Friday to Monday, May 24-27, 2013

morning	afternoon	evening
Danger Scale

DANGER TREND: The danger increases dramatically with daytime warming and decreases slowly with overnight cooling.

AVALANCHE PROBLEMS:

Wet Avalanches: Moist and wet snow avalanches are triggered with daytime warming.

List of Avalanche Problems <here>

TRAVEL ADVISORY: Timing is everything. Avoid avalanche terrain during the heat of the day. The same snow which is solid in the morning becomes a quivering bowl of jelly while melting in the afternoon.

1. Expect to be able to trigger wet snow avalanches, and
2. afternoon avalanches to run after 10:00am on east aspects and avalanches off all aspects between noon and 7:00pm, possibly later off due west aspects, and
3. glide crack avalanche releases at any time of the day.

AVALANCHES: The widespread cycle of avalanche activity in the mid-elevations is progressively moving higher up in the upper elevations. Moist and wet snow avalanches continue to run during the heat of the day, with most of the activity size 2-2.5. Dirty avalanche debris is evidence of gouging into the old snow. Upper elevation storm snow slab avalanches have continued to release since May 19.

Avalanches are sized using the destructive scale <here>

WEATHER: Mostly warm and sunny with the chance of a sprinkle on Memorial Day.

SNOWPACK DISCUSSION: There is a lot of snow for this time of year. April was 6.7 degrees F colder than average and the first three weeks of May seemed just as cold.

The upper elevations are starting to point release where exposed to solar radiation. There is still dry cold snow on upper elevation shaded aspects. There is intense solar radiation. The sun is rising at 4:30am and setting at 11:00pm.

Expect avalanche activity in the upper elevation as the temperatures get above 50 degrees F. Climax slab avalanches, step-downs to ground, and gouging show the aspects and elevations of isothermal snow. The final question of the season is where will the isothermal snowpack release slab avalanches?

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated May 23:

CONFIDENCE: Good.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet

Monday to Thursday, May 20-23, 2013

monday	tuesday	wednesday & thursday
Danger Scale

DANGER TREND: The danger is steady. The danger increases with daytime warming and decreases with overnight cooling.

AVALANCHE PROBLEMS:

Wet Avalanches: Moist and wet snow avalanches are triggered with daytime warming.

List of Avalanche Problems <here>

TRAVEL ADVISORY: Timing is everything. Avoid avalanche terrain during the heat of the day. The same snow which is solid in the morning becomes a quivering bowl of jelly while melting in the afternoon.  Expect: 1) to be able to trigger wet snow avalanches, and 2) afternoon avalanches to run after 10:00am on east aspects and avalanches off all aspects between noon and 7:00pm, possibly later off due west aspects, and 3) glide crack avalanche releases at any time of the day.

AVALANCHES: Moist and wet snow avalanches continue to run during the heat of the day. Gouging into the old snow is evident with the dirty debris. A few upper elevation storm snow slab avalanches released with the clear skies May 19 and 20.

Numerous slab avalanches above the Port show the elevation of near isothermal snow on north aspects.

Avalanches are sized using the destructive scale <here>

WEATHER: Sunny. Spring is finally arriving as the temperatures warm up.

SNOWPACK DISCUSSION: Above 2500 feet elevation more than 70 inches of snow has fallen in May. The May 14-18 storm brought 25 inches of snow to Thompson Pass with 4.1 inches of snow water equivalent.

There is intense solar radiation. The sun rises at 4:45am and sets at 10:45pm.

Expect a widespread cycle of avalanche activity starting May 22-26 when the temperatures in the upper elevation get above 50 degrees F and the spring shed begins in earnest. The questions are – how much gouging of the old snow will occur, particularly from the upper elevations and where will the isothermal snowpack release slab avalanches?

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated May 21:

CONFIDENCE: Good.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet

Friday to Monday, May 17-20, 2013

friday	saturday	sunday & monday
Danger Scale

DANGER TREND: The danger is increasing with a forecast of two feet of new snow to accumulate by Sunday. The danger also increases with daytime warming and decreases with overnight cooling.

AVALANCHE PROBLEMS:

Storm Snow: Two feet of new snow to accumulate by Sunday.

Timing is everything: The same snow which is a little more solid in the morning becomes much less solid while melting in the afternoon. Expect afternoon avalanche activity.

Wet Avalanches: Moist and wet snow avalanches are triggered with daytime warming.

