“Mountain Weather and Recreation” by Matt Zaffino, KGW-8
Given the high
profile mountain climbing accidents and rescues this last winter in the
Cascades, we wanted a talk about mountain climbing weather. So, 29 guests gathered at the Old Wives Tales
restaurant in east
Matt reviewed the
basics of mountain weather and asked the audience: Why do climbers get into
trouble? These factors are crucial (and
sometimes combine): (1) “Weather window” is critical (i.e., timing), (2) Any
accident can slow you down, (3) Speed (being too rushed). Any factor, or in combination, can lead to a
compounding of errors, which can be fatal.
For example, snow caves are hard to dig out, so bringing a tent is a big
time saver, and time saved is more time given for your “weather window.” Good preparation and protection is a must, as
winds often exceed 100 mph at high elevations.
Winter weather is
often good for mountain climbing.
Specific weather events can turn benign conditions into a
life-threatening drama. On February 24,
2007, Crystal Mountain Ski Area (6700 feet) on
An avalanche forms when a slab of snow develops over a frozen layer (snow previously melted then refrozen) due to wind loading, then a trigger (e.g., sound or vibration) serves as a the catalyst for the snow slab to break off, slide down, and pick up more loose snow. An avalanche slab can be as hard as rock, as the avalanche picks up and mixes ice crystals within the snow layers.
Backcountry skiers and snow-mobilers account for 50% of avalanche fatalities. In general, January is the peak for avalanche incidents. December is the peak month for the Pacific Northwest, and, surprisingly, June (due to more folks out in the backcountry and sometimes cold spring conditions where melt and refreeze is more common), based on 1975-2005 data. Good climbing weather indicators – lenticular clouds over mountaintops (suggests impending change), cloud level, low relative humidity, and vertical wind profile data. For real-time data from the NW Avalanche Center: www.nwac.noaa.gov.
After the talk concluded, Matt answered several questions. We appreciated Matt sharing his expertise and cool powerpoint slide show with us over a good dinner.
Note-taker: Kyle Dittmer, OR-AMS President