Complex low pressure system & cold outbreak 3rd-8th August

[SnwAddct]

850hpa temps of -4 for Auckland over the weekend, could provide some interesting scenarios..

[spwill]

A decent southerly storm for the east of the North Island on Saturday.

[spwill]

850hpa temps of -4 for Auckland over the weekend, could provide some interesting scenarios..

Stable conditions though. EC has it warmer around 0C

[Storm Struck]

This mornings run of EC has halved the moisture levels again for coastal Canterbury and most inland areas too, this looks to be one of those systems which is winding back the closer we get to the event which I guess is pretty consistent with every promising weather system this winter to date

Still a very significant outbreak none the less and probably good that huge totals dont eventuate inland right before lambing, however the latter part of the week overnight Thursday into Friday now plots abit more moisture.
So should be a relatively good dusting for those at sea level too, the MS 3 day rain maps now show purple gradiant over the coastline which you don't often see.
Hoping it holds true be nice to get some action weather for once.

[mikestormchaser]

Fri night sea level snow for East of South island. If moisture there that's when the southerly opens up the freezer door.

[Bradley]

I see Metservice now has possible snow in it's forecast for Christchurch on Friday and Saturday, even though the moisture levels have gone right down in last 24 hours we could still get 2-5cm of the white stuff in Christchurch in that time which would be an awesome sight

[Razor]

Both a Warning and a wider longer term Watch now in place on the Metservice. For future reference...

SEVERE WEATHER WARNING.

ISSUED BY MetService AT 11:13 am 02-Aug-2016

Heavy snow for inland parts of Southland, Otago and South Canterbury during Wednesday, with further snow during Thursday and Friday.

A complex low pressure system is expected to move onto the country from the south Tasman Sea during Wednesday, then move slowly northeastwards across New Zealand during Thursday and Friday, bringing rain to many parts of the country, with snow lowering to low levels about the east of the South Island.

The heaviest snow is likely about inland parts of Southland, Otago and South Canterbury south of Fairlie during Wednesday, with 20 to 30cm expected above 400 metres.

Heavy snow can cause major distruption to transport as well as significant stress to livestock and could cause power disruption. Blizzard conditions are also likely in exposed areas.

Note, further snow is likely in these areas during Thursday and Friday, and extends over remaining inland parts of Canterbury, possibly to near sea level.

HEAVY SNOW WARNING

AREA/S AFFECTED
Inland parts on Southland and Clutha.
FORECAST

Rain is expected to turn to snow above 200 metres Wednesday morning. In the 12 hours from 6am to 6pm Wednesday, expect 15 to 25cm to accumulate above 400 metres, with 5 to 10cm possible down to 200 metres.

FREEZING LEVEL: Lowering to 600 metres Wednesday morning.

AREA/S AFFECTED
Otago and inland parts of South Canterbury south of Fairlie, including the Mackenzie Basin.
FORECAST

Rain is expected to turn to snow above 200 metres Wednesday morning. In the 18 hours from 6am to midnight Wednesday, expect 20 to 30cm to accumulate above 400 metres, with 5 to 10cm down to 200 metres. Heavy snow is expected to ease about Central Otago late Wednesday afternoon, but continue in eastern Otago and south Canterbury through to midnight Wednesday.

Note, a Watch for possible heavy snow to 400 metres is in place for eastern Otago Thursday morning and to low levels for South Canterbury during Thursday and Friday.

FREEZING LEVEL: Lowering to 600 metres Wednesday morning.

NEXT SEVERE WEATHER WARNING WILL BE ISSUED AT OR BEFORE 9:00 pm Tuesday 02-Aug-2016



SEVERE WEATHER WATCH FOR TARARUA, KAPITI HOROWHENUA, WAIRARAPA,WELLINGTON, BULLER, DUNEDIN, NORTH OTAGO, CHRISTCHURCH, CANTERBURYPLAINS ISSUED BY METSERVICE AT 1040hrs 02-Aug-2016

BURST OF HEAVY RAIN FOR BULLER AND TARARUA RANGE WEDNESDAY. HEAVY SNOW ABOUT EASTERN PARTS OF THE SOUTH ISLAND THURSDAY AND FRIDAY.

