Winter brings the goods, but with it comes uncertainty

Alpine and ski enthusiasts will be rejoicing as winter snowfall continues to bolster the season. However, the forecast for the next week shows unstable and changeable weather which increases the danger in avalanche prone areas across the country.

MetService says during this active period of weather, small changes in the forecast can have a big impact on the distribution of precipitation. Therefore, NZ Mountain Safety Council (MSC) advises backcountry users to pay close attention to both the weather and New Zealand Avalanche Advisory (NZAA) forecasts. 

MetService Meteorologist Lewis Ferris says the current developing weather system is expected to continue, and bring more snow into mid-next week.  

“Winds have a more southerly component tomorrow (Saturday) and we’re expecting another bout of snow to around 400-500m, possibly quite a lot for parts of the Canterbury High Country where warmer air aloft runs over the cool air below – perfect conditions for heavy snow,” Ferris says.  

“Sunday brings a general easing in the weather, but things start to turn again come late Monday. Another burst of moisture from the north tied into a low-pressure system will have the potential to bring yet another dump of snow for South Island alpine and not so alpine areas. 
 
“This is a developing system and something to keep an eye on at this point as small changes in the low-pressure system’s position will have a big impact on the distribution of precipitation,” he says.  

MSC Chief Executive Mike Daisley says the MetService forecast translates to increased avalanche danger across most regions.

Currently there are six regions on ‘High’ avalanche danger, with all other regions besides Tongariro forecasting 'Considerable’ danger. 

"There is still some uncertainty around precipitation levels and rates, which will depend on the position of the low-pressure system. Because of this, there is also uncertainty around how this will affect the snowpack, and it will likely vary across the regions.  
 
“As a general rule of thumb, rapid changes to the snowpack will lead to more instability and more avalanche danger,” he says.  
 
The NZAA forecasters will update the 13 regional forecasts on the NZAA as new information becomes available.

Header photo: 3rd July 2022 - Dean via avalanche.net.nz

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