In the last 24 hours Thompson Pass and Valdez have received 7-11 inches of heavy snow in low lying areas. Upper elevations are expected to have more. On 1/19 northeast winds were stronger than forecasted, with moderate to strong winds redistributing new snow in the mid elevations of the Port of Valdez. Top heavy storm slabs now exist 6 inches-2 feet in depth depending upon elevation and exposure to wind loading. These storm slabs are loading the 1/14 buried surface hoar layer which will make surface snow more prone to triggers than it would normally be.
The surface snow is expected to be sensitive on all aspects above 2000′, but will be the most dangerous on wind loaded slopes where deeper/ stiffer slabs exist. The hazard will be increasing as winds are forecasted to increase today with gusts up to 40 mph.
Watch for signs of instability such as shooting cracks, collapsing and recent avalanche activity. If these exist in the area that you choose to travel, then triggering an avalanche is possible in terrain steeper than 32°.
Faceted snow at the base of our snowpack has not been reactive for 14 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
1/17- 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
Northeast Prince William Sound-
Including the cities of Valdez and Thompson Pass
431 AM AKST Fri Jan 20 2023
...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO
9 PM AKST THIS EVENING FOR THOMPSON PASS...
* WHAT...Blowing snow expected. Northeast wind 15 to 25 mph with
gusts to 35 mph. Visibility reduced to one half mile at times.
Total snow accumulations of 2 to 4 inches.
* WHERE...Thompson Pass.
* WHEN...From noon to 9 PM AKST Friday.
* IMPACTS...Travel could be difficult.
* ADDITIONAL DETAILS...Gusty northeast winds will rapidly develop
through Thompson Pass midday and strengthen through the
afternoon hours. Light snow will overspread the area during the
afternoon. Snow and increased winds will lead to low
visibilities in blowing snow. Snow is expected to taper off
through this evening, while winds will persist after midnight.
NWS Point forecast for Thompson Pass
Date Friday 01/20/23 Saturday 01/21/23
Time (LT) 06 12 18 00 06 12 18 00 06
Cloud Cover OV OV OV OV OV BK SC SC OV
Cloud Cover (%) 100 95 100 85 85 60 40 35 80
Temperature 25 26 26 19 23 19 13 5 11
Max/Min Temp 29 14 25 5
Wind Dir SE NE NE NE N N NE NE E
Wind (mph) 10 8 23 16 18 17 16 8 4
Wind Gust (mph) 28 36 29 25 17
Precip Prob (%) 90 80 80 50 30 10 5 0 10
Precip Type S S S S S
12 Hour QPF 0.15 0.10 0.02 0.00
12 Hour Snow 1.6 1.5 0.0 0.0
Snow Level (kft) 1.4 1.2 0.5 0.3 0.0 0.0 0.0 0.0 0.0
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 2000′ and Moderate below. Human triggered avalanches are likely 1-2 feet in depth and natural avalanches are possible. Upside down storm slabs are sitting on weak snow making human triggered avalanches likely in terrain steeper than 32°. Strong north winds will load lee slopes, creating the potential for deeper slabs to be triggered.
Posted by Gareth Brown 01/20 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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