A complex low pressure system is expected to move onto the country from the south Tasman Sea during Wednesday, then move slowly northeastwards across New Zealand during Thursday and Friday,bringing rain to many parts of the country, with snow lowering to low levels about the east of the South Island. A Warning for Heavy Snow is now in place for inland parts of Southland, Otago and inland South Canterbury south of Fairlie.

This Watch is for the possibility of rainfall accumulation reaching short-duration warning amounts (70 to 90mm in 12 to 18 hours) in the ranges of BULLER during Wednesday morning and for the TARARUA RANGE Wednesday morning and afternoon.

Additionally, this Watch is also for the possibility that further significant snow is possible about DUNEDIN and NORTH OTAGO Thursday morning and that snow accumulations could approach warning amounts to low levels in CANTERBURY and the KAIKOURA COAST on Thursday and Friday.

People in all these area should keep up to date with the latest forecasts, as parts of this Watch may be upgraded to a full warning, and further areas could be added.

This Watch will be reviewed by 10pm Tuesday 2 August 2016

[mikestormchaser]

I see Metservice now has possible snow in it's forecast for Christchurch on Friday and Saturday, even though the moisture levels have gone right down in last 24 hours we could still get 2-5cm of the white stuff in Christchurch in that time which would be an awesome sight

What's wrong with the moisture levels for Thursday night into fri? Decent for my liking

[matttbs]

I see Metservice now has possible snow in it's forecast for Christchurch on Friday and Saturday, even though the moisture levels have gone right down in last 24 hours we could still get 2-5cm of the white stuff in Christchurch in that time which would be an awesome sight

What's wrong with the moisture levels for Thursday night into fri? Decent for my liking

Agreed, still looks great to me

[Bradley]

EC has 3mm for Christchurch for the Thursday-Friday period, GFS is in fantasy land if it reckons Christchurch will get 25-30mm on those 2 days! GFS always seem to over exaggerate moisture levels leading up to events like these...

[matttbs]

EC has 3mm for Christchurch for the Thursday-Friday period, GFS is in fantasy land if it reckons Christchurch will get 25-30mm on those 2 days! GFS always seem to over exaggerate moisture levels leading up to events like these...

Good thing I don't care what Christchurch is getting as I'm not there haha. Sounds like you have already given up on this event. You never know, gfs could be right on the money for this one

[SnwAddct]

GFS data for Mt Hutt for the days Thursday - Monday, some big totals being suggested..

Capture.JPG

EC data for Mt Hutt provided by yr.no does seem to of backed right off for this event..

Capture1.JPG

[Bradley]

EC has 3mm for Christchurch for the Thursday-Friday period, GFS is in fantasy land if it reckons Christchurch will get 25-30mm on those 2 days! GFS always seem to over exaggerate moisture levels leading up to events like these...

Good thing I don't care what Christchurch is getting as I'm not there haha. Sounds like you have already given up on this event. You never know, gfs could be right on the money for this one

Haha yeah true, Mayfield still looking good though for 20-30cm, I've only given up on decent snowfall for Christchutch, inland areas above 200m should still do quite well! Here's Tony's latest forecast which backs up the lack of any decent accumulations under 200m:


Snow Forecast for Canterbury High Country and Plains:
A low pressure system is developing in the eastern Tasman Sea and will move across central New Zealand tomorrow. This will bring an easterly airflow onto Canterbury in already cold air, and the air will become even colder on Thursday as it swings southeast. Further pulses of cold air will arrive on Friday and Saturday, as an anticyclone develops in the south Tasman Sea.

Light snow falls should stay above 500m tomorrow, with accumulations of 3-5cm above 500m. Steady falls will lower on Thursday and Friday, with 5-10cm expected on each day, above 400m on Thursday but lowering late in the day, and down to 200m on Friday. A further 5-10cm is expected on Saturday above 200m, and some lighter falls under 200m on the Plains. Overall, accumulations from Wednesday to Saturday may reach 20-30cm above 400m, and 10-20cm above 200m. Later on Saturday a clearance is expected in South Canterbury, spreading to Mid Canterbury by early Sunday. At this stage, no periods of strong winds are expected in the Wednesday to Saturday timeframe but air temperatures will be very cold.

