Chris W

With the ending of La Nina here in NZ we will have relief particularly in the North Island from what has been a very wet couple of summers due to increased north-easterly rain and exposure to the tropics, including Cyclone Gabrielle which became a major disaster for Hawke's Bay around the East Cape to Auckland. In Canterbury it has reduced our sun hours while raising average temperatures but we've generally not been affected in an extreme manner. Marine heatwaves became frequent (explaining the temperature increases to a large degree), however it could be said that the number of ex-tropical cyclones impacting the country was lower than it could have been. El Nino should it develop will result in stronger and more frequent westerly winds, greater rainfall for the south and west and also increase the likelihood of extreme high temperatures and drought in eastern areas of both islands but particularly North Canterbury, the latter due to the significant foehn winds generated across the Southern Alps and Te Urewera/Ruahine/Tararua mountain ranges by westerly flows often in combination with southern ocean cyclones. However in the meantime neutral conditions are not without their hazards; some of the strongest winds I have experienced in my time here were in 2013 under a neutral regime, with 2013-14 also featuring elevated and powerful ex-tropical cyclone arrivals to NZ - most notably Lusi and Ita - plus a devastating cyclonic/southerly event for Christchurch in March 2014. Over in Australia, coastal New South Wales will likely welcome the departure of La Nina with the soaking they have received in its tenure.

Full list of records borrowed from weatherforum.nz: 39.3 .. Ashburton Aero - NZ's 2nd-highest ever Jan temp (records from 1928) 38.0 .. Akaroa - highest all-time temp (records from 1978) 37.9 .. Cheviot - highest all-time temp (records from 1983) 37.9 .. Timaru - 2nd-highest Jan temp (records from 1906) 37.5 .. Timaru Aero - highest Jan temp (records from 1962) 37.4 .. Waipara - highest Jan temp, and 2nd-highest all-time temp (records from 1973) 37.1 .. Christchurch Aero - highest Jan temp, and 2nd-highest all-time temp (records from 1954) 36.9 .. Cooptown, Banks Peninsula (records from 2017) 36.8 .. Hanmer Forest - 2nd highest Jan temp, and 3rd highest all-time temp (records from 1906) Full thread New Zealand Weather & Climate - NZ Weather Forum WWW.WEATHERFORUM.NZ

Temperature records set today all over Canterbury for January: Ashburton 39.3C Timaru 37.9C Amberley 39.4C (unofficial, but I can attest to its accuracy any time I left the office!) Christchurch 37.1C

Current warming estimated around 80C, and some output has it heading towards 100C with 10hPa temperatures of around +15C being mentioned. The 10hPa vortex has already moved as a result, and the 70hPa vortex is slowing significantly under the warm area. That linked thread details it. See also this link and video from the National Institute of Water and Atmospheric research (NIWA): https://www.niwa.co.nz/climate/seasonal-climate-outlook/seasonal-climate-outlook-september-november-2019

I am not strongly-placed to technically describe this event, however as it is only the third in the last 20 or so years and looks unprecedented in scale I thought you folks would want to read more about it. This thread from the NZ Weather Forum describes it well: https://www.weatherforum.nz/phpBB3/viewtopic.php?f=2&t=6013

Ceduna, SA just hit its record all-time high temperature of 48.4C according to BOM SA on Twitter. That’s a coastal town. This side of the ditch, 33.4C in Christchurch today but looking at mid-thirties early next week.

That would be an awesome relief, like the doctor in Perth! Except that in this case it is a front rather than a sea breeze. Meanwhile in NZ we’ve been hitting 30 a few times this week, that’ll do nicely.

One report on Twitter says that Alice Springs has recorded its highest ever temperature today. The BOM forecast for Alice is 45 and for Melbourne it is 42, which in Melbourne’s case they do reach every 3 to 5 years.

I had a look at the BOM page and saw that figure of 129mm yesterday, that is an immense amount of rain and I really feel for the people of Hobart. This system is now heading away from Australia thankfully, onwards to NZ but any comments on what happens there are not for this thread.

I’ll bow to your experience but it looks a pretty decent event to me, particularly for NSW and Tasmania. Then we’ll see whether it does the usual and ambles across the ditch to cause trouble here!

Fehi triggered a change from a very hot summer, quite glorious in December and January overall, to a very wet autumn for most of NZ. Cyclone Gita was terrible for central NZ in particular. Indeed the hydro lakes are their fullest for this time of year for around 20 years! It has been westerly-dominated from April since the cyclones and other lows soaked us in Februqry and March, but a drier and very pleasant start to May. Possible signs of a change to colder/stormier conditions mid-May, perhaps as a result of the SSW currently underway over Antarctica as I posted about in the aussie thread.

That heat looks set to make way for cooler conditions next week (BOM Access model) as a sizeable southeasterly front, driven by a major east coast/cut-off low, makes its way across Victoria and NSW as far as Queensland. There should be some storm activity with that I would imagine! Curiously there is also apprently a sudden stratospheric warming underway over the Antarctic. I haven’t experienced one as yet down here so not really sure what it might bring for Aus/NZ. Potentially more cold interludes and more significantly cold to go with that?

'Snaw', love it! Some amazing photos and videos from you guys - wish I was back in Dundee or Edinburgh on the end of this.

Windchill must be seriously cold.

Looks like you're all about to get it from some very vigorous-looking showers. Enjoy!

That's the absolute business for a coldie.

Beautiful pink 'snow sky'.

Lurking from NZ, for Pete's sake where was this when I was visiting Sunderland at Christmas?!!! Lucky so and so's all of you

Just decided to check back in from cyclone-ravaged NZ and you have both a beasterly and a Greenland high coming going by the GFS...top work guys!

Tomasz Schafernaker in his week ahead video indicated that an easterly was coming and showed interestingly enough in the graphic that the high was to the north of the UK in a very helpful position for a cold easterly. Granted a graphic is not a chart, but I do believe that the BBC place a graphic’s content where they mean it to be. I agree that the gfs output as it stands is plausible, particularly given the mild air over Southern Europe, but my experience of significant cold is that it really develops inside 24-48 hours of commencing. So I’m also prepared to believe that the gfs May come round to the other solutions. I would come down on the cold side of the fence because I see blocks as being hard to shift, but I’m not completely convinced.

GFS still sending a lot of energy north and tonight is pushing the high east very easily. It seems a little too eager to do both of those, but the Atlantic low does look very vigorous so it may be too much for the block.

After New year there look to be a couple of days for snow chances via the last several runs off the GFS op. Around the 1st/2nd further north with a weak incursion of PM air, before a more significant chance around the 5th with a low/slider again bringing TM air against PM air. After that it does look as though Atlantic ridging and height rises over Scandinavia are trending more so than lower pressures, but as has been said the uncertainty and unpredictability of this winter's synoptics and variations has been high. From my point of view it is an extremely interesting time and one loaded with potential for snow and cold.

Excellent post stodge, to me this is extremely interesting modelling and at the same time extremely interesting weather. Beats anticyclonic or mild gloom any day!

Looking at the GFS I don't think I've ever seen the polar front jet so far south - it's almost over Spain! Polar maritime air sure is getting very involved in our weather (I'm visiting the UK until Jan 8). There is potential whatever the temperatures for some very severe winds in the next week or two.

Christchurch has just experienced it's longest dry spell in 74 years, with less than 1mm for the past 46 days. Added to well above average December temperatures which have consistently stayed at around 30C. It is very hot and very dry! Remarkably the year was very wet before that, particularly winter. Christchurch airport recorded its average annual rainfall by October. A year of real extremes!