South Island snow - July 6-10

[Bradley]

Latest run with EC has snow down to 100-200m next Tuesday/Wednesday, usually wouldn't mention it this far out but both GFS and ACCESS has exactly the same system with similar numbers as well.

[Razor]

Latest run with EC has snow down to 100-200m next Tuesday/Wednesday, usually wouldn't mention it this far out but both GFS and ACCESS has exactly the same system with similar numbers as well.

Where in particular? Looks like a hit and miss so far for here in Canterbury, models flipping a bit today

[Bradley]

Seems to be 2 polar opposite lots of model data at the moment between ACCESS which has a strong cold front and 15-20mm of rain on Tuesday and EC and GFS which has the cold front and good amount of precipitation non existent for Tuesday and instead has it for late Wednesday and Thursday. Usually I would just disregard ACCESS if EC and GFS were overruling it but it has been pretty consistent with the cold front arriving Tuesday the last number of runs.

[Bradley]

Interesting reading to say the least!

[Storm Struck]

http://www.metvuw.com/forecast/forecast ... si&tim=138
The low that crosses the top of the South island for early week could be some kind of advective event especially for North Canterbury, this map above shows it well although will probably change.

But yes definitely a cold week with snow potential there for a few days atleast.

[SnwAddct]

Wow weee next Tuesday night is looking cold! Potential sea level snow maybe?

[Bradley]

All models are in alignment now with this mornings run of EC showing sea-level snow from midday Tuesday right through to Thursday. Let's see if the same kind of data is still being projected in a few days time then maybe I might start getting excited!!

[Richard]

Looking at BOM map for Antarctica Monday it shows the wind flow off the central ice cap

[shovelopikis]

Looking at BOM map for Antarctica Monday it shows the wind flow off the central ice cap

Following that wee gap between pressures, it's streaming right from the geographical south pole?!

[Bradley]

Tony going all out for snow next week:

NOW FORECAST: We have increasing confidence of a potentially significant snow event affecting Canterbury next week. There have been indications in the models for several days now, and these indications are now aligned and consistent.A trough of low pressure will move over Canterbury about Tuesday next week, and be followed by a very cold south to southeast airflow next Wednesday and Thursday, easing next Friday. Pressures will remain high in an anticyclone over the far south of the country, and this anticyclone will direct the very cold air over Canterbury for several days.While it remains too early to attempt to precisely predict snow accumulations and locations, it does seem likely that falls of at least 30-50cm are possible above about 200m, and perhaps substantially more at higher levels, Falls are also likely to sea level, with a chance of 10-20cm accumulating over several days. The first low level snow should begin on Tuesday night with the heaviest falls currently indicated for next Wednesday and Thursday.We are still a long way ahead of this event, so forecasts may change over the next few days. However, the event currently indicated has the potential to significantly impact transport around the region, and cause serious issues for farmers with stock.

[03Stormchaser]

Whoa! Good to see Tony ahead of the game with this one, been watching it the last couple days. Seems pretty consistent in the models.

[Bradley]

I have to say I don’t what models Weather Watch were looking at to issue this statement only a day or so again, this event has been on the cards for at least 2 -3 days:

“Our latest guidance doesn't show any signs of any "significant" polar blasts in the first few weeks of July”

[TonyT]

Many folks in inland Canty took a hammering with the last one, and even if its a long way out, they need a good heads up for a possible next one, even if it turns out to be a fizzer.

[shovelopikis]

I have to say I don’t what models Weather Watch were looking at to issue this statement only a day or so again, this event has been on the cards for at least 2 -3 days:

“Our latest guidance doesn't show any signs of any "Significant" polar blasts in the first few weeks of July”

Weatherwatch is way to conservative with their forecasts in my opinion, last blast was well understated by them...and there min/max temps from taupo are always far too mild...the town itself had a few days in the negatives and the lowest tmin forcast would be +2 to+4...can never understand why they try play safe.

[Bradley]

Yep I can't believe I ever thought Philip Duncan was the real deal, the last 3 years through observing WW forecasts and outcomes has left me with no doubt WW is at the bottom of the food chain when it comes to accurate forecasts for the Canterbury region. I put a number of people on the forums here above him in terms of accurate forecasts - particularly medium range forecasts!

[Razor]

Watching with interest, although the latest charts on Metvuw (GFS? ) look very coastal and Banks Peninsula only for most of the three days, but a wider inland impact on Thursday for North Canterbury?

[Richard]

Watching with interest, although the latest charts on Metvuw (GFS? ) look very coastal and Banks Peninsula only for most of the three days, but a wider inland impact on Thursday for North Canterbury?

I dont think that means a lot when you consider that the wind flow is looking likely to be a direct southerly and not that typical coastal SW.
In Tony's post earlier where he said that snow of around 50cm deep could be on the cards for areas above 200m, that is a real concern

[Bradley]

Yes Richard if the below scenario plays out it could be chaos in both rural Canterbury and Christchurch itself

[mikestormchaser]

Yes Richard if the below scenario plays out it could be chaos in both rural Canterbury and Christchurch itself

Christchurch is often shelterd by a SSE wind flow and depending on sea surface temperatures the air can warm the city and then if course freeze inland. then again the sea surface temperatures are below average ATM..but places hardest hit in those wind flows are often timaru to rolleston AND inland "just south of Christchurch" and inland north canterbury.

[Razor]

Yes Richard if the below scenario plays out it could be chaos in both rural Canterbury and Christchurch itself

Christchurch is often shelterd by a SSE wind flow and depending on sea surface temperatures the air can warm the city and then if course freeze inland. then again the sea surface temperatures are below average ATM..

Indeed Mike. We saw the Banks Peninsula sheltering effect with the event a couple of weeks ago too.

[Bradley]

Latest EC run has increased the moisture levels for Christchurch but also increased the snowline with Christchurch no longer getting any snow. Plenty of time for that to change though, no doubt all the models wil flip-flop over the next 4 days...

[talbotmj15]

Maps showing cold blast with significant snow next week. thoughts

[shovelopikis]

You might want to add a few more province's to that title (in a few more runs)

[Razor]

Looks to be backing right off, even more coastal and the high coming in earlier

[NZ Thunderstorm Soc]

Tony going all out for snow next week:

NOW FORECAST: We have increasing confidence of a potentially significant snow event affecting Canterbury next ....etc.

Shouldn't that read SNOW FORECAST
MetService are really good at doing Now Forecasts, especially with maximum temperatures over the summer period.
....anyway, looks like a good snow potential next week and I hope for Tony's sake the event pulls off.