South Columbia Avalanche Forecast
Apr 9th, 2015 9:03AM
Watch for clues of changing conditions as there is potential for fresh wind slab formation on alpine features late Friday.
Fair - Forecast snowfall amounts are uncertain on Friday
FRIDAY: Freezing level holding at 2000m. Moderate SW winds at treeline, strong SW winds at ridge-top. Overcast. No significant precipitation expected during the day. On Friday night 2 to 6mm of precipitation is possible, less than 10cm of total snow expected.SATURDAY: Freezing level hovering around 1500m. 2 to 4mm precipitation possible, 2 to 10cm of snow expected. Moderate SW winds at treeline, moderate to strong SW winds at ridge-top.SUNDAY: Freezing level starting at 1000m, rising to 1500m. Moderate W/SW winds at all elevations. Overcast. No significant precipitation expected.
On Wednesday loose wet avalanches averaged size 1, with a size 2.5 being reported from steep rocky terrain. Observations from Sunday, Monday and Tuesday were limited to power sluffing from steep high elevation terrain and small loose wet activity.
The current surface consists of surface facets and surface hoar. Below this is the 10 to 45cm of snow that fell last weekend. This snow remains dry on high elevation polar aspects but has turned moist on east and west facing aspects and south facing features are moving into the spring corn cycle. Just below this snow you'll the supportive late-March crust that is thought to exist up to around 2100m. Moist snow underneath the late-March crust is ubiquitous in most of the region.Two significant persistent weak layers composed of crust and facets exist in the snowpack. Although they appear to have gone dormant for the time being, we will continue to monitor them closely. Mid-March is down 40 to 80cm below the surface and Mid-February is down 80 to 140cm. Observations indicate that there is significant faceting occurring between the two crusts. While an avalanche failing at either of these interfaces is unlikely, it may still be possible on steep unsupported alpine features.
Loose wet activity may persist Friday as there is potential for a " greenhouse" scenario where clouds move into the region trapping warm air in place. While slow moving, these avalanches can be very powerful and you do not want to be caught by one.
Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>
Increased winds Friday should add to the already large cornices that loom over many features, possibly increasing the likelihood of failure. A large cornice failure may be able to trigger a slab release on slopes below.
When traveling in the alpine, be SURE you're on the ridge, and not on a cornice.>Extra caution needed on slopes that are exposed to cornices overhead.>
Valid until: Apr 10th, 2015 2:00PM