Valdez

Forecast Expired - 01/14/2022

Above 3,000ftConsiderable

1,500 to 3,000ftConsiderable

Below 1,500ftConsiderable

Degrees of Avalanche Danger

Avalanche Problems

Problem 1

Storm Snow:

Heavy snow along with rising temperatures and strong southeast wind is forecasted for the next 24 hours.  High elevation coastal locations may receive as much as 18 inches of snow with around a foot of snow on Thompson Pass.  Snow levels are expected to rise to 1000 feet during the day causing the snow to become heavier as the storm progresses.  This will cause the upper portion of the snowpack to become top heavy, increasing the likelihood for human triggered and natural avalanches 1-2 feet in depth.  New snow avalanches will have the potential to step down to deeper layers in the snowpack creating very large hard slab avalanches.  

 

Areas where southeast wind has loaded new snow into deeper pockets in terrain steeper than 30° will be the most susceptible to human triggers.  Cautious route finding and conservative terrain choices will be necessary today.  Expect the avalanche hazard to be increasing as the day progresses.

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Problem 2

Persistent Slab:

New snow, strong winds and increasing temperatures will all be combining to stress weak/ faceted snow within our snowpack.  At this point we do not have a typical coastal Alaskan snowpack.  Instability and natural avalanche cycles will become likely with smaller changes in weather than what is typical.  It is always important to use caution while a snowpack is undergoing changes.  It is especially important with our current setup.

 

The most likely places to trigger a persistent slab avalanche will be in thin rocky areas or anywhere the snowpack is thinner and the weak layer is closer to the surface.  Other areas include places that have not been affected by recent wind events, and locations north of Thompson pass where colder temperatures has created an even weaker snowpack.  

 

 

Photo of developed facets found on Catchers Mitt on 1/6, 2mm grid.  The depth of these facets varies greatly depending upon wind redistribution.   These were found just below the surface in a wind scoured area.  On lee sides of terrain features facets may be found beneath 2-3+ feet of knife hard wind slabs.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Likelihood:

  • Almost Certain
  • Very Likely
  • Likely
  • Possible
  • Unlikely

Size:

  • Historic
  • Very Large
  • Large
  • Small

Trend

  • Increasing
  • Steady
  • Decreasing

Avalanche Activity

1/1-1/4-  The new years day wind event created an avalanche cycle that was difficult to document due to crowns being rapidly reloaded by 80 mph winds.  Below are photos of a couple very large slides that were still visible in the Hippie ridge area.  Naturals were also noted on Three Pigs, 40.5 Mile, Crudbusters, Python Buttress.

 

12/29-  Multiple natural wet loose D1-D2’s were observed in the Port of Valdez with no step downs noted.

12/23- Berlin Wall north face ~5000′ HS-N-R3-D2-O.  It is possible this occurred on 12/21, although it was not observed until 12/24.

12/21- Numerous natural avalanches observed all along the north side of Thompson Pass, as a result of strong NE wind event along with a couple inches of new snow and rising temperatures.  Observed naturals on all aspects except windward slopes with crowns originating from 1000 feet to 5500 feet in elevation.  Most of these were hard slab avalanches.  Crown depths were difficult to discern due to reloading, although some crowns looked to be up to 2 meters in depth.

12/19- D 2.5 natural avalanches were observed on the north facing buttress west of Gully 1 and Schoolbus.  

12/14-  Several natural avalanches were observed although poor visibility prevented a full view of the action.  The most notable natural was observed in Nicks Happy Valley on a NW aspect ~4000′.  Crown depth was not visible.  Debris ran down the valley and piled up at the typical snowmachine pickup.

12/8- Large remote trigger/ sympathetic avalanche event occurred 12/8 with avalanches extending from Gully 1 to Nicks.  Avalanches were soft slabs that ranged in size from D1-D3.  Over 10 separate avalanches were counted with crown depths averaging 2-3′.  One avalanche had a crown length of half a mile while another was triggered over a mile away from the point of collapse.  See observation section for full report and more photos.

12/7- Only a few natural avalanches were noted during the last storm.  It is likely there were more during the storm, but crowns may have been filled in by subsequent wind and snow.

D2’s on Town mountain was observed ~3000′

A couple of D2’s were noted in N. Oddessey gully and Big Oddessey.

D2 on 40.5 mile peak ~5500′.

12/2-12/3- Several natural D2 avalanches were noted on south aspects of Three pigs, Hippie Ridge and Averys.  These windslab avalanches originated between 4000-5500 feet elevation.

Weather

NWS Watches and Warnings

 None
 

Point forecast for Thompson Pass

Today
Snow. High near 28. Northeast wind 10 to 15 mph, with gusts as high as 40 mph. Chance of precipitation is 100%. Total daytime snow accumulation of 4 to 6 inches possible.
Tonight
Snow. Low around 22. Southeast wind 10 to 20 mph, with gusts as high as 30 mph. Chance of precipitation is 100%. New snow accumulation of 3 to 5 inches possible.
Friday
Snow likely, mainly before noon. Cloudy, with a high near 31. Southeast wind 10 to 15 mph. Chance of precipitation is 70%. New snow accumulation of around an inch possible.
Friday Night
A 40 percent chance of snow. Mostly cloudy, with a low around 20. South wind around 5 mph becoming calm.
Saturday
Snow showers. High near 23. Southeast wind 5 to 10 mph. Chance of precipitation is 80%.
Saturday Night
Snow before 9pm, then snow showers, mainly between 9pm and 3am. Low around 14. South wind 5 to 10 mph. Chance of precipitation is 80%.
Sunday
A chance of snow showers before 9am, then a chance of snow between 9am and 3pm. Mostly cloudy, with a high near 24. Chance of precipitation is 40%.
Sunday Night
Mostly cloudy, with a low around 9.

