Early Season Avy Conditions

[senorjeem]

Snowfall warning for: Arrow Slocan Lakes
Issued at 2.42 PM PST SATURDAY 1 DECEMBER 2007
TOTAL SNOWFALL ACCUMULATIONS OF AT LEAST 15 CM ARE EXPECTED IN THE KOOTENAYS AND WEST COLUMBIA BY SUNDAY NIGHT. THIS IS A WARNING THAT SIGNIFICANT SNOWFALL IS EXPECTED OR OCCURRING IN THESE REGIONS. MONITOR WEATHER CONDITIONS..LISTEN FOR UPDATED STATEMENTS.
A MAJOR WINTER STORM WILL GIVE SNOW TO THE KOOTENAYS AND WEST COLUMBIA STARTING EARLY SUNDAY MORNING. THE SNOW WILL BE HEAVY AT TIMES WITH AMOUNTS OF AT LEAST 15 CM EXPECTED BY SUNDAY NIGHT. THE SNOW WILL EASE OFF AND CHANGE TO RAIN LATE SUNDAY NIGHT TO EARLY MONDAY MORNING.

Date Issued: Friday, November 30, 2007 at 12:00 PM
Valid Until: Monday, December 03, 2007
Forecast of avalanche danger Saturday Sunday Monday
Alpine CONSIDERABLE HIGH EXTREME
Treeline MODERATE CONSIDERABLE HIGH EXTREME
Below Treeline MODERATE CONSIDERABLE EXTREME


Travel Advisory Backcountry users should continue to use caution in their approach to steep and open terrain features on Saturday and Sunday. The balancing of the scales is tenuous in regards to a weak layer of snow that was buried on the 24th. Watch out for shooting cracks and for areas where the snow has been affected by the wind.Sunday is definitely going to be a transition day. Expect a rapid change in conditions with the arrival of a warm storm system that is forecast to bring lots of wind and precipitation. Avalanche danger may skyrocket. Rising temperatures will be the first sign of the onset of the most violent part of the storm. Be wary of freezing rain at lower elevations because this may indicate rain - and rapidly rising avalanche danger - at higher elevations.Avoiding avalanche terrain and exposure to run out zones will be important because natural avalanche activity will likely become widespread. It will be crucial to continuously monitor the change that occurs this weekend. Think critically, watch the weather and check for updates.
Avalanche Activity There have been some natural and human triggered avalanches over the past few days; most have been relatively small, soft slabs or loose snow avalanches that ran fast and far. Cohesiveness of the snow that overlies theNovember 24th interface is the driver behind whether or not avalanches have been triggered. If the current forecast rings true, we could see much larger and more destructive events with a possibility of rain on Monday causing releases much deeper in the snowpack
Snowpack Anywhere from 20-40cm of recent storm snow now sits over a widespread weak layer. We're generally not yet seeing quite enough density in the slab that sits over this layer for it to fail consistently. However, it won't be long before this changes as the consistency of the storm snow changes with wind, further precipitation and rising temperatures. There is also a week layer around an ice crust near the bottom of the snowpack. Skiers, riders and sledders may be able to trigger this layer from thin rocky areas and there will certainly be more stress on this layer with what's in store for us this weekend and early next week.
Weather We're in for a wild ride this weekend. You can expect continued cold temperatures and Northerly winds until sometime on Sunday. Then the high pressure ridge that now extends all the way to the North Pole will beoverrun by a large, wet and windy pacific frontal system. Freezing levels will climb to between 1500 and 2500 meters and Southerly winds are expected to rise to in excess of 70km/hr. There is little doubt about the arrival of this system but specifics regarding timing and freezing levels remain uncertain.


Lets be careful out there.