...STRONG WIND THROUGH THIS AFTERNOON...
TODAY...WINDY...RAIN...HEAVY AT TIMES IN THE MORNING...THEN RAIN SHOWERS IN THE AFTERNOON. HIGHS AROUND 46. SOUTH WIND 20 TO 30 MPH WITH GUSTS TO AROUND 40 MPH BECOMING SOUTHWEST 10 TO 20 MPH LATE IN THE AFTERNOON.

TONIGHT...RAIN SHOWERS CHANGING TO SNOW SHOWERS BY LATE EVENING. SNOW ACCUMULATION TO 1 INCH. LOWS AROUND 34. SOUTH WIND 5 TO 15 MPH.

WEDNESDAY...SNOW SHOWERS...POSSIBLY MIXED WITH RAIN IN THE
AFTERNOON. SNOW ACCUMULATION TO 1 INCH. HIGHS AROUND 39. SOUTH WIND 10 MPH.

2.1cm of rain so far in the start zones, with steady driving winds out of the south-southeast.

This storm, or more accurately combining pair of storms, is still forecast to drop another 2cm of rain up to 3000ft before changing to snow later tonight.

Yesterday saw numerous point releases and at least one wet slab in the upper layers of the snow pack as the rain and wind got going. That activity is likely to continue today, and even become more widespread, but the shallow nature of these slides makes them unlikely to reach urban areas except for the Flume/Perserverance Trails.

Glide cracks are also starting to appear in all of the Mt Juneau start zones, and these are a direct conduit to getting rainwater to the bottom of the snowpack. There exists the possibility of some glide pockets going full depth to the ground.

This hazard isn't widespread, and the pockets are small enough that they are unlikely to impact urban zones.

Once the precip changes to snow sometime around midnight tonight, the intensity should let up, and the danger will drop somewhat until we start accumulating enough storm snow through tomorrow to get new-snow hazard.

Because of the smaller expected size Avalanche Danger is MODERATE today: Natural avalanches certain, potentially destructive avalanches unlikely to come near or reach developed areas. Human triggered avalanches likely. In Urban Zones extra caution is advised due to the heavy destructive nature of even smaller wet slides. Backcountry Travel is generally not recommended.

WET SLAB AVALANCHES

Wet slab avalanches are caused by a thick cohesive slab of snow losing its bond to an underlying thin, weaker layer or interface after becoming damp, moist, or saturated with water.

The slab that initially fails can be very firm or even hard but once moving, the debris generally becomes a dense mushy mass, often composed of large rounded lumps and unaccompanied by a powder cloud. Wet slab avalanches, which are generally slower moving than dryer slab types, tend to flow in channels and are easily deflected by irregularities in the terrain. The deposited debris commonly has channels and ridges on the surface.

Wet slabs are often highly destructive due to great mass created by the high water content of the snow.

Extended periods of temperatures above the freezing point (especially if there is no overnight freeze), strong solar radiation, and rainfall are the weather events associated with wet slab formation, and are therefore, typically a late spring phenomenon. This is when temperatures are warm enough, solar radiation is strong enough, and/or rainfall amounts are great enough to produce the thick wet layers required to produce this type of avalanche. The exception may be low elevation areas, especially in maritime climates where extended warm spells and significant rainfall can occur at almost any time of year.

In the early stages of wet slab activity, the problem is often cyclical and persists only for hours as the wet surface layers freeze overnight and thaw the next day. During periods where no overnight re-freezing occurs, however, it is possible for wet slab activity to persist for days.

Snowballing, pinwheeling, and small wet slab or loose wet avalanches are often precursors of wet slab activity. Recent wet slab activity is a reliable indicator of the terrain on which another cycle will occur if the conditions that triggered the previous cycle reoccur. Current wet slab activity is generally a very good indicator for similar terrain.

GLIDE AVALANCHES

Full-depth wet slab avalanches often start with glide cracks. Like crevasses in glaciers, glide cracks are gaping fissures that form when the entire snowpack slowly slides as a unit on the ground. Glide cracks often don?t produce avalanches but occasionally and unpredictability they release catastrophically as a glide avalanche.