Weather Trends & Snowpack Impact for Ski Touring

~ By JonnyPublished December 20, 2019


Overview

Canadian Rockies Weather is known for being unpredictable, extremely violent, and highly variable. Over the course of a week, it is not uncommon to see a windless 5°C with sunshine. A day later will bring 100km/h winds, massive snowfall, and -30°C temperatures. These conditions do vary throughout the season, so it is good to get an understanding of what the seasonal trends are and how they can affect the snowpack.

Weather is also highly geographically dependent across the range, with storms sometimes only passing through certain areas.

One unique factor affecting the Rockies is that weather runs perpendicular to the mountain range typically. Contrast this to the Alps in Switzerland or other ranges that are parallel to weather. This is important because it means that particular in the summer, weather can “stack up” on the west side of the range. This can result in huge dumps of snow and high winds that tend to come in short, but severe storms.

In This Guide

Overview guide to Ski Touring in the Canadian Rockies
Weather Trends and Overview (You are here)
Ski Touring Resources

Weather Resources

There are a number of valuable weather resources for planning your ski touring mission in the Canadian Rockies. Be sure to take these forecasts with a grain of salt when planning your backcountry skiing trip. It is important to understand the larger cycles in weather patterns and how they change throughout the season. Use your experience and judgment and make good, conservative decisions before travelling into the backcountry.

Mountain Forecast
Spot.wx High Precision Weather Forecasts
Avalanche.ca

Early Season Canadian Rockies Weather

October – December

Apollo Bowl Ski Touring
Sam French skiing the Apollo Bowl near Mt. Hector

The early season can be a mixed bag, highly dependent on global weather conditions such as the position of the Jet Stream and Polar Vortex. These global factors will largely determine whether the Rockies are baking in +10C temperatures, or chattering in -30C deep freeze. These factors will also largely determine the snowpack composition for the rest of the season.

In good years, the season starts strong with regular dumps of snow and moderate (below 0C) temperatures throughout October and November. This can result in a nice stable snowpack and good coverage early in the season.

During these seasons, it can sometimes be possible to access and ski larger couloirs and other high consequence features before avalanche conditions ramp up. There is often a lack of overhead hazards like cornices early in the season. Cooler temperatures, low angle sun, and short days prevent afternoon warming from becoming a factor. When temperatures stay moderate without any major swings, avalanche danger can remain low for a long time as well making for an excellent early ski touring season.

Alternately, in bad years a trend of extreme cold and/or hot temperatures will delay snow coverage until later in November or December. Early cold snaps and a lack of precipitation are ideal for ice climbers. However, they create significant access issues for skiers due to the lack of coverage at lower elevations. Bashing through dense alders and navigating fallen trees is a common November-December ritual.

Even if there is good early season coverage, years with an extended period of extreme cold (-15C and below) will often result in a highly faceted snowpack as the cold sucks the moisture out of the snow. This means that ascents can quickly become extremely arduous, with upwards progress becoming impossible due to waist-deep sugar snow.

In most cases, these deep facets will then become a serious, often season-long hazard. They will continue to exist as deep persistent weaknesses, continually buried by denser snow during the mid-season and sometimes resulting in massive failures, particularly later in the season when warmer temperatures “wake up” this layer.

Regionally, Kananaskis often has a very poor early season due to a lack of snow (with the exception of the Highwood). Banff, Kootenay and Lake Louise can be a little better (depending on the year). Icefields Parkway and Yoho are typically the best, thanks to their higher altitude.

The Highwood in Kananaskis is a special case due to the road (Highwood pass) that closes by December. In good years, the high elevation of the pass and easy access of Hwy 40 can mean incredibly good early season skiing conditions in areas like Pocaterra Cirque, Ridge, Mt. Tyrwhitt and Grizzly Col.

Mid-Season Canadian Rockies Weather

January – Early March

the Mid Season Canadian Rockies Weather can bring perfect snow, but hidden dangers often lurk in the lower snowpack.

Midseason weather can remain somewhat fickle. However most seasons it is often more predictable overall than the early season. The mid-season will usually see less variable temperatures as a rule (usually ranging from -20°C to 0°C). Also common are fairly consistent storm cycle bringing fresh snow on a regular basis. While this stability usually means the snowpack is more predictable, it is very important to be aware of deep persistent layers that often exist from the early season, and how wind events and storm cycles will have an impact on these often fragile inter-layer relationships.

One of the best parts of the mid-season in the Rockies is that coverage becomes extremely good at this point. Stable weather combined with lower sun angles means solar warming isn’t too much of an issue most of the time.

