Tuesday – Friday 3/21-24

Issued: Tue, Mar 21, 2017 at 8AM

Expires: Fri, Mar 24, 2017

North winds are back. These winds will stiffen up the fresh powder into a slab. Look for wind loaded slopes and play with caution.

Join the VAC Basecamp FREE classes every day this week in the One Love Lot (MP 29.5). Check our Facebook page for more details! Today’s class 3-5pm: Recognizing Avalanche Terrain

 

 

Above 2,500ft Considerable

1,800 to 2,500ft Considerable

Below 1,800ft Low

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

TUESDAY WEDNESDAY THURSDAY & FRIDAY

DANGER SCALE

 

WIND SLAB:
Elevation:   Above 2000′
Aspect:  Lee to northerly and easterly winds
Terrain:   Near ridges, gullies, rollovers
Sensitivity:   Responsive
Distribution:   Specific
Likelihood (Human Triggered):   Likely
Size:   Small – Large
Danger Trend:   Steady
Forecaster Confidence:   Good

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

AVALANCHE PROBLEM TOOLBOX <here>

SNOWPACK DISCUSSION:

Maritime (Coastal) Specific: 

Certain Maritime zones have a variation of new snow from the last 48 hours. Cordova reported 8 inches at sea level yesterday AM, with 2 feet at 1000′, while the town of Valdez received 2 inches with 1 foot at the pass. If you head South, like to The Books or Marshall Pass, you might find deeper snow than in town or on the pass. More snow equals more fresh avalanches. While on the contrary more interior areas like the Tonsina Valley might have only seen a dusting.

The surfaces under the fresh powder are favorable for avalanches, and winds are picking up(45+ MPH) which will stiffen up this fresh powder into a cohesive slab. Look for fresh wind loaded slopes and limit your exposure on them. A snowmachine or a skier could easily pop off a fresh windslab that could bring you into a terrain trap.

Rain Crust from mid Feb. is now a bed surface.

Find more photos and observations at the bottom of the page. Sharing your observations creates an informed community that everyone benefits from at some point.

Recent Avalanche Activity

Maritime (Coastal) Specific: 

  • Expect human triggered windslab near ridgetops.
  • March 7 : report of two human triggered size D1 soft slabs (20cm deep on a SW aspect at 3500′ and 15cm deep on a NE aspect at 4000′). Some human triggered dry loose activity to size D1.5. With several collapses felt on low angle terrain.
  • March 2/3 : report of windslabs to size 2 released to ground near the 3000′ elevation on aspects lee to north wind.

Wind slab to ground west of Meteorite. NE aspect at ~3000′

Recent Weather

WEATHER FORECAST for NEXT 24 HRS at 3,000 ft:
Temperature Forecast (Min/Max *F):  15 / 16
Ridgetop Wind Forecast (direction/mph):  NE / 35-50
Snowfall (in/water equivalent):  2″ / 0.17″
WIND & TEMPERATURE
PAST 24 hours
Ferry Terminal Thompson Pass
Average Wind Speed (mph) / Direction  5 / ENE  30 / NE
Max Wind Gust (mph) / Direction  8 / NE  42 / NE
Temperature Min / Max (*F)  22 / 30  3 / 9

Weather Forecast: The winds from the north have returned, with gusts expected to 50MPH through the pass today. Expect temps to drop into single digits on the pass with the arrival of the north wind. There is a possibility of a few snowflakes falling today, as the low pressure system seems to be hovering to the southeast of Valdez. Areas more interior will have better visibility, but with less snow from the last 48 hours.  If the north winds allow the low pressure system to break into the mountains, we might see some snow over the next few days.

Additional Info & Media

SNOW HISTORY: Valdez 3/21 AM Thompson Pass 3/21 AM
24 Hour Snow / Water Equiv.  0.8”/.03″ 3″ /0.2″
Storm Snow /Water Equiv. (3/20)  0.8″ /.03″ 1″ /0.4″
Current Snow Depth 38″ 42″
March Snow / Water Equiv. 0.8″ /.03″ 11″ / 0.4″
Total Winter Snowfall / Water Equiv. 223.7″ /20.8” 294″ / 28.1″
Snowload in Valdez 62.4 lbs/sq. ft.

 

SNOWFALL at OTHER STATIONS:
LAST 24 HRS (3/20 AM)/STORM TOTAL (3/20)/STORM WATER EQUIV.:
Nicks Valley at 4200 ft (in): 2″ / 2″ / 0.02″
Upper Tsaina at 1750 ft (in): 0.1″ / 0.1″ / 0.01″
Sugarloaf at 550 ft (in): 0.1″/ 0.1″ / 0.01″
SNOW DEPTH & WATER SURVEY (2/28/2017) Depth Snow Water Equivalent
Milepost 2.5 Valdez  41.8″  12″
Milepost 18 42.7″ 11.5″
Milepost 29 Worthington Flats 63.6″ 18.6″
Milepost 37 Tsaina River bridge 49.3″ 12.5″
This survey is done the first week of each month.

Weather Quicklinks:

  • NWS forecast for Northeast Prince William Sound <here>
  • NOAA NWS spot forecast for Thompson Pass <here>
  • Thompson Pass RWIS weather station <here>
  • MP 30 Nicks (Happy) Valley weather station at 4200 feet <here> (scroll to Nicks Valley)
  • Valdez Glacier UAF weather station at 6600 feet <data here> <map here>
  • Further weather resources <here>

SNOW CLIMATE ZONES:

  • coastal-zone-iconMaritime (Coastal) – from the Port of Valdez to Thompson Pass, all waters flowing into Valdez Arm and everything south of Marshall Pass.
  • intermountain-zone-iconInter-mountain (Transitional) – between Thompson Pass and Rendezvous Lodge.
  • interior-zone-iconContinental (Interior) – the dry north side of the Chugach (north of 46 Mile, including the Tonsina River).

Photo of Thompson Pass

thompson-pass-ski-runs

Interactive Map of Valdez Forecast Areas w/ Many Resource Layers (Trevor Grams)

climate-zones-topoclimate-zones-satellitegoogle-earth1

Run Map of Thompson Pass Area (Sean Wisner) (2MB download)
VAC Run Map Thompson Pass

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.avalancheforecasts.com/

Posted in Maritime Forecasts.
Kyle Sobek

Forecaster: Kyle Sobek