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Archived Climbing Report - May 27, 2005

These reports were summaries based on reports from climbers and skiers, weather and avalanche reports, and prior experiences. Observations are sparse and conditions vary widely throughout the Cascades as well as with elevation and aspect on any particular mountain. The intent of these reports is to give a starting point for what to expect - but your safety and that of your partners relies on your own observations and decisions!

These reports are archives and are saved for reference only - they do not apply at this time!!!

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[Current or most recent report] - Issued sporadically as resources permit

Friday May 27, 2005

Bottom Line

With recent high temperatures the overnight refreezing has probably been poor on some days. Over the weekend there may be afternoon thunderstorms and clouds for the first part of the night. It will be a good time to plan your adventures to begin and end at an early hour, and first-hand assessment of the refreeze condition will be important.

Due to limited new information some of the following information has been retained from last week, some has been modified, and some is new. Parts may look familiar but not all of it is the same.

The Details ...

Winter and Spring Review

This has been a rather unusual winter and spring. As most people know, the winter was extremely dry. However, the spring has been quite wet and unsettled (which often seems to be the case following a dry winter). During winter the trailheads were accessible for much of the season and conditions tended towards icy. The few reports received indicated unusually good mountaineering on ice but skiing which was often character building at best. Even in late winter the SW chutes on Mt Adams were reportedly sheer ice, and there were reports of RMI guides being rescued on Rainier 4-5 days into a 2 day climb after failing to anticipate the unusual conditions on the mountain.

Current Conditions

There are few reports which any updates can be based on.

During the past week there have been rather high temperatures at times. As a result of these conditions there is a strong possibility that refreezing of the snow was minimal on at least some nights. Daytime melting has probably been rapid. This means a lot of water has been infiltrating the snowpack.

Good climbing and corn skiing require a reasonably deep freeze layer with the daytime melting not penetrating it to a point where it becomes unsupportable. With the spring conditions in general and the warm temperatures this week such a supportable refreeze layer is likely to be thin and to break down early in the day.

Weather Outlook

Cool air will move in at higher levels, more so in the southern part of the Oregon Cascades than in the north. This, in combination with solar heating forming hot air below at ground level, will cause convection cells and afternoon thunderstorms. This is another good reason to be off the mountain early.

These storms are usually very localized and can produce heavy precipitation, which will fall on a snowpack that may remain generally wet to begin with.

Since these storm cells build up from solar heating they thicken late in the day and some forecasts call for cloudiness to last into the evening, with clearing later at night. This will play a role in radiational refreezing, delaying the start of the process.

Timing

With the current situation it will be especially important to start early and end early. A group of us skiing in Europe on Saturday in similar hot weather will begin at 4:30am. The Mt Shasta climbing rangers are suggesting a turn-around time of 10 am. Don't be caught out on steep slopes too late in the day. One rule of thumb spring skiers have traditionally used is to turn around when boot penetration reaches ankle depth.

The moon is waning with over 75% illumination. It rises shortly after midnight and remains up beyond sunrise. This is an ideal part of the lunar cycle for alpine starts.

Assessing Conditions

It will be important to make your own good assessments of melt/freeze conditions in the field.

Remember that spring snow is generally wet underneath due to rain and/or meltwater. Check the thickness of any layer you can travel on. If there is only a thin firm layer on the surface it is important to be off of the slopes before that layer breaks down. It is the only thing between you and a lot of wet, incohesive snow. If the surface layer is cracking and collapsing locally as you travel it is wise to avoid similar slopes which are at all steep.

Probe through the surface you are travelling on periodically. Use a ski pole or an ice axe. If the supportable layer is deep conditions are relatively safe and your main concern will be wet surface slides as the melt layer deepens (as well as rockfall as the ice holding the "rock" together begins to warm). If the supportable layer is thin you have the bigger danger of that layer softening and failing entirely, at which point all the wet snow below is available to slide.

These are solid methods of assessing spring stability. Do not be misled by talk of snowpack layers or stability test results, such factors are only important in spring in uncommon situations.

Choice of Route

There are a few factors worth considering every year at this time.

East and Northeast slopes receive the first sun and remain warm through the afternoon once they have warmed. As a result they are usually the softest slopes and ones which should be climbed very early if they are selected at all. Postholing may occur even before sunrise. Routes on such slopes include but are not limited to: Cooper Spur (Mt Hood), Early Morning Couloir and Thayer Glacier Headwall (North Sister), and the East Face of Middle Sister.

Westerly facing slopes do not receive sun until late in the day and can begin to refreeze shortly after sunset. As a result these slopes are often firn, or even hard ice. Under current conditions they may still remain soft or develop only a thin supportable surface layer, but they have a better chance of being safe than easterly slopes and have the potential to firm up sooner in the more spring-like weather.

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