 

 Detailed forecast for Thompson Pass (mid elevation 2000-4000′)

 
DATE             THURSDAY 01/13          FRIDAY 01/14            
TIME (LT)        06    12    18    00    06    12    18    00    06
CLOUD COVER      OV    OV    OV    OV    OV    OV    OV    OV    OV
CLOUD COVER (%) 100   100   100   100    95    80    70    80    90
TEMPERATURE      23    27    26    26    29    28    25    22    23
MAX/MIN TEMP                 28          23          31          21
WIND DIR          E     E    SE    SE    SE    SE    SE    SE    SE
WIND (MPH)       20    28    25    14    14     9     4     4     8
WIND GUST (MPH)  37    51    48                                    
PRECIP PROB (%) 100   100   100   100    70    50    40    40    70
PRECIP TYPE       S     S     S     S     S     S     S     S     S
12 HOUR QPF                0.50        0.44        0.17        0.04
12 HOUR SNOW                6.3         5.5         1.2         0.0
SNOW LEVEL (KFT)0.3   0.8   1.1   1.1   1.1   0.7   0.5   0.6   0.7
 

Snow and Temperature Measurements

 

Date: 01/13 24 hr snow  HN24W* High Temp Low Temp Weekly SWE (Monday- Sunday) January Snowfall Season Snowfall HS (Snowpack depth)
Valdez 4 .35 31 26 .69 14 98 30
Thompson Pass ~3 N/O 26 24 .8 14 179 25
46 Mile Trace 0 16 N/O .2 6 37**  22

 

All snowfall measurements are expressed in inches and temperature in Fahrenheit. 24 hour sample period is from 6am-6am. 

* 24 hour snow water equivalent/ SWE.

** Season total snowfall measurements for 46 mile began December 1st.

 

Season history graphs for Thompson Pass

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Click on links below to see a clear and expanded view of above Season history graphs

 

TP WX Nov 21

 

TP wx Dec 21

 

TP wx as of 1/6

Additional Information

Winter weather began early this season, with valley locations receiving their first snowfall on the last day of Summer (September 21st).  Following this storm, above average temperatures and wet weather occurred from late September through early November.  During this time period Thompson Pass received 96 inches of  snowfall by November 7th and Valdez recorded 7.73″ of rain.  

After the 7th of November our region experienced a sharp weather pattern change.  Temperatures dropped below seasonal norms and snowfall became infrequent.  Between the time frame of November 7th- November 28th Thompson Pass only reported 19″ of snow with 1.1″ of Snow water equivalent (SWE).  Temperatures remained below 0° F for most of the period.   This cold/dry weather caused significant faceting of the snowpack, with poor structure the result.

Moderate snowfall returned to our area the last day of November and deposited 6-12 inches of new snow.  The amount varied depending upon the locations’ proximity to the coast.  As the storm exited on the 2nd of December it was quickly replaced by moderate to strong northeast winds.  

On 12/5-12/6 Valdez received 2 feet of new snow with Thompson Pass reporting 16″.  Blaring red flags like collapsing, shooting cracks and propagation in stability tests were immediately present.  On 12/8 a significant remote/ sympathetic avalanche event occurred from Gully 1 through Nick’s Happy Valley. 

Strong outflow winds began on 12/11 with periods of light snowfall.  This has caused slab thicknesses to become variable in areas exposed to NE winds.

A fair amount of natural avalanche activity occurred during the 12/11 wind event mostly on southerly aspects.  The week following this wind event fairly benign weather occurred which allowed the snowpack to adjust and for stability to improve although snowpack structure has remained poor.  

On 12/21 our area received a couple inches of snow along with temperatures rising and strong outflow winds.  This combination of weather kicked off a fairly significant natural avalanche cycle.  Many of the slabs appeared to be deeper wind slabs that were created from the 12/11 wind event.  These failed on faceted snow created in November.  The event is yet another indicator of our poor snowpack structure and its inability to receive any major change in weather without the avalanche hazard rising in conjunction.

 

On 12/26-28 warm air moved in at elevation and caused light rain to fall up to ~4000′.  A very thin rain crust was formed in many locations that was unable to support a persons weight.

 

A prolonged period of strong north winds began on new years day with wind speeds reaching 80 mph.   As winds tapered to 30-40 mph on the 5th temperatures plummeted with lows exceeding -30 F in the Tsaina valley.

 

 

Announcements

The avalanche hazard is Considerable at all elevations.  Heavy snow, strong wind, and rising temperatures bringing the snow line to 1000 feet are forecasted across our area.  Human triggered avalanches are likely 1-2 feet in depth and natural avalanches are possible.

Click the + Full Forecast button below for a list of current avalanche problems, travel advice, weather resources and more.

 

Help to improve your local avalanche center and contribute an observation to the website.  You can also contact me directly at [email protected] (907) 255-7690.