On 1/20 moderate to heavy snow along with moderate to strong north winds continued on Thompson Pass and areas to the north. The depth of snow on top of the 1/14 buried surface hoar layer is increasing with sensitivity expected to increase as well.
At this point it is unclear if the 1/14 BSH layer will remain intact and be a future problem, or if it will be absorbed into the soft snow beneath. It would be prudent to be in an assessment mindset for the time being. Watch for signs of instability such as shooting cracks or recent slab avalanche activity that would indicate that a weak layer exists in our upper snowpack. Digging snowpits and using small test slopes are both great ways to get a feel for surface stability.
At this point it is clear that a foot or more of snow has fallen along with moderate to strong north winds. This on its own is enough to make specific slopes prone to human triggers 1-2 feet in depth. Freshly wind loaded slopes where storm slabs are deeper and stiffer are going to be the most dangerous today.
The snowpack at the surface is undergoing some moderate changes, and will need time to adjust. In the meantime human triggered avalanches will be likely in specific areas.
Faceted snow at the base of our snowpack has not been reactive for 15 days, on 1/6 one outlier avalanche occurred at mid elevation near Thompson Pass (see avalanche activity section). Prior to this, avalanches haven’t occurred since 12/16 at these deep layers.
Rounding (strengthening) has been observed at these facets in all three forecast zones, but this process takes a lot of time. At this point triggering an avalanche at this layer is unlikely. Once significant snowfall returns to our area, expect for the potential to affect these deep layers to increase. The most recent storm is not expected to be big enough to affect deep persistent layers.
Unlikely does not mean impossible, and triggering an avalanche deep in the snowpack would carry significant consequences. The most likely place to affect these layers would be in thin, rocky areas in the Continental zone.
Rounding facets near the base of our snowpack from Cracked Ice at 4000′ on 1/11.
Below is a summary of observed Avalanche activity from the last 7 days. Avalanches that were noted earlier in the season can be viewed by clicking the link below.
If you trigger or observe a natural avalanche consider leaving a public observation.
Valdez Avalanche Activity
1/20- Numerous large (D2) wet loose avalanches released from steep planar slopes in the Port of Valdez. These were caused by a foot or more of snow falling with temperatures rising to 40° F at sea level directly following. No step downs noted.
1/17- Numerous wet loose point release were observed on solar aspects in the Port of Valdez. Most of these originated from rocks were the suns energy permeated into dry snow and caused surface snow to become upside down. No step down slab avalanches were observed.
-Small (D1) spin drift avalanches on the lee side of Tones Temple ridge triggered a small slab at the 1/14 BSH layer.
Check out our updated weather tab! A collection of local weather stations are available for viewing with graphs and tabular data included.
NWS Watches and warnings
NWS Point forecast for Thompson Pass
Date Saturday 01/21/23 Sunday 01/22/23
Time (LT) 06 12 18 00 06 12 18 00 06
Cloud Cover OV BK OV OV OV OV OV OV OV
Cloud Cover (%) 75 65 70 70 90 95 95 95 100
Temperature 23 19 15 9 17 23 25 22 25
Max/Min Temp 24 9 25 22
Wind Dir N NE NE E E SE E E SE
Wind (mph) 16 19 16 6 6 8 12 12 10
Wind Gust (mph) 27
Precip Prob (%) 20 10 30 20 50 70 70 70 80
Precip Type S S S S S S S
12 Hour QPF 0.03 0.04 0.11 0.20
12 Hour Snow 0.0 0.0 0.7 3.3
Snow Level (kft) 0.0 0.0 0.0 0.0 0.1 0.2 0.3 0.8 1.0
Click on link below for Thompson Pass weather history graph:
*HN24W- 24 hour Snow water equivalent in inches
*SWE– Snow water equivalent
**46 mile seasonal snowfall total begins December 1st.
Click on the link below for a running summary of the seasons weather history.
Valdez Weather History
The avalanche hazard is Considerable above 4000′ and Moderate below. Human triggered avalanches are likely in specific areas 1-2 feet in depth. Storm slabs continued to build on 1/20 that are stressing weak snow. Moderate north winds have loaded lee slopes deeper, making human triggered avalanches likely in these areas.
Posted by Gareth Brown 01/21 8:00 am.
For a description of current avalanche problems, weather information, season history and more click the (+ full forecast) button. Avalanche forecasts will be issued Wednesday-Sunday.
If you have pictures of recent natural or human triggered avalanches or notice signs of instability such as shooting cracks or collapsing, leave an observation to help improve forecast accuracy.
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