City and Borough of Juneau
155 S. Seward Street
Juneau, Alaska 99801
tel. 907-586-5240
fax 907-586-5385
http://www.juneau.org

Urban Avalanche Advisory

Current Advisory as of Thursday, April 17, 2014

Expires 7:00am on Saturday, April 19, 2014
Issued by Chris Eckel


Avalanche Danger Level 1

Click here for danger definitions

Avalanche Trend Level 4Avalanche Size Level 1

Click here for size definitions



Today's Discussion

TODAY ... RAIN DEVELOPING IN THE AFTERNOON. HIGHS AROUND 48.
LIGHT WINDS BECOMING SOUTHEAST 5 TO 15 MPH IN THE AFTERNOON.

TONIGHT ... RAIN. LOWS AROUND 38. SOUTHEAST WIND 5 TO 15 MPH.

FRIDAY ... RAIN SHOWERS IN THE MORNING ... THEN SCATTERED RAIN
SHOWERS IN THE AFTERNOON. HIGHS AROUND 48. SOUTHEAST WIND 10 TO
20 MPH DECREASING TO 10 MPH IN THE AFTERNOON.

Another warm, dry, day yesterday. Winds remained light out of the SSE. Temps at the Tram climbed all the way to 7.5C (45.5f), and still haven't fallen below freezing at night (3C last night).

This means that the bottom third of our start zones are soft, and mushy down to about a meter - where the snow is still that deep. We lost another 3cm of snow from that elevation yesterday ... but this is also the area where wet slides will entrain the most snow and get a bit larger.

The upper start zones remain a bit cooler with more of a freeze thaw cycle going on as confirmed by fieldwork near the top of Snow Slide Creek yesterday.

Main avalanche problem continues to be point release wet slides that can entrain until they run out of snow on the way down. These are unlikely to cause problems in developed areas. The possibility for larger wet slabs exists but is not likely in our urban zones at this time.

The avalanche danger is LOW today. Remember to minimize exposure in avalanche run-outs in the heat of the day when wet slides normally occur, and during periods of heavy rain.


Starting later this afternoon there is 3/4 water in the forecast for the next 24hrs. This will start as light rain and then the precip intensity will increase, but it is also likely to change to snow in the start zones tonight.

If we get snow tonight up high that changes back to rain in the morning then the hazard might climb to MODERATE, but overall sizes for the urban paths are expected to remain small.

Today's Avalanche Tip


TRIGGER POINTS

Trigger points are the specific areas on a slope where a trigger initiates an avalanche. Common trigger points are usually areas where either the buried weak layer is especially weak, the stress on the weak layer is especially great, or the overlying slab is thinner or softer allowing the trigger to penetrate deeper or have a greater affect on a weak layer.

Common trigger points include:

* Shallow areas in a variable depth snowpack

*Below trees, rocks, etc. where the snowpack isnít supported

*Convexities or areas of tension in the snowpack

*Beneath a rock face where the snowpack is thin, or below cornices where wind slabs lurk.

Today's Photos

Urban Avalanche Advisory Image

Urban Avalanche Advisory Image


This Advisory applies to the Mt. Juneau Avalanche Zones



CBJ Image