Valdez
Above 4,000ftConsiderable
2,000 to 4,000ftConsiderable
Below 2,000ftConsiderable
Degrees of Avalanche Danger
Avalanche Problems
Problem 1
Likelihood:
- Almost Certain
- Very Likely
- Likely
- Possible
- Unlikely
Size:
- Historic
- Very Large
- Large
- Small
Trend
- Increasing
- Steady
- Decreasing
Avalanche Activity
2/21: Multiple natural and human triggered avalanches were observed 2/21.
- A natural avalanche hit the road near 37 mile. Information is limited at this time. DOT mitigation work produced other avalanches that affected the road.
- A natural released at the toe of Worthington Glacier on a slope just south of the toe on a north east aspect. Crown was over 400′ wide and crown depth averaged 3-5 feet and stepped down to over 10′ deep at one point. There was a small sympathetic associated as well.
- A small deep pocket (50′ across ~4′ deep) was observed on the East side of the highway below gully 1 that was remote triggered by snowmachines high marking above.
- Two small avalanches released off a south slope above the airstrip with unknown trigger. Many snowmachine tracks were present in the area around the slides.
2/20: Two side by side avalanches were observed on the NW shoulder of the Python buttress ~3500′. Crown 2-300′ across and ~3’+ deep, low light made it difficult to tell how far they had run. These slides may have been triggered by DOT mitigation work 2/19, but this is unconfirmed.
2/20: 2 paths on Three Pigs at mp 42 slid naturally to the middle to lower portion of their aprons, D2.5. Low clouds prevented ability to see what elevation they originated from.
2/20: A Natural avalanche was reported on the north shoulder of Mt Tiekel at ~4500′. Details were limited but the entire slope avalanched and crown was reported to be 2 meters deep. R5-D2.5~.
2/19: A Natural avalanche at 32 mile buried the Richardson higway under 10 feet of snow for ~100′. This caused the highway to close for the majority of the day. Details on the slide were limited due to poor visibility on 2/19.
2/14: Dry loose D1-2 natural avalanches were observed running over the wowie zowie ice climb in Mineral creek.
2/13: Natural and human triggered D1 avalanches were observed in keystone canyon.
2/12: A D3 avalanche at mile post 38 hit the Richardson highway and closed the road. Released on a south aspect in the upper elevation start zones, ~5500′, and stepped down around 4-4500′. Further DOT mitigation efforts on Three pigs and 40.5 mile produced no results.
2/11: Small avalanche observed on NW aspect of Dimond “promise land”, ~5500′ , R1-D1.5, wind loaded pocket just off ridge line.
-Several avalanches observed on steep benches below 2500′ on S aspect hippie ridge around MP 35. Only ran height of bench ~100′, but had long connected crowns suggesting these failed on a Persistent weak layer. Crowns ~2′ deep.
2/10: Skies cleared yesterday, from 46 mile to Thompson Pass very few natural avalanches were seen from the 27 inches of snow that fell from 2/8- 2/10.
2/8: Many full path avalanches were reported running around Valdez glacier lake.
2/6: 2 remote triggered avalanches on RFS at 1800-2000′.
- SS-ARr-R1-D1-O, N aspect, 60′ wide, 50 cm crown, 1800′, failed on buried near surface facets.
- SS-ARr-R3-D1.5-O, N aspect, 100′ wide, ~60 cm crown, 2000′, failed on buried near surface facets.
Photo of 1st remote trigger listed
-Natural avalanches observed on south aspect at mile 40, ~1800′, 1-2 feet deep and ~100′ wide. SS-NL-R2-D1.5-O. These were triggered by small snow sluffs.
2/2: Numerous Small pockets of unsupported terrain released naturally in the tsaina valley below 2000′, 2′ deep.
1/27-1/30: Naturals were observed on RFS, N aspect ~6000′,
Avalanches were also observed on -40.5 mile, ~5000′ ,W aspect, 60 m crown
– 2 paths on Three Pigs, ~5000′, SE aspect, ran into the top 1/3 of aprons.
– 3 slides on Billy Mitchell ranging from 3000′-6000′, NW- N aspect. The most significant was on the upper bowl of cry babys, ~5000′, ~200 m crown, 1-2 meters deep.
1/23- Found fresh debris in a gully off point 3848′ behind the airport. D2, ran ~2000′.
