Watch Out for Spring Avalanches in Valley Floors This Season
Spring in New Zealand brings with it a unique set of challenges for outdoor enthusiasts, particularly when it comes to avalanche safety. The risk of avalanches during this season is heightened due to milder temperatures, rain, and rapidly changing weather conditions, often resulting in avalanches larger than those seen in winter.
Causes of Spring Avalanche Risk
The main causes of this increased risk include milder temperatures and rain, which destabilize the snowpack and trigger avalanches, often larger than winter avalanches. New Zealand's maritime climate also contributes, with rapid temperature changes and freezing level shifts causing snow to melt and refreeze frequently, creating complex snow layers and instability.
Strong winds redistributing snow are another significant factor, forming dangerous wind slabs – the most common avalanche problem in New Zealand. Sun warming new snow on sunny slopes can also trigger loose wet avalanches and rollerballs.
Precautions for Reducing Risk
To reduce the risk when traveling in avalanche-prone spring terrain, it's essential to check daily avalanche forecasts from trusted sources before heading out and consistently monitor conditions. Avoiding routes known to be avalanche-prone during spring, such as the Avalanche Peak – Crow River Route, which has seasonal restrictions from July to November, is also advisable.
Exercising conservative terrain choices is crucial. This means avoiding slopes with wind slabs, areas affected by rapid warming, and steep slopes where avalanches are common. Maintaining awareness of snowpack variability, recognizing signs of wet snow instability and recent wind slab formation, is also vital.
Regional Forecasts and Challenges
Regional forecasts for avalanches rely heavily on real-time weather data and snowpack observations. Forecasters face daily challenges due to New Zealand’s dynamic climate and complex terrain. Wind slabs dominate avalanche concerns across regions, and specific areas like Treble Cone and Motatapu Chutes are notable backcountry spots with both opportunity and risk, requiring careful assessment.
Current Conditions and Advice
This year, there is a higher chance of avalanches running to the valley floor due to the Persistent Weak Layer (PWL) present in much of the Southern Alps. Heavy rainfall has already soaked the snowpack, and will continue to do so. If you are heading to areas where there is no regional avalanche forecast, follow the advice of the closest region.
Spring-like westerly fronts are forecast for the next 7 days in New Zealand. A very cautious approach to any valley travel is recommended over the next couple of weeks. Several large avalanche cycles are anticipated over this period. Triggering an avalanche could awaken the PWL, low in the snowpack, resulting in an avalanche much larger than usual.
Pay particular attention to what is above you, where you are stopping or camping, and follow the advice on www.avalanche.net.nz. These fronts are expected to generate significant precipitation (rain/snow), rising freezing levels, and strong winds. Avalanches are likely to run to the valley floor, potentially exposing trampers and hunters moving through valleys or accessing gullies or stream beds.
Stay safe and enjoy the outdoors responsibly this spring in New Zealand.
Sport enthusiasts visiting New Zealand during spring must be aware of the increased risk of avalanches that can be triggered by the combination of rain, rising temperatures, and changing weather conditions. With a higher chance of avalanches running to the valley floor due to the Persistent Weather Layer (PWL) and the forecasted spring-like westerly fronts, it is advisable to follow regional avalanche forecasts and refrain from trekking in avalanche-prone areas such as the Avalanche Peak – Crow River Route during this period.
