NZ Weather Forum

MS's 'Rural Monthly Outlook' predicts a colder than average August with a risk of rain extremes.

Bold statements there but given the mention of extreme rainfall especially in the west and the westerly based systems expected I doubt very much the eastern canterbury or other eastern areas will be colder than normal.

Yeah they also predicted a colder then average June and July for Christchurch - wrong. It was also need to be an exceptionally cold last 3 weeks of August for it to be below average as a whole as the first week will be well above normal. Oh well I guess these well paid experts know more then us eh

Bradley wrote:Yeah they also predicted a colder then average June and July for Christchurch - wrong. It was also need to be an exceptionally cold last 3 weeks of August for it to be below average as a whole as the first week will be well above normal. Oh well I guess these well paid experts know more then us eh

Their July summary also made no mention of a positive (in winter at least, and at any time of year for me) in that many places, including my area, had more sunshine than average for July. In my book, this July was much better than the dull cold July of 2009.

Nev wrote:MS's 'Rural Monthly Outlook' predicts a colder than average August with a risk of rain extremes.

May see one of those extreme rainfall events in northern NZ later next week.

A very interesting period of unsettled weather on the way, probably unsettled for the same amount of time for both sides of both islands just at different times.
Alot of rain and Thunderstorms for the west coasts and milder out east, but a brief wee snap late Tuesday sneaks up the east coast.
As the models show at this stage a potentially cold outbreak starting from next Saturday through until Monday /Tuesday at this stage so something to keep an eye on.

Storm Struck wrote:A very interesting period of unsettled weather on the way, probably unsettled for the same amount of time for both sides of both islands just at different times.
Alot of rain and Thunderstorms for the west coasts and milder out east, but a brief wee snap late Tuesday sneaks up the east coast.
As the models show at this stage a potentially cold outbreak starting from next Saturday through until Monday /Tuesday at this stage so something to keep an eye on.

Off to Melb later this week for a few days, happy to miss any cold outbreak here. Although Melb at this time of year isnt exactly tropical.

I will be in Central Otago next weekend, will be doing some skiing so was planning on it being cold anyway

Only a few brief spits eventuated of the forecast scattered rain in St Albans, Chch. Sunny now.

Strangely, just after 1pm I noticed a small area (just 1 property) of what looked like hail banked up against a wall by Colombo St between Bealey Ave and Salisbury St. (I was in a bus, so couldn't check it out) Ground was otherwise dry in the area, so surely must've been something else.

GFS forecasting 114 hours straight of 850hpa temps of -6C or less for mid and south Canterbury starting from next Friday night...around 25-35mm of precipitation in that period as well

18.0C max here about midday, warmest day in quite a while. Felt like Spring for a few hours

Latest GFS has upped moisture levels for this weekend up to around 35mm with a decent portion of that falling with thickness levels below 524 and 850hpa temps of at least -7C - that usually means snow to sea level in Christchurch

Bradley wrote:Latest GFS has upped moisture levels for this weekend up to around 35mm with a decent portion of that falling with thickness levels below 524 and 850hpa temps of at least -7C - that usually means snow to sea level in Christchurch

The ECMWF is similar, and shows substantial snow to sea level from Saturday night.

I was waiting for EC to come on board - was beginning to worry it was never going to like this event moisture level wise!!

But its Monday, we all know how accurate models are this far out don't we?? Although saying this, we are due for a cold outbreak with snow here in Dunedin, been a few weeks now and haven't seen snow!

Tim S wrote:But its Monday, we all know how accurate models are this far out don't we?? Although saying this, we are due for a cold outbreak with snow here in Dunedin, been a few weeks now and haven't seen snow!

Models are generally very accurate this far out in giving a general impression of the overall pattern, and the models have been consistent on this for quite a few days now. Where you can get unstuck is trying to tie down micro-details this far ahead like the exact level snow will fall to, or how many hours it will last. I feel confident enough to say expect to see some snow in the east of the South Island this weekend.

Yep will definately be some snow, as to whether it will be sea-level or 300m asl no one could possibly know yet...same goes for moisture levels, could be 5mm or 40mm. I suspect if EC keeps on liking the event then by Wednesday morning we'll be alot more confident...

Seems to have all the ingredients that I used to consider a snow maker in the good old days before the information overload that was internet, model access etc etc (arggghhh!!!)...low parked out by the Chatham's funnelling the flow into the eastern seaboard. As usual much will depend on exactly what direction the wind ends up.

And I always used to think August was normally the snow month...

Razor wrote:And I always used to think August was normally the snow month...

I used to think that but it seems as of late all the big dumps have been June ie 2012, 2013 and this year. Last year is the exception as nothing happened throughout the entire winter. I like August as it is general colder than June

Tony is clearly considering it fairly likely something big is on the way:
SNOW FORECAST:For a number of days now we have seen consistent forecast data suggesting this weekend will bring a very cold, snowy spell to Canterbury. Starting on Friday night or early Saturday, and extending through Sunday, quite likely into next Monday as well, periods of snow and sleet are expected over the region. Snow could fall as low as sea level, but we need to get a little closer to the start of the event to firm up on expectations. Above about 300m there is the potential for accumulations of 50cm or more.We will update this forecast daily between now and Friday, but for now it be aware that this weekend is likely to see weather conditions which may disrupt transport, and prove hazardous to livestock, and that these conditions may last for several days.

Bradley wrote:Tony is clearly considering it fairly likely something big is on the way:

Aren't we all? You can't have 3 days of snow (to whatever level) and not get some decent accumulations! Like it says on the tin, not sure how low or how much yet, but stay tuned.

In 1992 it was estimated nearly a million sheep and lambs died, so lets see if we can do a bit better this time.

TonyT wrote:

In 1992 it was estimated nearly a million sheep and lambs died, so lets see if we can do a bit better this time.

Yes that Aug storm numbers was made up of long wool and only recently machine shorn, blade shorn saved at least 70,000 from dieing.

Christchurch got 116mm over the 4 days back in August 92’, this event over 3-4 days is forecast by all the models to be around a third of that so the chances of this being remotely like 92’ would be pretty slim I would have thought? Or does the fact the bulk of the 30-40mm forecast for Christchurch is forecast to fall as snow mean it could be just as bad?

Bradley wrote:Christchurch got 116mm over the 4 days back in August 92’, this event over 3-4 days is forecast by all the models to be around a third of that so the chances of this being remotely like 92’ would be pretty slim I would have thought? Or does the fact the bulk of the 30-40mm forecast for Christchurch is forecast to fall as snow mean it could be just as bad?

I've no idea. The pattern is similar, as you say the data somewhat different. My point was more about the value of an early warning.

Bradley wrote:Christchurch got 116mm over the 4 days back in August 92’, this event over 3-4 days is forecast by all the models to be around a third of that so the chances of this being remotely like 92’ would be pretty slim I would have thought? Or does the fact the bulk of the 30-40mm forecast for Christchurch is forecast to fall as snow mean it could be just as bad?

As much as anything the issue is wind chill, and the impact outside ChCh where snow is generally more likely I guess. Good call of Tony to alert those out there to the potential of an adverse event.