Big days, big elevation and big snow is the theme. Nailing a bluebird day after a huge storm with no wind is an incredibly memorable experience.

However, there are almost always a number of serious accidents in February-March. Many keeners may start to pursue large objectives in the face of incoming storms, or pushing it too far into the alpine when winds have created dangerous slabs.

Patience is a virtue in the Rockies and could keep you alive. Avoid bigger lines and terrain until you are certain that stability will allow safe travel.

While the weather in the midseason can be good, it can also bring large storms on a regular, often unpredictable basis. These big winter storms bring in high winds, massive snowfall, and poor visibility in the alpine. It is not uncommon to be completely socked in whiteout conditions on a high snowfield or glacier, despite a previously favorable forecast. Usually, waiting a day will bring the post-storm bluebird conditions.

Transition Season

March – Early April

Transition season can be a mixed bag of perfect conditions, and extreme avalanche danger.

The transition season can be a very mixed bag weather-wise. As daytime temperatures start to rise with longer days and more direct sunshine, objective hazards quickly start to become significant issues. Cornices are often fully formed, and afternoons bring soft or isothermic snow. On the flip side, there can be cold snaps that will quickly rot out the bottom layers. A big storm or hot temperatures will create an overload situation rapidly. Sometimes only in a period of a few hours with little warning.

The biggest hazard in this time of year is definitely the transition to periods of hot weather. Rapid daytime warming can become a significant looming risk as longer days and higher sun angles become the norm.

Further, the Rockies are renowned for a deep persistent instability that seems to creep up almost every year. A weak layer often develops near the bottom of the snowpack early in the season, and this layer may become dormant throughout the season as the snowpack deepens. It is not then uncommon for this layer to “wake up” during a period of rapid warming, or sometimes mid-season by failing wind slabs stepping down to trigger these bottom facets.

When these deep persistent layers DO fail, it is catastrophic, resulting in full-depth avalanches that can often run to historic outlays. Don’t be in the way of one of these.

As March rolls around, it is very important to check the forecast when heading out. This preparation is critical to understand what the risk of warming may be. A cold -10°C morning with overcast clouds can quickly morph into blue skies, significant solar effects, and positive temperatures.

There have been many many deaths in the Rockies and other nearby ranges during the transition period from February through April. Parties failed to predict the rapid daytime increase of warming resulting in catastrophic avalanches as high alpine faces let loose, often triggering deep persistent instabilities.

An early start is CRITICAL to safety in the Candian Rockies during this time period. Remaining observant is also important, as predictions can be wrong and sometimes temperatures will rise faster than expected.

Some good news

Despite these dangers, the transition season can offer some of the best snow and conditions throughout the whole season. Full snow coverage is typical here. Longer days mean it is possible to start pursuing bigger objectives. A long period of stable temperatures can have either a positive effect or a negative effect on deeply buried persistent weak layers. In some cases, warmer temperatures and increased humidity will “heal” the pack, and result in bomber, solid conditions throughout.

In some cases, however, low humidity and cooler temps can mean those deep persistent weaknesses will remain until the end of the season. These sleeping giants are ready to release catastrophic avalanche cycles once the spring warming pattern begins. These years require a heightened level of caution as it can be very difficult to know where they remain.

It is worth pursuing northern aspects in this time period to find sheltered snow and cooler temperatures throughout the day. Be aware of any overhead hazard that may be subject to more solar warming than where you are skiing.

Late Season Weather

April – June

Canadian Rockies late season weather brings mild temperatures and perfect snow high in the alpine

For many people, April is when skiing begins in the Rockies. Highly predictable high altitude Canadian Rockies weather cycles and warming patterns mean early starts and early finishes. Typically, there has been a major avalanche cycle by late April. This can erase the deeply buried persistent layers across the whole range some seasons.

Many years will also see late storm cycles bringing massive dumps of dense, moist snow. Thise creates a short avalanche cycle, and then days of blower, bottomless powder. Snow remaining particularly good on sheltered northern aspects.

Solar warming is a major factor, as with transition season. However, most aspects will only see wet sluffs in the afternoon. These can be avoided with careful planning and aspect management.

That said, the snowpack can be incredibly predictable along with the predictable temperatures. Early morning starts will often mean climbing styrofoam, supportive snow to the top with perfect corn snow descents. Returning to the valley before daytime warming turns the snow isothermic is key.

A good Canadian Rockies weather forecast can also open the door for big traverses in places like the Columbia and Wapta icefields. Whiteouts can be dangerous, but high altitudes and blue skies are prime traverse conditions.