[hozza95]

Bit strange that metservice don't have a weather watch out for snow out for inland Southland on Thursday, since in their latest outlook they have a ' moderate ' confidence of heavy snow to low levels, I guess they will add it to the watch tonight

[snowchaser01]

Latest Severe Weather Outlook from Metservice here.

Issued: 3:17pm Tuesday 2 Aug 2016
Valid from Thursday 4 August 2016 to Sunday 7 August 2016

A complex low pressure system over the South Island moves slowly northeastwards over the country from Thursday to early Saturday, bringing rain to northern New Zealand and snow to east of the South Island.

There is moderate confidence of snow reaching warning amounts to low levels in inland Southland and Otago on Thursday. There is moderate confidence of snow reaching warning amounts to low levels in Canterbury and the Kaikoura Coast during Thursday and Friday.

Further north, there is low confidence that rainfall amounts reaching warning amounts in Wairarapa during Friday and Saturday, and moderate confidence in Hawkes Bay and Gisborne from Friday to early Sunday. There is also a low risk of heavy snow about Tongariro National Park and Taihape above 700 metres during Friday and Saturday.

In addition, east to southeasterly winds are expected to become strong for the lower and central parts of the North Island during Friday and Saturday.

[mikestormchaser]

EC has 3mm for Christchurch for the Thursday-Friday period, GFS is in fantasy land if it reckons Christchurch will get 25-30mm on those 2 days! GFS always seem to over exaggerate moisture levels leading up to events like these...

Good thing I don't care what Christchurch is getting as I'm not there haha. Sounds like you have already given up on this event. You never know, gfs could be right on the money for this one

I'm in rolleston Matt so bit more open on the Plains then Christchurch to. Tends to get more precipitation out here. Quite a change in weather pattern from about Templeton south

[Bradley]

Latest EC run is much the same as this mornings, around 10-12mm of rain for the total event (wed-sat) for Christchurch and perhaps 1-2cm of snow on Friday whereas inland area like Sheffield at 300m asl is showing around 15-20cm, certainly going to be almost exclusively an inland event this one!

[snowchaser01]

Latest EC run is much the same as this mornings, around 10-12mm of rain for the total event (wed-sat) for Christchurch and perhaps 1-2cm of snow on Friday whereas inland area like Sheffield at 300m asl is showing around 15-20cm, certainly going to be almost exclusively an inland event this one!

What sort of history does EC have with these events? GFS showing a lot more than 10-12mm for whole event, and from what I remember, they seem to be quite good..

[Razor]

Latest EC run is much the same as this mornings, around 10-12mm of rain for the total event (wed-sat) for Christchurch and perhaps 1-2cm of snow on Friday whereas inland area like Sheffield at 300m asl is showing around 15-20cm, certainly going to be almost exclusively an inland event this one!

In past years I recall much post-event analysis concluding not to put too much credence on the detail in the models. Look at the bigger picture, I feel this is going to be really disruptive

[matttbs]

Yes i think this is going to be alot bigger then what EC is saying, don't put all your faith in the one model. Metservice's 3 day rain map is certainly showing alot more then 10mm

[Richard]

I think you are going to be right Razor as GFS are still going with 80mm of precipitation or more north of Christchurch, if most of that falls as snow

[Talbotm]

Interesting talk down by Georgina Griffiths from the Met Service. http://www.stuff.co.nz/national/8271512 ... rom-tasman

[Bradley]

Interesting talk down by Georgina Griffiths from the Met Service. http://www.stuff.co.nz/national/8271512 ... rom-tasman

Yeah she kinda puts this system into perspective but hey, it's still 10 times better then any system we've had this winter so far!!

[snowchaser01]

Interesting talk down by Georgina Griffiths from the Met Service. http://www.stuff.co.nz/national/8271512 ... rom-tasman

Yeah she kinda puts this system into perspective but hey, it's still 10 times better then any system we've had this winter so far!!

She states it is an unusual event.. it looks to be better than anything we have had for at least 2 years!

[matttbs]

Not sure if it's going to be as big a snowfall as last year, that produced just under 40cm for us here but in terms of snow level it's looking like the lowest for a while