Urban Avalanche Advisory

Current Advisory as of

February 26, 2024

Expires 7:00 AM the following morning.

Issued By Tom Mattice

Danger Level: 2 - Moderate
View Danger Definitions

Today's Discussion

We picked up 9-10" of new snow last Thursday into Friday.  Winds were quite strong during the event.  The tram had ese51mph winds and Eaglecrest had se72mph winds.  This started building our first wind slabs on N-W facing slopes in the region.  Saturday night we saw the switch to outflow winds.  Sheep Mountain saw n88mph Saturday night and n70mph yesterday into today.  Mt Roberts also had notable winds with n42 Saturday night and n32 yesterday.  The gauge is typically somewhat sheltered from this wind angle so you can assume you saw even more wind and loading that this in the urban paths.  Once in a while Eaglecrest will miss these outflow events or see much less wind and yet Saturday night winds at Eaglecrest also hit nnw35mph and yesterday nw40mph.  Still more than enough to create some wind loading.

You now have wind slabs that have been built on opposing faces in the region.  Some perhaps older and somewhat stronger and yet some still new fresh and more sensitive to triggers.  Moderate outflow winds continue today and yet there is no new snow in the forecast for the short term keeping dangers more moderate.  Natural avalanches are not likely and yet human triggered events remain possible.

Our storm Thursday came in on top of what was a very warm wet snowpack.  This should have helped the new snow bond to the old snow surface a bit.  Temps fell throughout the storm as well which should help the storm slab overall to strengthen.  Storm totals were not all that great leading to a relatively stable snowpack and yet WINDS are your primary concern for today.

Winds are forecast to diminish over the next 12-24 hours yet no significant snow is expected.  This should limit any possibility for natural activity.  Natural avalanches are possible today simply not as likely as human triggered events.

Please continue to limit your exposure to wind loaded avalanche paths.  The avalanche size should also help to limit danger levels with slide small enough in the urban environment they should not be a great concern today and yet if your  out playing in the hills, be aware danger will be lingering for a bit longer in these more isolated wind loaded locations.

Currently its 3f on Sheep Mountain with n33-40mph winds that peaked at n70.  The tram is seeing less wind currently with ne7-8mph winds that peaked at n32mph.  Temps here are 13f after a high of 22f.  No new snow and yet we picked up about 1.4" on the gauge from wind loading.  Eaglecrest also had no new snow and yet powder patch showed 2.5" of new snow simply due to wind loading.  Temps at Eaglecrest are currently 6f after a high of 17f.  Winds are currently ne-14-17mph.  Still enough to continue to move snow.  Peak winds hit N40.

Todays sunshine may cause some very minor wet loose activity on solar aspects to the South and Southwest later in the day.  Especially in wind sheltered areas.  These would not be large in size.  Simply loose wet snow falling off tree branches, or rocks on super steep faces in the region.  Cold temps and winds may also  limit this activity greatly.

Temps are forecast to remain super cold over the next 2-3 days as we start to see new snow enter the region again tomorrow.  Forecast levels lead us to believe that avalanche danger will be building and yet overall avalanche danger should stay potentially moderate to considerable.  It is not likely that the next event will push us to HIGH danger unless the storm significantly exceeds forecast totals.

 

The National Weather Service Forecasts-

Today- Mostly clear. Highs in the mid 20s. Northwest winds 10 to 15 mph shifting to the northeast 15 to 25 mph. Near downtown juneau and douglas, northeast winds 20 to 30 mph.
Tonight- Mostly cloudy. Snow likely late. Snow accumulation up to 1 inch. Lows around 18. Northeast winds 10 to 15 mph.
Tuesday- Snow likely. Snow accumulation of 4 to 5 inches. Highs in the mid 20s. East winds 15 to 25 mph.

...MORE ACCUMULATING SNOW POSSIBLE TUESDAY INTO TUESDAY NIGHT...

A strong low currently in the Bering Sea will move east through Monday. Snow from the associated front will begin to accumulate in
earnest beginning late Monday night with impactful snowfall lasting through late Tuesday night. Any given 12-hour period may see accumulations of 3 to 6 inches during this event, which is enough to adversely impact vehicular travel and may also affect marine & aviation activities. With day time highs and overnight lows well below normal, initial snow ratios will likely be quite high, meaning "light and fluffy". At present, no significant post- frontal warm up is expected, so snow ratios may remain high throughout the event, making for easier snow removal. and more chances of dry loose avalanches.

Primary Avalanche Problem

Wind Slab

Problem Type:Wind Slab
Avalanche Size:Large
Avalanche Likelihood = Possible
Avalanche Trend = Decreasing Danger

Description

We picked up 9-10" of new snow last Thursday into Friday.  Winds were quite strong during the event.  The tram had ese51mph winds and Eaglecrest had se72mph winds.  This started building our first wind slabs on N-W facing slopes in the region.  Saturday night we saw the switch to outflow winds.  Sheep Mountain saw n88mph Saturday night and n70mph yesterday into today.  Mt Roberts also had notable winds with n42 Saturday night and n32 yesterday.  The gauge is typically somewhat sheltered from this wind angle so you can assume you saw even more wind and loading that this in the urban paths.  Once in a while Eaglecrest will miss these outflow events or see much less wind and yet Saturday night winds at Eaglecrest also hit nnw35mph and yesterday nw40mph.  Still more than enough to create some wind loading.

You now have wind slabs that have been built on opposing faces in the region.  Some perhaps older and somewhat stronger and yet some still new fresh and more sensitive to triggers.  Moderate outflow winds continue today and yet there is no new snow in the forecast for the short term keeping dangers more moderate.  Natural avalanches are not likely and yet human triggered events remain possible.

Our storm Thursday came in on top of what was a very warm wet snowpack.  This should have helped the new snow bond to the old snow surface a bit.  Temps fell throughout the storm as well which should help the storm slab overall to strengthen.  Storm totals were not all that great leading to a relatively stable snowpack and yet WINDS are your primary concern for today.

Winds are forecast to diminish over the next 12-24 hours yet no significant snow is expected.  This should limit any possibility for natural activity.  Natural avalanches are possible today simply not as likely as human triggered events.

Learn more about Wind Slab.

Secondary Avalanche Problem

Loose Wet

Problem Type:Loose Wet
Avalanche Size:Small
Avalanche Likelihood = Possible
Avalanche Trend = Decreasing Danger

Description

Todays sunshine may cause some very minor wet loose activity on solar aspects to the South and Southwest later in the day.  Especially in wind sheltered areas.  These would not be large in size.  Simply loose wet snow falling off tree branches, or rocks on super steep faces in the region.  Cold temps and winds may also  limit this activity greatly.

Learn more about Loose Wet.

Today’s Avalanche Tip

As a community the more we know the safer the snow.  Are you seeing avalanche activity?  if so please report it at the Coastal Alaska Avalanche Centers website at http://CoastalAkAvalanche.org

This database is helping us to understand how widespread instabilities are and when activity is present and peaking...  Thank you for sharing.