List of Avalanche Problems <here>

TRAVEL ADVISORY: Expect to be able to trigger new snow avalanches. Avoid avalanche terrain during the heat of the day.

AVALANCHES: Moist and wet snow avalanches continue to run during the heat of the day. Gouging into the old snow is evident with the dirty debris. A large, size 3, slab avalanche pulled out May 15 in the mid-elevation north aspect of Mt Sugarloaf above the Port. Also, a slab pulled out on May 15 above the airport.

There was a widespread cycle of new snow avalanches to size 2.5 on May 14. A lot of old snow moved in the mid elevations on Friday May 10 when the temperatures at Thompson Pass reached 47 degrees F in the afternoon. There was an impressive avalanche cycle  of mostly new snow on May 5 with numerous large avalanches running to the valley bottoms.

Avalanches are sized using the destructive scale <here>

WEATHER: Remaining colder than the seasonal average until spring finally arrives on May 22. Expect another two feet of snow before the skies clear Sunday. The freezing level will periodically drop to 1500 feet elevation.

SNOWPACK DISCUSSION: The cloudy weather May 8-14 prevented overnight freezing and the snowpack is isothermal in the lower and mid elevations as well as the upper elevations on aspects from SE-SW.

Well over a foot of new snow fell above 2000 feet elevation between May 10-14, mostly on the 14th. Two inches of water accumulated between the 10th and 15th.

The two feet of new snow in the forecast will point release as it accumulates during the storm. Expect avalanches when the sun shines on Sunday. The questions are – how much gouging of the old snow will occur, particularly from the upper elevations and where will the isothermal snowpack release slab avalanches?

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated May 17:

CONFIDENCE: Fair.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet

Tuesday to Friday, May 14-17, 2013

tuesday	wednesday	thursday & friday
Danger Scale

DANGER TREND: The danger is steady. The danger increases with daytime warming and decreases with overnight cooling.

AVALANCHE PROBLEMS:

Timing is everything: The same snow which is a little more solid in the morning becomes much less solid while melting in the afternoon. Expect afternoon avalanche activity.

Wet Avalanches: Moist and wet snow avalanches are triggered with daytime warming.

List of Avalanche Problems <here>

TRAVEL ADVISORY: The snowpack is generally more stable in the early morning. Avoid avalanche terrain during the heat of the day.

AVALANCHES: Moist and wet snow avalanches continue to run during the heat of the day. Gouging into the old snow is evident with the dirty debris. There was a widespread cycle of new snow avalanches to size 2.5 on May 14. A lot of old snow moved in the mid elevations on Friday May 10 when the temperatures at Thompson Pass reached 47 degrees F in the afternoon. There was an impressive avalanche cycle to size 3, possibly larger, of mostly new snow on May 5 with numerous large avalanches running to the valley bottoms.

Avalanches are sized using the destructive scale <here>

WEATHER: Remaining colder than the seasonal average. Expect close to another two inches of water between Thursday and Sunday with the freezing level periodically dropping to near sea level.

SNOWPACK DISCUSSION: The cloudy weather May 8-14 prevented overnight freezing. Well over a foot of new snow fell above the freezing level between May 10-14, mostly on the 14th. Two inches of water accumulated between the 10th and 15th.

The snowpack is isothermal in the lower and mid elevations as well as the upper elevations on aspects from SE-SW.

The new snow will point release avalanche Wednesday. It will be interesting to see how much gouging of the old snow will occur, particularly from the upper elevations.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated May 15:

CONFIDENCE: Fair.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet

Thursday to Sunday, May 9-12, 2013

thursday	friday	saturday & sunday
Danger Scale

DANGER TREND: The danger increases with daytime warming and decreases with overnight cooling.

AVALANCHE PROBLEMS:

Timing is everything: The same snow which is as solid as set concrete when frozen in the morning is not unlike wet concrete when melting in the afternoon. More than five feet of new snow accumulated above 3500 feet elevation during the record setting storm May 2-5. Expect afternoon avalanche activity.

Wet Avalanches: Moist and wet snow avalanches are triggered with daytime warming.

List of Avalanche Problems <here>

TRAVEL ADVISORY: Although the snowpack is generally more stable in the early morning, particularly where a thick crust forms overnight, avoid avalanche terrain during the heat of the day, especially avalanche terrain exposed to direct solar radiation.