~ 1/10- There have been several natural windslabs that have released in the Thompson Pass region:
-South slope of catchers mitt, near 27 mile icefall,~3500′, ~300m wide ,~3′ deep, ran 500′ HS-N-R3-D2.5. Photo shows extent of crown, which may have been bigger and is now filled in by wind transported snow.
– Gully Between Little and Big Oddessey, NW, 4000′, ~60 M wide, ~2-4′ crown, ran 1000′
-Averys, ~4000′, SW, ~70 M wide, ran ~1000′
1/11- Two natural wind slab avalanches observed at moonlight basin, 2500′-2800′, S aspect.
The first was on the small last roll before the road and had debris chunks up to 3′ deep “crown filled in by wind”, 200′ wide.
The second was in a cross loaded gully ~ 300′ above the road, with a crown up to ~10′ deep, ~100′ wide.
Weather
2/23-
The Thompson Pass Mountain Forecast covers the mountains (above 1000 ft) surrounding Keystone Canyon through Thompson Pass to Worthington Glacier. This forecast is for use in snow safety activities and emergency management. Today Tonight Temp at 1000` 16 F -2- 4 F Temp at 3000` 7 F -7- 2 F Chance of precip 0% 0% Precip amount (above 1000 FT) 0.00 in 0.00 in Snow amount (above 1000 FT) 0 in 0 in Snow level sea level sea level Wind 3000` ridges NE 17-42 mph NE 17-48 mph Remarks...None.
24h snowfall (inches) | HN24W (inches)* | Hi Temp (F) | Low Temp (F) | February snowfall | Season Snowfall | Snow height | |
Valdez | 0 | 0 | – | – | 45 | 152 | 62 |
46 mile | 0 | 0 | 27 | 2 | 30 | 91 | 31 |
Thompson Pass “DOT” |
0 | 0 | 18 | 7 | 108 | 465 | – |
HN24W= total water received last 24 hours in inches
Thompson Pass weather history 19/20 season beginning 12/21 through 1/23. Click on links below to see full size image.
Additional Information
Strong north east winds will affect our area decreasing surface stability and further stressing weak layers deep within our snowpack.
Our area has received up to 4′ of snow with strong south east- south west winds, and warm temperatures since 2/17. Two paths on Three pigs with a south east aspect at 42 mile ran to the middle of their aprons and the lower north aspect slopes of RFS buried the highway under 10 feet of snow for ~150′ at 33 mile. It is very likely that many other natural avalanches occurred on 2/19 and 2/20. Crowns have been refilling and may make seeing previous naturals difficult once skies clear.
In areas that have received natural avalanches old instabilities will have been flushed out. In areas that did not slide weak layers deep in the snowpack still exist. These weak layers will be difficult to affect due to their depth, but would produce very large avalanches if triggered.
The amount of new snow that we have received is sufficient to produce large avalanches that fail at the new snow/old snow interface. The new snow will need time to properly bond to the underlying snowpack. This bonding process will take time and large human triggered avalanches will be likely in the meantime. As you venture out into the mountains for the first time after this storm terrain progression will be a very important tool to utilize. Test small slopes with no consequence to assess snow stability before moving out onto steeper slopes.
Forecast Confidence is Low.
Resolution is Low
There have been limited observations from interior locations due to low snow at lower elevations. Use caution if you travel in these areas.
If you see something in the mountains that could contribute to this forecast, leave a public observation. The more observations we receive, the better we can tune our forecast. If you would rather not post an observation publicly, feel free to send me an email at [email protected]
Be aware that the elevation bands have changed on our website. Low is now below 2000′, Mid is 2000-4000′ and high is 4000′ and above.
Send in your best mountain recreation photos to [email protected] so we can post a photo of the week!
Photo of the Week
Thanks to Spencer Byson for sending in this photo!
Announcements
The avalanche hazard is Considerable at all elevations. Thompson pass has received 48 inches of snow, 5.6 inches of SWE and strong SE-SW winds from storms beginning on the 17th. Strong outflow winds will begin on Thompson Pass 2/23 and are forecasted to reach speeds up to 50 mph. This wind will decrease surface stability and further stress deep instabilities in our snowpack. Natural avalanches happened on 2/22 with one burying the highway. If natural avalanches are happening without significant weather. You can be sure that it is possible for a human to trigger one on a snowmachine or skis. The avalanche hazard is Considerable at all elevations. Sunshine and deep powder will make for a lot of temptation in the mountains today. Use caution, be conservative and Live to ride another day!!