Visibility will be in and out today, so plan your route with options for flat light. Avoid fresh windslab on slopes steeper than 30 degrees lee to northerly wind.
Above 2,500ft Considerable
1,800 to 2,500ft Moderate
Below 1,800ft Low
Degrees of Avalanche Danger ?
Elevation: Above 2000′
Aspect: Lee of ridges, gullies, ridgetops
Terrain: Upper elevation terrain exposed to wind
Likelihood (Human Triggered): Possible
Size: Small – Large
Danger Trend: Increasing
Forecaster Confidence: Fair
Terrain: 30+ degrees steepness
Likelihood (Human Triggered): Likely
Size: Small – Large
Danger Trend: Steady
Forecaster Confidence: Fair
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>
Friday March 9, the advisory area received 5-12″ (12-30cm) of snow. This snow is now being redistributed by northerly wind. Expect fresh windslab on leeward slopes.
Extreme winds Feb. 28 – Mar. 1 scoured exposed terrain and eroded into older snow layers. The snowpack depth varies widely due to these wind events scouring the snowpack down to rock and heather, while lee of ridges, and sometimes quite far down the slope, there are pockets of windslab meters deep.
The combined effect of wind events and fewer storm events this season has produced notable density and depth differences across the advisory area. Inland areas have more snow on the ground this year than in the past several seasons. Intermountain areas have a mixed bag snowpack. Maritime areas are less deep and warm than average.
The cold, clear weather between the 1/15 and 2/13 storms grew a faceted weak layer which the subsequent storm snow did not adhere to very well. We have dropped that weak layer from our primary concerns for now, due to its depth 3-7′ (90-310cm) below most surfaces, and observers not finding it reactive in tests. This is the kind of persistent weak layer that might reactivate at some point or may be a problem in certain areas where the snowpack is quite thin. File it in the back of your mind as something to check if you are digging to identify layers.
Recent Avalanche Activity
Two natural D1 windslab avalanches observed near miles 23 and 25 of the road corridor on Friday.
|WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:|
|Temperature Forecast (Min/Max *F):||19 / 24|
|Ridgetop Wind Forecast (direction/mph):||NE /10-30|
|WIND & TEMPERATURE
PAST 24 hours
|Ferry Terminal||Thompson Pass|
|Average Wind Speed (mph) / Direction||7 / Variable||18 / NE|
|Max Wind Gust (mph) / Direction||17 / ENE||37 / NE|
|Temperature Min / Max (*F)||26 / 36||15 / 21|
Weather Forecast: Partly cloudy with NE wind to 30mph Sunday morning. Scattered snow flurries accumulating up to 8 inches at Thompson Pass through Monday. With a warm front pulling from the tropics, expect warming temps Tuesday with rain at sealevel.
Additional Info & Media
|SNOW HISTORY:||Valdez 3/11 AM||Thompson Pass 3/11 AM|
|24 Hour Snow / Water Equiv.||0”/ 0″||1″ / 0.1″|
|Storm Snow /Water Equiv. (3/9-10)||6.3” / 0.41″||14″ / 0.9″|
|Current Snow Depth||37″||69″ wind scoured|
|March Snow / Water Equiv.||9.3″ / 0.55″||16″ / 1.1″|
|Total Winter Snowfall / Water Equiv.||120.84″ / 24.92”||339″ / 34″|
|Snowload in Valdez||47 lbs/sq. ft.|
|SNOW DEPTH & WATER SURVEY (3/4/2018)||Depth||Snow Water Equivalent|
|Milepost 2.5 Valdez||32.2″||9″|
|Milepost 29 Worthington Flats||62.4″||21.2″|
|Milepost 37 Tsaina River bridge||58.4″||14.2″|
|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.