AVALANCHES: Moist and wet snow avalanches are starting to run during the heat of the day. There was an impressive avalanche cycle May 4-5. Numerous large avalanches with crown lines to 10 feet deep ran to the valley bottoms and into the Port of Valdez. Avalanches running down Snowslide Gulch at Milepost 16 may have briefly blocked the Lowe River.

Avalanches are sized using the destructive scale <here>

WEATHER: Sunny until the weekend. Cloudy with the chance of a raindrop over the weekend. Warm. A few more sprinkles after the weekend.

SNOWPACK DISCUSSION: Overnight freezing has made a thick crust over the moist snow in the mid elevation. The crust softens and melts with daytime warming, finally developing some corn snow.

There still is a lot of storm snow available to avalanche off the mountain tops. Where the snowpack didn’t avalanche during the storm, solar radiation is triggering new snow avalanches. There is some gouging into the old snow. Expect more gouging and avalanche releases to ground as the spring shed gets underway.

The 5 inches of water added to the snowpack in the May 2-5 storm that deposited 41 inches of snow at Thompson Pass has 32 inches of snow water equivalent (SWE), making the snowpack, where wind affected, an impressive 42% water. During the storm on May 4th, 2 inches of new snow had 1.1 inches of SWE.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated May 8:

CONFIDENCE: Fair.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet

Tuesday to Friday, May 7-10, 2013

tuesday	wednesday	thursday & friday
Danger Scale

DANGER TREND: The danger increases with daytime warming and decreases with overnight cooling.

AVALANCHE PROBLEMS:

Storm Snow: More than five feet of new snow accumulated above 3500 feet elevation during the record setting storm May 2-5.

Wet Avalanches: With daytime warming, expect moist and wet snow avalanches off all aspects in the lower elevations and mid-elevations and, avalanches to run off southerly aspects at all elevations.

List of Avalanche Problems <here>

TRAVEL ADVISORY: Avoid avalanche terrain during the heat of the day, especially avalanche terrain exposed to direct solar radiation.

AVALANCHES: There was an impressive avalanche cycle May 4-5 with numerous large avalanches running to the valley bottoms. The 10 mile long Port of Valdez was full of debris, including trees. Avalanches running down Snowslide Gulch at Milepost 16 may have briefly blocked the Lowe River. There are avalanche crown lines to 10 feet deep.

Avalanches are sized using the destructive scale <here>

WEATHER: Becoming mostly sunny by Thursday and staying so until Sunday. Light winds. With temperatures warming to 50 degrees F Friday and Saturday, May 10-11, the weather is  looking good for the Valdez Fly-In and Air Show.

SNOWPACK DISCUSSION: Up to six feet of new snow accumulated above 3500 feet elevation during the May 2-5 storm. The storm snow sits over a variety of hard bed surfaces.

The overnight freeze Sunday May 5 made a thick crust over the moist snow in the mid elevation, decreasing the overnight avalanche danger significantly.

The freezing level during the storm fluctuated between just above sea level to an estimated elevation of 3500 feet. Temperatures at Thompson Pass reached 38 degrees F during the afternoon of May 5 triggering numerous avalanches.

However, the May 4-5 avalanche cycle did not affect much of the snowpack above 4000 feet and there still is a lot of storm snow available to avalanche off the mountain tops. Where the snowpack didn’t avalanche during the storm, sunshine will trigger an impressive cycle of new snow avalanches. The temperatures will start warming (finally) on Thursday May 9 and will mark the start of the spring shed.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated May 6:

CONFIDENCE: Fair.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet

Sunday to Wednesday, May 5-8, 2013

sunday	monday	tuesday & Wednesday
Danger Scale

DANGER TREND: The danger is increasing until the precipitation ceases. The danger will slowly decrease after the weekend. Watch for dramatic avalanche activitiy when the skies clear Monday triggering new snow avalanches through the week.

AVALANCHE PROBLEMS:

Storm Snow: More than four feet of new snowfall has accumulated above 3000 feet elevation since May 2nd.

Wet Avalanches: Numerous moist and wet snow avalanches are running off all aspects in the lower elevations and mid-elevations. Expect avalanches to run off southerly aspects at all elevations when the skies clear after Monday and the temperatures rise Friday.

List of Avalanche Problems <here>

TRAVEL ADVISORY: Avoid avalanche terrain. Expect easily triggered windslabs throughout the forecast period.

AVALANCHES: Widespread cycle of avalanche activity to size 3 across the forecast area May 4-5. The Port is full of debris and some trees. Avalanches ran to the valley bottoms.

