Monday Newsfeed: Brief sea level snow in Dunedin, wind chill well below zero as cold heads north, gales over NZ including Auckland (+9 Maps)
18/08/2024 11:04pm
Freezing air from Antarctica is spreading into some southern and eastern parts of the South Island on Monday before being quickly pushed eastwards out over the Pacific Ocean from an incoming high pressure zone out of Australia on Tuesday/Wednesday.
With a large low spinning south-east of NZ and the incoming high it means windy weather will continue over NZ for Monday and even Tuesday for some, helping to dredge the cold weather northwards. Gales continue to blow in Auckland, with severe gales at times and a few power outages. Gales are blowing through other regions too as westerlies turn more south-west or southerly.
The cold blast is short lived – with milder weather mid to late week for most.
As of 11am the polar portion of the air had arrived in Dunedin with snow flurries to sea level and wind chill of -3 to -8 across the low lying and hilly city. This evening wind chill in Dunedin City will be below -6 and exposed areas may go below -10 for a time as these cold winds blow. Further inland in the high country where winds are light and calm, overnight lows may drop below -6c (air temp, not wind chill) for places like Tekapo for example. Black ice may be an issue in both main islands tonight and on Tuesday morning through alpine or high elevation areas.
As of 11am Monday the coldest air was pushing through Southland and Otago and was now heading into Canterbury, likely reaching Christchurch by early afternoon and Wellington just after sunset. The cold air then ‘falls apart’ over the North Island, and is pushed away eastwards on Tuesday.
Last week WeatherWatch.co.nz exclusively forecast sea level snow for Dunedin and gale and power outage risks in Auckland for today. Damaging winds in Auckland may not ease until tonight with WeatherWatch.co.nz maintaining a moderate risk of more outages this afternoon due to the widespread nature of these winds and the squally showers making them stronger in some localised areas.
Monday:
SNOW:
Snow flurries, heavier inland on the hills and ranges and higher elevations, continue over Monday in the South Island. Just like rain showers, snow showers can line up in one area and bring greater totals – or the hills and ranges may shelter you from much, if anything at all. Snow to sea level is possible around the Catlins and up to about Dunedin City. It may fall elsewhere in Southland and Otago to sea level or near sea level (down to 50 or 100m) – but, it’s not likely to settle long or build up to much in most instances. In fact snow totals from this event are generally not too much – but in NZ it doesn’t much snow and ice to cause travel problems in particular, due to our hilly terrain. Snowy areas remain around some parts of Canterbury too, although generally not so exposed on Monday as Southland and Otago are due to the south-west lean in airflow.
Some snow moves into the North Island on Monday PM and Tuesday AM.
GALES:
There’s a reason why forecasters often refer to these as “Antarctic Blasts” – it’s full of gale force weather as well as the cold. Gales or even Severe Gales may brush exposed coastal and alpine areas of both main islands as the cold ‘pop’ of polar air moves northwards, and another air mass out of Australia shifts in and merges with it. The high pressure zone out of south-eastern Australia is big (as they so often are in August) and is going to squeeze windy weather over New Zealand as it gets nearer.
View when winds peak by using the “Trends” feature in our free app and at RuralWeather.co.nz… or use the hourly data at WeatherWatch. It’s the easiest way to visualise the general start, peak and end of windy weather (and rain, temperatures, fog, cloud, etc too).
TEMPERATURES:
For some South Island places temperatures started dropping across yesterday/Sunday during the daytime, and didn’t stop dropping until Monday morning. A total of about 18 hours of the mercury falling. The main southerly moves up the South Island during the day, reaching Christchurch early afternoon, and Wellington around sunset/early evening.
As that high pressure zone comes in from Australia and winds ease inland, those temperatures will fall even lower overnight tonight/Tuesday morning with heavy to severe frosts possible around the South Island and some lighter frosts into the North Island.
LIVESTOCK
Snow totals will be on the lower side of things for this event for most, but it’s worth noting in Southland, Otago, Canterbury and some high elevation parts of the central to eastern North Island snow might become heavy enough to be problematic – see MetService warnings here. The latest snowfall maps show some areas of build up, but mostly around the main hills and ranges. As it so often is due to our temperate climate in NZ, and then our mountains and ranges, snow and winds can vary from community to community, region to region – but wind chill will be miserable for newborn lambs and calves on Monday and some further north may have wet (raining but not snow but close to it, which can be worse for newborn animals), cold, conditions and biting wind chill, plus hail showers for some too. Overnight Monday and into Tuesday temperatures may plummet inland, especially in the South Island, with -5 to -10 degrees possible in the high country. Using the Trends feature in our app or at RuralWeather you can see windchill, hour by hour, for your hyper-local part of New Zealand.
The positive about this event is it’s short lived in nature with Monday morning through to Tuesday morning being the coldest period. Moisture levels aren’t too huge either, and milder weather returns quickly this week (especially by day).
We’ll have more details in our Monday weather video.
These maps are powered by Weathezone, Graphics by WeatherWatch
As always drill down deeper with your hyper-local, hourly, 10 day forecasts at WeatherWatch.co.nz – or download our app. We’re proud to have NZ’s most accurate weather data and more computing power (by far) than any NZ forecaster.
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