With the potential for snow, winds could increase the windslab concern.
Above 2,500ft Moderate
1,800 to 2,500ft Low
Below 1,800ft Low
Degrees of Avalanche Danger ?
Elevation: Above 2000′
Aspect: Lee of ridges, gullies, ridgetops
Terrain: Upper elevation terrain exposed to wind
Sensitivity: Stubborn, then Touchy-Responsive into Friday
Likelihood (Human Triggered): Possible, (elevating to Likely on Friday)
Size: Small – Large
Danger Trend: Increasing through Friday
Forecaster Confidence: Fair
Elevation: Above 2500′
Aspect: All ?
Terrain: 35+ degrees steepness
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Decreasing
Forecaster Confidence: Poor
AVALANCHE PROBLEM SCALE DESCRIPTORS:
Sensitivity: Non-reactive, Stubborn, Responsive, Touchy
Distribution: Isolated, Specific, Widespread
Likelihood: Unlikely, Possible, Likely, Nearly Certain
Size: Small, Large, Very Large (size scale <here>)
Danger Trend: Increasing, Steady, Decreasing
Forecaster Confidence: Good, Fair, Poor
LIST OF AVALANCHE PROBLEMS <here>
SNOWPACK DISCUSSION: Expect new windslabs into Friday, potentially in areas they haven’t been observed in previous days.
The Feb. 12 storm brought at least two feet of snow to the maritime snow climate zone south of the Port. Much less snow accumulated in the continental snow climate zone north of Serendipity at Milepost 46. A foot of snow fell within the inter-mountian zone north of Thompson Pass.
The cold, clear weather of the past month between the 1/15 and 2/13 storms created a weak layer over the old snow and a poor bond for the new storm snow to adhere to. Furthermore, the old snow is a good, smooth bed surface. Expect easy shear results at the interface of the old snow with the new snow. Strong north winds Tuesday Feb 13 created new windslabs triggering numerous relatively small avalanches, size D2, on mostly cross-loaded slopes. Moderate winds continue to transport snow in the upper elevations.
Our persistent slab concern still exists and our test pits indicate that the primary layer of concern is buried 2-6′ (60-180cm) beneath the surface. These layers are stubborn to trigger, but due to depth, will carry larger consequences. We’re still tracking the distribution but suspect it could still be widespread, especially above 2500′. Persistent layers will be easier to trigger near rocky outcrops and where snowpack is generally thinner.
Recent Avalanche Activity
No new observations.
|WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:|
|Temperature Forecast (Min/Max *F):||11 / 27|
|Ridgetop Wind Forecast (direction/mph):||S-N/2-20|
|WIND & TEMPERATURE
PAST 24 hours
|Ferry Terminal||Thompson Pass|
|Average Wind Speed (mph) / Direction||2 / NE||17 / NE-SE|
|Max Wind Gust (mph) / Direction||7 / NNW||26 / SE|
|Temperature Min / Max (*F)||29 / 34||17 / 28|
Weather Forecast: Likely 2-6″ (5-15cm) of snow throughout today, tapering tonight. Sunny Friday trending to cloudy over the weekend. Potential for strong winds tonight into Friday.
Additional Info & Media
|SNOW HISTORY:||Valdez 2/22 AM||Thompson Pass 2/22 AM|
|24 Hour Snow / Water Equiv.||0”/ 0″||0″ / 0″|
|Storm Snow /Water Equiv. (2/12)||16” / 1.5″||12″ / 1.5″|
|Current Snow Depth||33″||77″|
|February Snow / Water Equiv.||19.6″ / 1.61″||17″ / 1.8″|
|Total Winter Snowfall / Water Equiv.||97.74″ / 23.65”||307″ / 32.1″|
|Snowload in Valdez||52 lbs/sq. ft.|
|SNOWFALL at OTHER STATIONS:
LAST 24 HRS / STORM TOTAL (Feb. 12) / STORM WATER EQUIV.:
|Nicks Valley at 4200 ft (in):||” / ” / “|
|Upper Tsaina at 1750 ft (in):||” / ” / “|
|Sugarloaf at 550 ft (in):||” / ” / “|
|SNOW DEPTH & WATER SURVEY (2/5/2018)||Depth||Snow Water Equivalent|
|Milepost 2.5 Valdez||22″||7.6″|
|Milepost 29 Worthington Flats||62″||19.4″|
|Milepost 37 Tsaina River bridge||52.6″||16.4″|
|This survey is done the first week of each month.|
- Northeast Prince William Sound NWS Weather Forecast
- Middleton Island Radar for Valdez area
- GOES Alaska water vapor satellite loop
- NOAA NWS Recreational spot forecast for Thompson Pass
- Thompson Pass MP 25.7 RWIS weather station 2740′ (Mesowest)
- Valdez Marine Ferry Terminal weather station sea level
- Nicks Happy Valley above MP 30 weather station 4200′ (scroll to Nicks Valley)
- Upper Tsaina River Snotel near MP 32 1750′
- Sugarloaf Snotel 551′
- Above Valdez Glacier Cryosphere program weather station 6600′ <map here>
- Valdez Blueberry Weather Plot observations (scroll to bottom: Valdez City)
- More Mountain Weather resources for Alaska
- GFS 16 Day Model for Valdez
- Model Average Meteogram for Valdez
SNOW CLIMATE ZONES:
- Maritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
- Inter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
- Continental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).
Photo of Thompson Pass
Interactive Map of Valdez Forecast Areas w/ Many Resource Layers (Trevor Grams)
NEWS: Our region is “one of the snowiest places on earth” – Serendipity / Rendezvous snowfall record set in 1963 <here>.
Free smart phone avalanche forecasts at: http://www.