburton.

[CHCH Weather Chaser]

I see metservice are forcasting snow for Timaru and Oamaru Havent seen that for a while.

I Cant see much happening though, Sure the air is defenitly cold enough for snow to sea level but I cant see there being enough moisture. Id say there will be a few snow showers on the plains but most of that will be north of Ashburton.

Agreed, I expect the snow watch for warnings will be lifted

[Lawrence]

Still a fair amount of moisture left,mainly in the afternoon for Canterbury lowlands.Might not get much.Have to wait and see now

[Razor]

I think a couple of you are failing to take into account our local coastal factors, which often make "drizzle" into more substantial precipitation.

Time will tell.

[CHCH Weather Chaser]

I think a couple of you are failing to take into account our local coastal factors, which often make "drizzle" into more substantial precipitation.

Time will tell.

Here's hoping! Although we need those isobars to turn more SSE than SSW. Tonights model run = crucial for me

[Storm Struck]

Again as i said last night the models will not pick up the affect these flows have, onshore flows increase precipitation levels.
Dont know what you mean by S-SW looks S-SE to me on the models, even so S-SW still brings activity onshore its the W-SW that pushed it offshore.
Its not going to be a huge snow potential but it will be enough to cover the grounds i believe.
Plus we have 2 systems colliding a low of sub tropical origion, and a cold trough from the south although its nowhere near 2006's situation advection can play a key role.

[CHCH Weather Chaser]

http://www.weatherwatch.co.nz/content/w ... ave-canada

Metvuw seems to have SSW more than SSE at the moment. ABove a link to weatherwatch video on this system coming. As they touch on SW will be all but dry for Canterbury but SE can bring the potential for heavy falls.

[dan]

According to this rain forecast by Metservice the snow could be falling to very low levels. And the North Island looks to get plenty of precipitation with snow maybe even on the Kaimais and Pirongia.

[Storm Struck]

Yeah that does make sense leighton, what i was more getting at was the situation we get when activity seems to deepen or increase as it hits land like weve seen in the past with S-SW flows.
I guess either way you win some and loose some, if its S-SE will there be a sheltering affect for parts of the city from the peninnsula? in some ways will be good bringing less to areas with damaged roofs etc.

[spwill]

Flow has been looking onshore for Canterbury Sunday, GFS, ECMWF.

[Richard]

The very cold southerlies are expected to bring snow to low levels to southern and eastern regions of the South Island during Sunday and Monday, with a high risk of significant amounts of heavy snow about North Canterbury, Marlborough and parts of Nelson.

For me this warning looks rather ominous where i am as its looking more of a CHCH northward event,boy its got my kids all excited though. me ,i,m more worried about my sheep and making sure they will be ok.

[Captain Salty]

in canterbury, are the eastern foothills likely to get the heaviest snow?

[Richard]

in canterbury, are the eastern foothills likely to get the heaviest snow?

Yes but its like whats was said in Leighton's link,a SW will do bugger all to the eastern areas, if its a straight Southerly,snow may well fall to sea level in the Pegasus bay area as a southerly will always swing slightly SW dragging the snow level to sea level (onshore wind).
If it's more SE, CHCH is sheltered to a small extent as Jase pointed out,but more importantly the wind becomes more offshore and offshore winds never bring snow to sea level because snow never falls on the oceans this far north.

[Lawrence]

Again as i said last night the models will not pick up the affect these flows have, onshore flows increase precipitation levels.
Dont know what you mean by S-SW looks S-SE to me on the models, even so S-SW still brings activity onshore its the W-SW that pushed it offshore.
Its not going to be a huge snow potential but it will be enough to cover the grounds i believe.
Plus we have 2 systems colliding a low of sub tropical origion, and a cold trough from the south although its nowhere near 2006's situation advection can play a key role.

Totally agree there.
Also I have never known it in my short time here not to snow when thickness is at 522.I am still fairly confident that the developement of that low is also something to watch closely tomorrow as it could change everthing, and we could end up with a fair amount of the white stuff

[Chris Raine]

Ah well, I am south of you in Oamaru so will let you know how events unfold tomorrow night as the southerly pushes through

[03Stormchaser]

Also I have never known it in my short time here not to snow when thickness is at 522

I'm currently looking at thickness levels down to 518 Sunday night, early Monday morning.
Nothing has changed for me in the last 2-3 days this is a snow situation to low levels for Canterbury. Every thing is lining up, cold air, precipitation, thickness levels and all at the right time, night when it will its coldest.

Snow is still very much still on the cards

[mikestormchaser]

Also I have never known it in my short time here not to snow when thickness is at 522

I'm currently looking at thickness levels down to 518 Sunday night, early Monday morning.
Nothing has changed for me in the last 2-3 days this is a snow situation to low levels for Canterbury. Every thing is lining up, cold air, precipitation, thickness levels and all at the right time, night when it will its coldest.

Snow is still very much still on the cards

EXELLENT!! come ooon mother nature give it to us this time !!

[03Stormchaser]

Metservice have the snow symbol out for chch for sunday aswell

Sunday 24 Jul
Snow

Max 5°C
MIN 1°C

Snow. Fresh cold southwesterlies.
Issued: 6:31pm 22 Jul

And under Darfields forecast for Sunday:

Snow lowering to sea level. Cold southerlies freshening.
Issued: 10:47pm 22 Jul

... the ducks are lining up!

[Lawrence]

Just a thought though, a Complex storm formation features two distinct low pressure systems;as to the north, one well inland and a developing coastal low.The thermal profile contains multiple above freezing layers which results in various precipitation types not only across the region but also in a specific location (depends on physical processes as well as precipitation rate.)
Sleet, snow, freezing rain or a wintry mix of all precipitation types are common.So the north Island might get some heavy stuff as well.

[snowstormwatcher]

Looking like it will snow here tommorow now as opposed to a couple of days ago where it was looking mainly like a north canterbury event.

[Lawrence]

Wind has been calm all night.Just starting to get a slight breeze from the South in the past hour.
http://www.wunderground.com/weatherstat ... ICANTERB70

[NZstorm]

The cold snap reaches Dunedin before dawn Sunday. GFS has a max temperature for Dunedin tomorrow of 4C!

[Orion]

At present: high light cloud moving across from the east. Wind on the ground westerly. Appears to be low cloud bank on horizon [within 8 - 15 miles?] from southeast through to northeast. 1.8 degrees, sunshine; 66% humidity.

[mattyj46]

AREA/S AFFECTED

Fiordland south of Manapori, Southland and eastern areas of Otago from Dunedin down to Clutha.
FORECAST

Snow is expected to lower to sea level overnight Saturday. For Fiordland south of Manapouri, Southland above 200 metres and Clutha expect 20 to 30 cm from midnight Saturday to midnight Sunday. While 5 to 15 cm could accumulate in remaining areas of Southland below 200m and Dunedin.

AREA/S AFFECTED

North Canterbury and Kaikoura.
FORECAST

Snow is expected to lower to about 300m on Sunday morning and to near sea level Sunday afternoon. From about 9am Sunday to midday Monday, expect 20 to 30 cm to accumulate above 300 metres, and 10 to 20 cm to lower levels.

http://www.metservice.com/national/warn ... r-warnings