The National Weather Service Forecasts-

TODAY...RAIN SHOWERS. HIGHS AROUND 47. SOUTHEAST WIND 10 TO
20 MPH.

TONIGHT...RAIN. LOWS AROUND 42. SOUTHEAST WIND 10 TO 20 MPH.

FRIDAY...RAIN. HIGHS AROUND 48. SOUTHEAST WIND 10 TO 20 MPH.

FRIDAY NIGHT...RAIN. LOWS AROUND 42. SOUTHEAST WIND 5 TO 15 MPH.

We have seen 48mm(nearly 2\") of precip in the last 48 hours. This is a critical loading rate and adds tremendous stress to the snowpack.

Temperatures were below freezing until 1pm yesterday at the Mt Roberts Tram summit(1800'). Before this time we had 35mm of precip and 32cm of new snow (near 13\"). With continued rain after that time our snowpack settled rapidly leaving us an overall total of only 16cm of new very wet snow at that elevation.

If we look at things at a slightly higher elevation on Mt Juneau just above the White Subdivision at 2400' we see a different picture. Where it turned to rain at 1pm on Mt Roberts we kept seeing snow accumulate on Mt Juneau until nearly 6pm. This left about 43cm of new snow(almost 17\"). Warming at that elevation brought things right to the point of freezing but still delivered rains during a warm air overriding event. This started the rapid settlement of the snowpack leaving only a total of about 30cm of snow (roughly a foot). SPECIAL THANKS TO JAMIE PIERCE AND UAS FOR HELP IN IMPLEMENTING THIS WEATHER STATION> THE INFORMATION IT PROVIDES FOR AVALANCHE FORECASTING TO THE COMMUNITY IS VERY VALUABLE AND IT WOULD NOT HAVE HAPPENED WITHOUT YOU!

Our local summits are another 1000' higher in places than this weather station so you can assume we have even higher accumulation totals there and less settlement and bonding.

Yesterday morning around 11am we started to see natural avalanches occuring. Thane Road had its biggest avalanche of the year and other paths produced small avalanches. Nothing of notable size.

This shows us there was the presence of a weak layer with all this new snow, warming, and high wind loading rates.

Winds ranged from 20-over 65mph around the region during this event.

Current temps at the tram summit are 37 while Eaglecrest is 34. We expect to see additional diurnal warming today with temps increasing by as much as another 4 degrees. This will be during a period with continued precip. The forecast calls for .6\" of rain in the next 24 hours. This combination may be enough to bring down additional avalanches.

Avalanche danger is Considerable today. Natural avalanches are possible. Human Triggered Avalanches are probable.

Our greatest concern comes off or our highest mountains where we have not seen the full effect of the warming and where the snowfall amounts were the highest.

PLEASE AVOID THE FLUME TRAIL. Please avoid The Perseverance trail again today. Please do not walk in the gates sections above the Behrands neighborhood. Please also do not park and/or walk in the avalanche prone sections along Thane Road.

As we to into the weekend we expect to see very heavy rains Friday night into Saturday. Not only the new snow will be at question during this time but the lower snowpack will see the greatest stress it has seen all season. It is starting to become isothermal and will be weak during this event. Friday into Sunday will be a good time to use extreme caution in avalanche terrain. Things should start to mellow out for the remainder of the season after this time and we should go back into normal spring avalanche conditions after that. Look to see additional information on spring avalanches next week as the forecast winds down for the season.

Thanks for being careful out there Juneau and thanks for a great season!

Danger of Avalanches

Have you ever witnessed an avalanche

by Marlene Affeld

They are awesome, terrifying and among the greatest dangers to human life that one may encounter in the back country.Have you ever witnessed an avalanche? In the United States, over the past ten years there has been an average of 25 avalanche fatalities per year.

The majority of avalanches affecting people are triggered by people. Skiers, snowmobilers and everyone that travels in avalanche-prone areas should remain aware and vigilant.

An avalanche is a rapidly moving and abrupt mass flow of snow, generally mixed with water and air that thunders down the mountainside, burying anything that happens to be in its pathway. Typically avalanches are caused by an overburden of snowpack that is too massive and far too unstable for the slope that supporting it. As an avalanche crashes down the mountain it will also tear loose trees, rocks and boulders and anything else in its path that become part of the devastating barrage.

It is extremely dangerous in the mountains when a period of very cold weather is followed by a chinook wind or sudden warming trend or when rain is falling on snow pack. Free flowing water in the snow pack lubricates weak or fragile layers of the snow and often massive avalanches result. Like intense snowstorms, this is a very dangerous time to be traveling in the mountains.

Several different types of avalanches can occur. Loose snow avalanches happen when the massive weight of the snowpack exceeds the shear strength within it. This type of avalanche is most common on steep terrain and will normally release at a narrow point and then widen as it crashes down the mountain, forming a teardrop pattern.

Slab avalanches are the biggest danger and account for over ninety percent of avalanche-related fatalities. Slab avalanches form when heavy accumulations of snow are deposited on the leeward side of a mountain. These types of snow deposits form stiff, strong layers of snow. When the slab layer fails, the fracture or break in the weak layer allows massive volumes of snow to instantly fall away.. Slab avalanches are often many feet thick and hundreds of yards wide.

An isothermal avalanche, a third type of avalanche, occurs when the built-up snowpack becomes heavily saturated by water. This type also normally starts at a narrow point and spreads out as it proceeds downward.

Avalanches that form from fresh or loose snow are known as powder snow avalanches or a powder cloud. Powder clouds are a turbulent suspension of snow and air that flow as a gravity current. Powder snow avalanches are the largest of all avalanches and can flow for extremely long distances at speeds in excess of 300 miles per hour and have been known to contain over 10,000,000 tons of snow. The massive flow of snow from powder snow avalanches can flow along flat valley bottoms and even short distances uphill.

Avalanches are one of the strongest forces of nature and unpredictable by nature. Winter travel or recreation in avalanche-prone areas is never truly safe. Check the weather, donʼt get caught out when big events are imminent. Donʼt get caught out when you may lose visibility and not be aware that youʼre traveling under or near avalanche terrain.

Pay attention to avalanche warnings. Only travel in the back country with partners youʼd trust with your life. Carry safety and winter survival equipment and know how to use it.

If you are going to venture into areas where avalanches may occur, carefully consider your route. When you ski or snowmobile, never follow in the tracks of others without your own evaluation of the risk. Snow pack can change from small and benign to deadly overnight; conditions change constantly and a area that was previously stable may change quickly. A mountain slope should never be considered safe just because others have crossed it.

Observe the terrain and and take note of obvious avalanche paths where vegetation is damaged or missing, where there are few surface anchors and avoid areas of overhanging ice formations or cornices. Do not travel below others who might trigger an avalanche.

The majority of avalanches start on mountain slopes that are 30 degrees or greater. If you stay off of slopes that are 30 degrees or greater and avoid traveling beneath them, your risk is substantially minimized. Pay attention and avoid such obvious risks.

Even small avalanches are life threatening; over fifty percent of victims buried do not survive. If you remember anything about avalanche safely, remember this; most avalanches happen during or shortly after periods of intense snowfall. If snow is accumulating at a rate of an inch or more an hour avalanche danger is extreme.

Avalanches can and do happen anywhere. If you are skiing or snowmobiling, please learn about the inherent risk of avalanches and the areas you will be traversing. Accessing the most recent information for your area is crucial to enjoying your winter recreation safely and will make you a more alert and an all-around better outdoors person.