Valdez
Above 3,000ftConsiderable
1,500 to 3,000ftConsiderable
Below 1,500ftConsiderable
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.
Degrees of Avalanche Danger
Avalanche Problems
Problem 1
Last nights low temperature remained above freezing for the most part at valley locations from Valdez to 46 mile. From tsaina to 46 temps briefly dipped below the freezing mark although the surface of the snow remains unfrozen. Wet loose activity that does occur today will be able to gauge deeper into the snowpack due to a lack of overnight freeze and will likely be confined to low and mid elevations. Cloudy conditions will likely continue through the day preventing high temps from reaching the levels they did during the last clear cycle. This will most likely prevent wet loose activity from occurring at upper elevations.
Avoid being exposed to or traveling on slopes steeper than 35° where the surface of the snow is wet or ski penetration is greater than 6 inches due to unfrozen snow. The hazard for this problem will be on the increase through the weekend as heavy rain on snow becomes likely with high temperatures on the increase region wide.
Likelihood:
- Almost Certain
- Very Likely
- Likely
- Possible
- Unlikely
Size:
- Historic
- Very Large
- Large
- Small
Trend
- Increasing
- Steady
- Decreasing
Problem 2
Light precipitation is expected today with snow lines hovering around 1500′. This will translate to new snow up high putting pressure on the 4/22 buried surface hoar layer in specific locations and rain down low increasing the likelihood for wet loose activity.
Triggering a persistent slab avalanche up to one foot in depth remains a possibility today. 4-12 inches of snow fell on 4/22 above 3500′ depending upon location. Below 3500′ temperatures were warmer preventing much in the way of accumulation.
The 4/22 storm was deposited on near surface facets in shaded protected areas at mid-upper elevation and surface hoar up to 1 cm on upper elevation north facing terrain. On other aspects new snow was deposited on a melt freeze crust. Expect for the 4/22 buried surface hoar layer to remain reactive on high elevation north facing terrain. As additional snowfall is expected today through this weekend, this problem will increase in likelihood, depth and sensitivity as the weight of new snow adds stress to a faceted weak layer in our upper snowpack. Digging snow pits to test the 4/22 interface as well as watching for signs of instability such as shooting cracks and collapsing are good ways to assess this avalanche problem. The likelihood of this avalanche problem is expected to increase as heavier precipitation arrives on Friday.
In addition to buried surface hoar concerns, north winds developed on 4/23 that redistributed the new snow into sensitive wind slabs. These slabs were found to still have energy on 4/24 especially were they have were deposited on faceted snow. Avoid wind loaded slopes in steep upper elevations, as well as cross loaded terrain at mid-upper elevations.
Likelihood:
- Almost Certain
- Very Likely
- Likely
- Possible
- Unlikely
Size:
- Historic
- Very Large
- Large
- Small
Trend
- Increasing
- Steady
- Decreasing
Problem 3
The likelihood of deep slab avalanche activity occurring is slowly increasing, as the overnight freezing line climbs in elevation. As our snowpack makes the transition from a winter pack to a spring one, deep slab avalanches become increasingly possible. The most likely trigger to this avalanche problem would include significant wet loose activity and cornice fall. Avoiding traveling on or exposing yourself to cornices and steep solar aspects where the surface is saturated is highly recommended. As the season progresses and temperatures continue to rise, so does the possibility for deep slab avalanches to occur.
Weak snow exists at the base of our snowpack. On 4/15 our area saw the first deep slab activity occur since late February. This occurred on Meteorite (see avalanche activity section) and was a cornice fall that triggered a series of step down avalanches that eventually stepped down to the ground. This is a clear indication that large triggers can have an affect on depth hoar. Increasing temperatures are expected to produce more significant activity later in the season while our snowpack is undergoing a transition from a winter snowpack to a spring one.
