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.
Very dangerous avalanche conditions exist. Storm slab avalanches 3-4 feet deep will be easily triggered by a person or machine on slopes steeper than 32°. Travel in avalanche terrain is not recommended .
Thompson Pass DOT estimated that at least 2 feet of snow fell at road level on Thompson Pass overnight. Low lying locations experienced heavy rain with the snow line at Worthington flats as of 6 am. This new snow is falling on 1-2 feet of low density snow that has been accumulating since 12/11. Storm slabs will now be upside down, and will be at the critical point where large natural avalanches are likely and human triggered avalanches are very likely.
Strong North winds are forecasted to directly follow this storm today, which will keep the avalanche hazard elevated throughout the day.
Our snowpack is currently building, which is a good thing long term. In the short term very 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 is recommended to avoid avalanche terrain while this test is underway.
Human triggered avalanches 3-4 feet deep are very likely today. There is currently sufficient load to affect faceted layers near the base of our snowpack. It is likely that a natural avalanche cycle is currently underway.
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
...WINTER STORM WARNING REMAINS IN EFFECT UNTIL NOON AKST TODAY...
* WHAT...Heavy snow occurring. Total snow accumulations of 15 to
30 inches. Winds gusting as high as 40 mph through Thompson
* WHERE...Northeast Prince William Sound.
* WHEN...Until noon AKST today.
* IMPACTS...Potential for power outages and tree damage. Travel
could be extremely hazardous. Reduced visibility in blowing
snow toward Thompson Pass.
* ADDITIONAL DETAILS...Highest snow amounts are expected for
Thompson Pass. Accumulations in Valdez of 15 to 20 inches of
snow. Winds are expected to increase following the storm which
will reduce visibility from blowing and drifting snow.
...THE VALDEZ AVALANCHE CENTER HAS ISSUED AN AVALANCHE WARNING...
* WHAT...Avalanche warning. The avalanche danger is HIGH. Very
dangerous avalanche conditions exist.
* WHERE...For the mountains in and around Valdez and Thompson
* WHEN...In effect from Wednesday 10 PM to Thursday 1 PM AKST.
* IMPACTS...A prolonged snowfall event will intensify tonight
along with rising temperatures and strong wind. This weather
will create widespread areas of unstable snow.Human triggered
avalanches are very likely and large natural avalanches are
likely on slopes steeper than 30 degrees. Debris from avalanches
above may run into valley bottoms.
* ADDITIONAL DETAILS...It is possible that 2-3 feet of snowfall
may accumulate in the high elevations ofthe mountains in and
around Valdez/Thompson Pass.
NWS Point forecast for Thompson Pass
Date Thursday 12/15/22 Friday 12/16/22
Time (LT) 06 12 18 00 06 12 18 00 06
Cloud Cover OV OV SC FW CL CL CL CL CL
Cloud Cover (%) 100 75 45 10 5 0 0 0 5
Temperature 25 26 18 12 10 7 5 0 5
Max/Min Temp 27 6 11 -5
Wind Dir S SW NE NE NE NE NE N N
Wind (mph) 26 4 17 23 25 23 23 21 21
Wind Gust (mph) 43 34 51 51 51 51 51
Precip Prob (%) 100 40 10 0 0 0 0 0 0
Precip Type S S
12 Hour QPF 0.27 0.00 0.00 0.00
12 Hour Snow 2.4 0.0 0.0 0.0
Snow Level (kft) 2.2 0.3 0.0 0.0 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.
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.
12/12-12/15- Steady snowfall continues with short breaks between pulses. Storm ended the night of 12/15 with 2+ feet accumulating overnight above 2000′. Valley locations received heavy rain.
The avalanche hazard is HIGH. Very dangerous avalanche conditions exist today. Travel in avalanche terrain is not recommended.
Posted by Gareth Brown 12/15 8:00am.
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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