NZ Weather Forum

Thought this deserved its own thread given it appears to be quite a rare sequence now.

I note as I type its lunchtime and through a vast swathe the Mackenzie Basin the temperatures are still in touch with minus 10 or below

2 questions at this juncture:

1. What is the lowest maximum daytime temp at an official NZ weather station?

2. How 'special' is this event, is it just a function of more weather stations being online with better technology? or does this as suggested by a couple of weather 'experts' actually fit in a one-in-30 years event descriptor?

And a few pics out of Tekapo Tourism here to see what it really looks like

http://www.tekapotourism.com/gallery/snow_2015.html

cool photos
backs up the claims of how deep it was

Metservice are also stating tonight is most likely going to be just as cold there if not colder...

I wonder what the very coldest spot has been, considering there are only a few weather stations over quite a large geographic area, and those stations have had quite big differences. Is it likely there's some shaded hollow somewhere that has reached -25C?

Anyone been driving in this area? I'm in Queenstown at the moment, but need to head to Christchurch sometime in the next few days. I'd quite like to observe the area, it sounds very picturesque (and I'd be curious, having never felt such cold temperatures). But I'm concerned about how treacherous the roads may be. Would travelling via Central Otago and Timaru make more sense? Or would simply driving very slowly and carefully make it reasonable? Would it be more or less dangerous to wait for the weather change in the weekend, which is supposed to be warmer but unsettled?

currenty only -10 in the Tara Hills/Twizel area
amazing
could certainly get below -20c tonight?
the humidity is currently at 70%
at some stage freezing fog would form...which would slow down the temperature drop

I see looking at the database that Tara Hills has recorded a maximum of just -9.1C at 2.59pm today, surely close to an all-time record for a maximum? The coldest I could find in the usual suspects list of Ophir, Lauder and Naseby is -8.4C in Lauder in the famous 1995 cold snap…

What are we thinking the low will be overnight?

Currently -12.3C in both Pukaki and Tara Hills, and the sun hasn't even set yet.

it will have set behind the southern alps now though

I lived down in Clyde and I know a few locals who reckon their stations have come close to beating the nz record (before ranfurly's was added to the mix, but if all the major rivers down in central Otago and Mackenzie would freeze over and become roads for carts inland early 1900s then I think we can all assume at some point the -25 record has been smashed, or matched at the very least

Dropped to below minus 14 in both Twizel and Omarama now. High humidity too.

It's pretty amazing considering if you look at the temperature records at Metservice, a typical year-round low in those places is -9C. Not only is this run smashing it, it's doing it several days in a row.

I have a feeling something special is going to happen tonight around that Omarama/Pukaki region...

Bradley wrote:I have a feeling something special is going to happen tonight around that Omarama/Pukaki region...

Could well be. Colder here tonight -5.7 already.

Im not sure those who live there would say special lol, freezing fuel, lpg wont work, heat pumps useless, no water all day, cant shower, septic tanks failing, burst water pipes mmmmm think i would call it bloody horrible not special.

Perhaps a dictionary might come in hand matey, special means unique

I see it's calm and hovering around -16C at Tara Hills, so perhaps it will get lower than this morn's -21.0C…

This does appear to be a significant weather event for the Mackenzie Basin and must be a test of endurance for the residents. I am thinking that the causes are very similar to cold spells that occur in the Scottish Highlands when arctic air brings a decent snowfall and then stagnates over the area for a few days around the time of the winter solstice. The cold air gets trapped in the glens and as the outgoing radiation is greater than the incoming at that time of the year, it can get very cold at night - certainly south of -20*C, and not warm up a great deal during the day. If fog persists day maximums can be as low as -15*C. I am not familiar with the geography of the Mackenzie Basin, but the name suggest an area where cold air can pool and persist for a few days under an inversion. Is this correct?

I was rather sceptical of the recently confirmed Ranfurly figure of -25*C but it appears that it is definitely possible in this region given the right conditions.

Let's hope that MetService can confirm the observations and produce a paper on this event as a permanent record for all to see.

Looks like Tara Hills site bottoming out around -19 again

Simon Culling wrote:This does appear to be a significant weather event for the Mackenzie Basin and must be a test of endurance for the residents. I am thinking that the causes are very similar to cold spells that occur in the Scottish Highlands when arctic air brings a decent snowfall and then stagnates over the area for a few days around the time of the winter solstice. The cold air gets trapped in the glens and as the outgoing radiation is greater than the incoming at that time of the year, it can get very cold at night - certainly south of -20*C, and not warm up a great deal during the day. If fog persists day maximums can be as low as -15*C. I am not familiar with the geography of the Mackenzie Basin, but the name suggest an area where cold air can pool and persist for a few days under an inversion. Is this correct?

I was rather sceptical of the recently confirmed Ranfurly figure of -25*C but it appears that it is definitely possible in this region given the right conditions.

Let's hope that MetService can confirm the observations and produce a paper on this event as a permanent record for all to see.

Met Society conference in Nov 2014 included a short paper on the record, should be published somewhere soon if not already.

LOL - Metservice going for a -3C overnight min for Omarama - currently sitting at -15C. I though the short-term forecasts were human generated?

Bradley wrote:LOL - Metservice going for a -3C overnight min for Omarama - currently sitting at -15C. I though the short-term forecasts were human generated?

Actually that's a pretty serious blunder that's been repeated all week. I doubt that the locals use the forecasts, rather they use local knowledge. Different story for motorists , especially tourists

+8C in Tekapo at 4.30am must feel very warm after the temps of late.

+9 at Tekapo at 6.15 but still -11 down the road at Pukaki !

Simon Culling wrote:This does appear to be a significant weather event for the Mackenzie Basin and must be a test of endurance for the residents. I am thinking that the causes are very similar to cold spells that occur in the Scottish Highlands when arctic air brings a decent snowfall and then stagnates over the area for a few days around the time of the winter solstice. The cold air gets trapped in the glens and as the outgoing radiation is greater than the incoming at that time of the year, it can get very cold at night - certainly south of -20*C, and not warm up a great deal during the day. If fog persists day maximums can be as low as -15*C. I am not familiar with the geography of the Mackenzie Basin, but the name suggest an area where cold air can pool and persist for a few days under an inversion. Is this correct?
.

Fog/low cloud is an ingredient with these severe cold spells, persistent freezing fog preventing/ reducing the daytime warming.

Wafting fog in the basins can make it hard to predict daytime maximums