Observation: NWAC Forecaster

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Basic Information

Observation Details

Observation Date:
April 5, 2023
Submitted:
April 5, 2023
Observer:
NWAC Forecaster - Irene Henninger
Zone or Region:
West North
Location:
Anderson/Watson (2000-6000ft, SW-W-N)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced

Media/Attachments

Northerly aspects had recent dry loose natural small avalanches, and low density snow but a slight shift to a more westerly aspect now had a crust on it and moistened, with teeny rollerballs running down. Note the overhead cornice as well.
A 3cm breakable crust was present on a west aspect at 4880'. This likely occurred from snow moistening the previous day and refreezing.
A pit right on the other side of the ridge from the north-facing pit. This snowpack was completely different. It was at least half the depth, and there were several crusts in the top meter of snow.
Snow was still completely dry and right side up on north-facing aspects. No crusts were found in the top meter+ of snow. Small surface hoar was present on the surface.
1mm grid with surface hoar from a northerly aspect, 5370'. It was noticeable in most areas that still had a cold dry surface (steeper north-facing terrain).
Northwest aspects, at least at this below treeline elevation, didn't evade the sun. The top 10 or so cm was moist.

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Temperature:
35°F
Wind:
Calm
New/Recent Snowfall:
3/31 snowfall began around 2500ft. About 20-25cm deep on northerly aspects and 10-15cm deep on southerlies (or less) at higher elevations

Skies ranged from scattered to broken for much of the day. Any intense bursts of sunlight were instantly hot (temps in upper 30s at 5300ish ft) but cloud cover usually came back within 5-15min.

Very small natural dry loose avalanches were visible on steep northerly aspects. They likely ran at least 24hrs ago. No actual wet loose avalanches were seen, although plenty of golf to tennis ball-sized rollerballs fanning out were present, mainly from the previous day (west as

Snowpack Observations

Snowline started around 2000ft and by about 2500ft I started noticing softer snow from the past weekend's storm. The past few days, especially yesterday, created a patchwork of crusts and low-density surfaces, depending on what aspect you were on. Even on the microscale of little bumps in the snow, there was a breakable crust on one side and powder on the other. This was the case everywhere I traveled from about 3500ft and up.

On north-facing aspects I noticed small dry loose natural avalanches that had run probably 24+ hours ago on very steep slopes. Steep aspects that got more sun yesterday (SW, W) had very small rollerballs but no actual wet loose avalanches. Very slight subtleties in the terrain made a huge difference regarding snow surfaces- crust vs powder, and dry loose vs rollerballs.

I dug two pits very close together on opposing sides of a ridge at about 5400ft. The west-facing pit had several crusts in the top meter, although the snow was dry (by the time I was done, around noon, the surface crust) was just starting to moisten). The snowpack was surprisingly shallow, at only 261cm. Meanwhile on the opposing NE slope I didn't find any crusts and my probe couldn't find the ground. Not quite a foot of low density snow sat over increasingly harder snow for the top meter of the snowpack. I didn't get any results from pit tests. Very small sluffs, or dry loose avalanches, were produced with travel on steep northerly slopes.

Upon return, one small steep opening amidst trees at 5300, SW produced a very small wet loose avalanche that was about 15cm deep due to my pushing the snow. By the time I headed out around 1400hrs more clouds seemed to be rolling in.

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