This problem is very difficult to assess due its depth and the fact that signs of instability will likely not be present. You can stack the odds in your favor by avoiding steep terrain that is undergoing rapid changes such as strong solar and avoiding exposure to large triggers such as cornices.
Large natural avalanche on Meteorite triggered by cornice fall on 4/15.
Likelihood:
- Almost Certain
- Very Likely
- Likely
- Possible
- Unlikely
Size:
- Historic
- Very Large
- Large
- Small
Trend
- Increasing
- Steady
- Decreasing
Avalanche Activity
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 an avalanche consider leaving a public observation.
4/17- Large natural avalanche reported on the upper Tasnuna just east of “The Wall”. Cornice fall was likely the initial trigger with other sympathetic avalanches occurring as well as full depth step downs. SS-Nc-R2.5-D3
– Skier triggered avalanche reported in the Tasnuna valley “The Hammer” SS-ASu-D2-I down 40 cms on 4/7 buried surface hoar/ NE aspect ~5500′. 5th Skier on slope was caught and partially buried in a crevasse/ skier did not sustain any major injuries.
4/15- A cornice fall produced a series of step down avalanches on Meteorite which resulted in failure at the ground. This intiatied as a cornice fall at 6500′ that triggered an avalanche most likely at the 3/9 interface which then stepped down to a persistent slab around 6100′ NE and stepped down to the ground at 5600′ NE.
SS/HS-NC-D3-O/G 6200′ NE, step down to ground ~5600′ NE
Weather
Check out our updated weather tab! A collection of local weather stations are available for viewing with graphs and tabular data included.
NWS Watches, warnings and advisories
NONE
NWS Point forecast for Thompson Pass
Date Thursday 04/27/23 Friday 04/28/23 Time (LT) 04 10 16 22 04 10 16 22 04 Cloud Cover OV OV OV OV OV OV OV OV OV Cloud Cover (%) 90 90 90 90 100 100 100 100 85 Temperature 27 31 34 32 29 32 35 32 28 Max/Min Temp 35 29 35 27 Wind Dir E E S S S S SE NE NE Wind (mph) 13 8 6 8 13 9 4 4 11 Wind Gust (mph) Precip Prob (%) 60 60 60 80 80 80 80 80 50 Precip Type S S S S S S S S S 12 Hour QPF 0.06 0.22 0.26 0.18 12 Hour Snow 0.4 1.8 2.1 1.4 Snow Level (kft) 0.5 1.1 1.6 1.5 1.2 1.2 1.5 1.4 1.1
Click on link below for Thompson Pass weather history graph:
Date:
04/27 |
24 hr snow | HN24W* | High temp | Low temp | 72 hour SWE* | April snowfall | Seasonal snowfall | Snowpack Depth |
Valdez | 0 | .09 | 42 | 32 | .09 | 11 | 248 | 29 |
Thompson Pass | 0 | N/O | N/O | N/O | N/O | 12 | 438 | N/O |
46 mile | 0 | N/O | 47 | 30 | .2 | ~5 | ~117** | 38 |
*HN24W- 24 hour Snow water equivalent in inches
*SWE– Snow water equivalent
**46 mile seasonal snowfall total begins December 1st.
Additional Information
Click on the link below for a running summary of the seasons weather history.
Announcements
The avalanche hazard is Considerable at all elevations. Wet loose avalanches will be a growing concern today as temperatures remained above freezing at valley locations overnight along with rain on snow occurring up to 2500 feet. Human triggered and natural wet loose avalanches are likely on solar aspects at all elevations and all aspects at low elevations. The likelihood is increasing for wet loose activity to step down to deeper layers in the snowpack creating the potential for more destructive avalanches to occur. In addition to wet loose hazard, storm slabs are slowly building at upper elevation that are resting upon weak snow in upper elevation shaded terrain. Cautious route finding and conservative terrain choices are advised.
Posted by Gareth Brown 04/27 8:00 am. The last avalanche forecast will be posted on April 30.
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 through April 30th.
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.