Avalanche Advisory Archive Pre-2016

Date Issued:2010-02-10
Danger:2
Trend:3
Probability:3
Size:2
Problem:0
Discussion:

The National Weather Service Forecasts- A GRADUAL CHANGE TO A COLDER WEATHER PATTERN IS EXPECTED ACROSS SOUTHEAST ALASKA DURING THE UPCOMING WEEK. THE ABOVE NORMAL TEMPERATURES THAT HAVE BEEN OVER THE PANHANDLE SINCE LATE JANUARY ARE EXPECTED TO GIVE WAY TO NEAR NORMAL CONDITIONS THIS WEEKEND AND FALL BELOW NORMAL BY THE MIDDLE OF NEXT WEEK.

A SERIES OF WEATHER FRONTS ARE EXPECTED TO IMPACT THE PANHANDLE DURING THIS TIME WITH THE POTENTIAL FOR SEVERAL PERIODS OF SNOW OR MIXED RAIN AND SNOW.

TODAY...RAIN SHOWERS AND SNOW SHOWERS IN THE MORNING...THEN RAIN SHOWERS IN THE AFTERNOON. SNOW ACCUMULATION UP TO 1 INCH. SNOW LEVEL 200 FEET INCREASING TO 600 FEET IN THE AFTERNOON. HIGHS AROUND 37. EAST WIND TO 15 TO 20 MPH IN THE MORNING BECOMING LIGHT AND VARIABLE.

TONIGHT...MOSTLY CLOUDY. A CHANCE OF RAIN SHOWERS AND SNOW
SHOWERS IN THE EVENING...THEN A CHANCE OF SNOW LATE. LOWS AROUND 27. LIGHT WINDS. CHANCE OF PRECIPITATION 40 PERCENT.

FRIDAY...MOSTLY CLOUDY. AREAS OF FOG IN THE MORNING. A SLIGHT
CHANCE OF RAIN AND SNOW IN THE MORNING...THEN RAIN WITH SNOW
LIKELY IN THE AFTERNOON. BREEZY. SNOW ACCUMULATION UP TO 1 INCH. SNOW LEVEL 400 FEET IN THE AFTERNOON. HIGHS AROUND 37. SOUTHEAST WIND 25 MPH. CHANCE OF PRECIPITATION 90 PERCENT.

With the recent rains and warm temperatures the snow down deeper in the pack has seen quite a bit of settlement and consolidation. Yet remains quite wet with quite a bit of free moisture in the snowpack do to very little freezing and over 3.5 inches of rain in the last week.

It was above freezing at tram elevations for well over a week. This continued to destabilize the snowpack by adding to the long periods of above freezing temperatures at higher elevations.

We are below freezing again now at tram elevations for the first time in quite a while and have more than a foot of new snow at upper mountain elevations.

With our previous prolonged above freezing temperatures down low and rain the old snow in place is still quite loose and contains quite a bit of liquid. This new snow is sitting on a weak layer that has not frozen and solidified at this point yet seems to be getting stronger in the last 24 hours.

Yesterdays field work on Saddle Mountain on Douglas Island showed evidence of recent avalanches and a 22\" hard slab of new snow sitting on a 1\" layer of rounded melt formed crystals.

This is like placing a slurpee on a mirror then adding the block of new snow on top of it..the weak layer can only take so much before the block of new snow wants to slide off of the base layer. But this weak layers appears to be gaining strength and bonding better in the last 18 hours.

We have seen quite a bit of windloading during this period of new snow as well. This created slabs in windblown areas that may be a concern.

Avalanche danger is moderate at this time in the urban areas.

Avalanche danger is considerable to questionably high on Douglas Island especially at upper elevations that have seen more snow and windloading. If avalanches were to occur in these areas the chance of them being larger than in the urban areas exists as well.

Observations in the area in the last week are showing that the spring avalanche cycle is upon us quite early this year. Climax avalanches have been sighted in areas with creep and remain possible until we see a long cooling period.

At this time spatial variability is quite high. If you are a backcountry skier make sure you are making good decisions on your routes, ski lines and the snow stability in your chosen region.

Tip:

Many slopes have seen quite a bit of glide activity lately. On these faces you can see large cracks opening up at the top of the faces.

This happens as the snow on the slope face glides down the mountain. During long periods of warm temps and during rains, this often happens more and faster.

These glide cracks create a lot of stress in the slab. Be cautious in these areas as avalanche conditions there are quite unpredictable. Most avalanches occuring from glide also release at the ground so they carry quite a bit of snow that is also VERY hard and dense.

Several Climax Avalanches have been sighted recently do to this condition...

With new snow on top of these slabs the stress has been increased. The slabs are still quite unstable and are now under much more stress do t.o new snow and windloading