The Avy Rose shows the forecasted danger by elevation and aspect.
It adds more detail about where you are likely to find the dangers mentioned in the forecast. The inner circle shows upper elevations (mountain top), the second circle is middle elevations, and the outer circle represents lower elevations.
Think of the Rose as a birds-eye view of a mountain, looking down from above. The rose allows our forecasters to visually show you which parts of the mountain they are most concerned about.
Dangerous avalanche conditions exist. Storm slab avalanches 2-4 feet deep will be easily triggered by a person or machine on slopes steeper than 32°. Very cautious route finding and conservative terrain choices are encouraged. Travel in or below large avalanche paths is discouraged.
Continued snowfall since 12/11 is building the depths of storm slabs. After a break in snowfall the night of 12/12, precipitation returned stronger than forecasted. 9 inches of snow was recorded at Thompson Pass with higher amounts likely in start zones. Significant snowfall is forecasted over the next 24 hours with 3 feet possible at upper elevations.
Storm slab avalanches may be able to step down to deeper layers in our snowpack to create hard slab avalanches.
Our snowpack is currently building, which is a good thing long term. In the short term dangerous avalanche conditions exist.
New snow from this week is accumulating on a thin (weak) early season snowpack. Weak layers near the base of our snowpack are being put to the test. It would be wise to avoid avalanche terrain while this test is underway.
Human triggered avalanches 2-4 feet deep are likely to very likely today. The hazard will be increasing over the next 24 hours. A large natural avalanche cycle is becoming increasingly likely in the next 36 hours.
11/14- Debris from a D3 natural avalanche at snow slide gulch ended 100 vertical feet above the Lowe river.
Large avalanches (D2-2.5)also occurred in multiple other locations including Berlin Wall, Catchers Mitt, South Three Pigs and Billy Mitchell. The activity extends beyond this list, and mostly occurred during the peak of warming and precipitation on 11/13.
Multiple natural D1-1.5 avalanches were observed on multiple aspects at low elevation. No step downs noted.
12/1- 2 D2.5 natural avalanches were noted on Three Pigs (Beaver slide, Pig Leg). Pig leg ran into the top 1/3 of the fan and Beaver Slide stopped near the end of its track. These both likely occurred during the outflow wind event 11/26-11/29.
D2 natural wind slab was observed on 40.5 mile peak on a west aspect ~3000′. Crown depth range estimated 1-2 feet and 200′ long
12/9- Several D2 natural wind slab avalanches were observed on S-W aspects at mid elevation in the intermountain region. Crowns appeared to be 1-3 feet deep. Catchers Mitt and Gully 1 were among the spots affected.
12/12- Observation of natural activity was prevented by clouds and continuing snowfall on Thompson Pass and Valdez.
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
643 AM AKST Wed Dec 14 2022
...WINTER STORM WARNING REMAINS IN EFFECT FROM 3 PM THIS
AFTERNOON TO 3 PM AKST THURSDAY...
* WHAT...Heavy snow expected. Total snow accumulations of 12 to 30
inches. Winds gusting as high as 40 mph through Thompson Pass.
* WHERE...Northeast Prince William Sound.
* WHEN...From 3 PM this afternoon to 3 PM AKST Thursday.
NWS Point forecast for Thompson Pass
Date Wednesday 12/14/22 Thursday 12/15/22
Time (LT) 06 12 18 00 06 12 18 00 06
Cloud Cover OV OV OV OV OV OV OV SC CL
Cloud Cover (%) 90 95 100 100 100 85 70 30 5
Temperature 22 24 25 25 25 26 21 16 16
Max/Min Temp 25 24 27 14
Wind Dir S S E S S SW NE NE NE
Wind (mph) 5 3 8 25 29 16 12 18 24
Wind Gust (mph) 41 47 35 39
Precip Prob (%) 60 70 100 100 100 60 30 0 0
Precip Type S S S S S S S
12 Hour QPF 0.34 1.53 0.49 0.01
12 Hour Snow 4.3 19.4 5.8 0.0
Snow Level (kft) 0.8 1.0 1.4 1.9 1.8 1.2 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.
Our snow season began with above average precipitation and temperatures. Beginning in September, snow lines generally hung around 4500′ until 10/12. At that point our area received the first snow down to sea level with 12-16 inches on the north side of Thompson Pass.
On 10/15 wet conditions continued with the freezing line rising to 5000′ or higher. As skies finally cleared on 10/22 we were left with a thin rain saturated snowpack capped by a stout rain crust up to 4500′. Above 4500′ much deeper snowpacks existed due to significant early season snowfall at upper elevations.
Dry and cold conditions along with moderate outflow winds finished out the month of October.
On 11/1 precipitation returned with 18 inches of snow and ~1″ of SWE on Thompson Pass. This new snow was initially reactive with several natural D2 avalanches reported on Thompson Pass. These slides were running on a firm bed surface consisting of old rain crusts and old wind slabs from October.
On 11/4 a strong north wind event kicked up with 65 mph+ winds on Thompson Pass. Our snowpack received significant damage as already thin snow below 4500′ was stripped down to old wind slabs, rain crusts and the ground.
Precipitation returned on 11/8 and became heavy on 11/11. Storm totals of around 50 inches were recorded at Thompson Pass DOT between 11/8-11/13. Snow lines rose to ~3000′ near the tail end of the storm with heavy rain occurring in low lying areas.
Skies cleared on 11/14 through 11/18 with a strong temperature inversion setting up. Valley temperatures north of Thompson Pass fell to 0° F with above freezing temperatures existing above 4000 feet. Valdez temps remained mild. This weather allowed for widespread surface hoar up to 1 cm to develop in low lying areas.
Precipitation returned on 11/19, with incremental snowfall on Thompson Pass and areas north. The Valdez area received rain during this period. 12 inches have been recorded at TP DOT between 11/9-11/23.
11/26-11/29- Strong outflow (N) wind event. Many areas below 3000′ were stripped to the 11/13 rain crust, destroying the 11/19 BSH layer. Widespread very hard snow surfaces were the result.
Precipitation returned to our area on 12/5, with higher accumulation amounts near the coast. As storms cleared out on 12/7, they were directly followed by another round of strong north winds. These winds once again incurred severe damage to our snow stripping surfaces back to the 11/13 rain crust on windward aspects and further building pencil hard slabs on lees.
12/11- Significant snowfall event that dropped 12-24 inches+ in a 12 hour period.
The avalanche hazard is HIGH at upper elevations and Considerable below 4000 feet. Human triggered avalanches are likely-very likely up to 4 feet deep. Continued snowfall is creating dangerous avalanche conditions. The hazard will be increasing over the next 24 hours. Very conservative terrain choices are encouraged.
Posted by Gareth Brown 12/14 9:00am.
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.
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