Avalanches are sized using the destructive scale <here>

WEATHER: After the precipitation stops Sunday, sunny breaks Monday through Thursday. Light winds. Warming up Friday and looking good for the Valdez Fly-In and Air Show on May 11.

SNOWPACK DISCUSSION: More than 4 feet of new snow has accumulated in the upper elevations May 2-4 over a variety of hard bed surfaces. With the additional foot of snowfall before the storm ends on Sunday, natural slab avalanches are expected.

Where the snowpack didn’t avalanche during the storm, sunshine will trigger an impressive cycle of new snow avalanches.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated May 6:

CONFIDENCE: Fair.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet

Thursday to Saturday, May 2-4, 2013

thursday	friday	saturday
Danger Scale

DANGER TREND: The danger will increase to HIGH by Friday afternoon with the accumulation of lots of new snow and the rainfall below the freezing level snow line.

AVALANCHE PROBLEM:

Storm Snow: Three feet of new snowfall is expected by Sunday morning.

Wet Avalanches: Moist and wet snow avalanches are possible off all aspects in the lower, and progressively into the mid-elevations, and off southerly aspects at all elevations.

List of Avalanche Problems <here>

TRAVEL ADVISORY: Avoid avalanche terrain on Friday and through the weekend.

AVALANCHES: Size 3 off Mt Snowslide into Snowslide Gulch May 3. Limited observations.

Avalanches are sized using the destructive scale <here>

WEATHER: Up to 4 feet of new snow is expected to accumulate by Sunday above 2000 feet elevation, possibly lower, and as much as 4 inches of rain is expected to fall at sea level. The snow is being drifted by moderate southerly winds. Temperatures may stay unseasonably cold until the Valdez Fly-In and Air Show on May 11.

SNOWPACK DISCUSSION: The new snow is accumulating over a hard bed surface. New snow instabilities are expected Thursday. Natural point release avalanches are expected Friday. Natural slab avalanches are expected Saturday.

The snow in the lower elevations, and at all elevations exposed to solar radiation, are warming up. Rain introduces a lot of heat into the snowpack. Snowpacks heat up much faster than they cool down. New snow readily avalanches when exposed to rain. Although old snow can absorb a lot of rainfall before avalanching, the avalanches can be quite large.

The sunny breaks forecast for May 5-6 will trigger an impressive cycle of new snow avalanches.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated May 3:

CONFIDENCE: Fair.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet

Monday to Thursday, April 29 to May 2, 2013

monday	tuesday	wednesday & thursday
Danger Scale

DANGER TREND: The danger is steady. There is LOW danger while the snow is frozen in the morning. When the air temperature warms up during the day the snow looses strength increasing the avalanche danger to CONSIDERABLE or even HIGH after noon.

The danger will increase on Friday with the new snow and the warming temperatures.

AVALANCHE PROBLEM:

Wet Avalanches: Moist and wet snow avalanches are possible off all aspects in the lower, and progressively into the mid-elevations, and off southerly aspects at all elevations.

List of Avalanche Problems <here>

TRAVEL ADVISORY: Spring conditions mean that timing is everything. The same snow which is frozen concrete in the morning may become a quivering bowl of jelly when it thaws. Plan your route and avoid traveling under or on steep slopes later in the day, especially if they are exposed to direct solar radiation. Stay clear of cornices.

When wet snow starts to move, even small quantities can be quite dangerous. When moist-wet snow starts heading downhill, it can be impossible to not be trapped in it and many have been swept to their peril. Wet snow moves slow at first, but becomes destructive as it picks up mass and speed. If you get tipped over or knocked off your feet, where will you go? Avoid travel above terrain traps such as cliffs, rocky areas, and gullies.

AVALANCHES: There has been very little avalanche activity over the past few days with the unseasonably record setting cold weather since the skies cleared April 25 and the winds have been out of the north. One size 2 slab pulled out across the Lowe River at the mid-elevation on the north side of Abercrombie area at Milepost 5. One size 2 moist snow avalanche pulled out of the upper elevation above town.

The last cycle was solar triggered with the warm weather of April 22 and 23 when moist snow point releases of mostly new snow ran on southerly aspects to size 2.5 with the avalanches above Valdez terminating at sea level and a few avalanches at Mileposts 16 and 40.

Avalanches are sized using the destructive scale <here>

WEATHER: Becoming cloudy with a bit of snow starting Tuesday. The temperatures will begin moderating bringing rain showers to the lower elevations on Wednesday and Thursday. There may be one inch of rain in town on Friday. There may be as much as 16 inches of snowfall above the freezing level by Sunday.

SNOWPACK DISCUSSION: The snowpack is sculpted and scoured pencil to knife hard where wind affected. There is some firnspiegel (clear glassy ice lens on the surface of the snowpack where melted by sunlight).  There are new windslabs which were thought to have been deposited over weak faceted snow developed during the clear weather April 18-21 and buried under a few inches of new snow April 22-24, but, so far, there has been no evidence of reactivity.

The light snowfall starting Tuesday will accumulate on firm bed surfaces. The new snow will avalanche as soon as the sun hits it, possibly Sunday and Monday May 5-6.

With the record setting depth of snow on the ground at the end of April and the record setting cold weather, the snowpacks are remaining generally cold, well below freezing on aspects not warmed by the sun. However, it is anticipated the snowpacks will soon begin to warm up rapidly. When the air temperatures at the mountain tops finally reach 50 degrees F, we will see a widespread spring shed. The avalanche forecast varies dramatically according to aspect. Shaded north aspects are likely to remain good stability. Aspects warmed by the sun are likely to avalanche.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated May 1:

CONFIDENCE: Good.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet

Thursday to Sunday, April 25-28, 2013

thursday	friday	Saturday & sunday
Danger Scale

DANGER TREND: The danger is generally increasing with the onset of spring. Although the danger is LOW while the snow is frozen in the morning, as the air temperature warms up during the day the snow looses strength increasing avalanche danger to CONSIDERABLE or even HIGH after noon.

AVALANCHE PROBLEMS:

Wet Avalanches: Expect moist and wet loose snow avalanches off all aspects in the lower, and progressively into the mid-elevations, and off sun baked aspects at all elevations. These avalanches can become quite large and destructive if the terrain allows them to keep picking up more and more snow.

Wind Slabs: North winds to 70 mph Thursday into Friday will create new windslabs.

Avoid cornices.

When traveling on glaciers, know when you are, in fact, on a glacier. Do not stop on depressions, it could be a sagging snow bridge. Ensure the people you travel with have the gear and skills for crevasse rescue.

List of Avalanche Problems <here>

TRAVEL ADVISORY: Spring conditions mean that timing is everything. The same snow which is frozen concrete in the morning may become a quivering bowl of jelly when it thaws. Plan your route and avoid traveling under or on steep slopes later in the day, especially if they are exposed to direct solar radiation. Stay clear of cornices.

When wet snow starts to move, even small quantities can be quite dangerous. When moist-wet snow starts heading downhill, it can be impossible to not be trapped in it and many have been swept to their peril. Wet snow moves slow at first, but becomes destructive as it picks up mass and speed. If you get tipped over or knocked off your feet, where will you go? Avoid travel above terrain traps such as cliffs, rocky areas, and gullies.

AVALANCHES: Moist snow point releases of mostly new snow ran on southerly aspects on April 22 to size 2.5 with the avalanches above Valdez terminating at sea level. A few smaller point releases gouged old snow in the lower elevations off all aspects April 23. Also April 23, a number of size 2 point releases gouged old snow from the upper elevations on south aspects.

Avalanches are sized using the destructive scale <here>

WEATHER: Sunny days with some clouds overnight throughout the forecast period. Expect strong north winds to 70 mph on Thursday and into Friday. Lovely weekend. More snow (rain in town) next week.

SNOWPACK DISCUSSION: The new windslabs may be deposited over weak faceted snow developed during the clear weather April 18-21 and buried under a few inches of new snow April 22-24.

So far this spring the snowpacks have remained generally cold, well below freezing. However, the snowpacks are now warming up rapidly. When the air temperatures at the mountain tops warm up to 50 degrees F, we will see a widespread spring shed. Will that occur within the next few days? On one hand, clear days and cloudy nights create a greenhouse effect trapping the heat and preventing overnight long wave radiation cooling. On the other hand, wind over the surface of the snowpack both removes free water, decreasing weight, and provides substantial evaporative cooling.

Therefore, the avalanche forecast varies dramatically according to aspect. Shaded north aspects are likely to remain good stability. Aspects warmed by the sun are likely to avalanche.

Please contribute to the Snow Observations page. Photos and observations are welcomed.

SNOW and Precipitation updated April 24:

CONFIDENCE: Good.

DEFINITIONS: Forecast Areas:

• Below treeline – below 2000 feet
• Above treeline – above 2000 feet