Avalanche Advisory Archive 2016 – 2018

Date Issued:2017-02-10 06:41:12
Danger:1
Primary Trend:3
Primary Probability:3
Primary Likelihood:1
Primary Size:2
Primary Description:

Here it comes... over the next 24 hours as the snow event kicks off things will start to rapidly change.

Todays forecast calls for as much as 4-6\" over the next 24 hours. This should remain fairly cold snow.

This cold snow is coming to rest on a bed surface that is age and wind hardened for the most part and shows faceting in places. This new snow will not bond well to the old snow surface.

Tomorrow things start to change for the worse. Temperatures will climb significantly. The forecast calls for temps to rise as much as 11f from today into tomorrow. Then tomorrow as we warm up through the point of freezing we will have VERY HIGH precipitation volumes.

Look to see temps rise from 32 to 38 through the middle of the day tomorrow with another 2\" of rain in the forecast for the day... starting in snow on top of the cold snow... then getting wetter and wetter turning into rain.

My guess is we will see a widespread natural avalanche cycle through the day tomorrow and tomorrow night.

Use caution out there tomorrow my friends. Safe lines and ENJOY>>>

Secondary Trend:3
Secondary Probability:2
Secondary Likelihood:1
Secondary Size:2
Secondary Description:

Here it comes... over the next 24 hours as the snow event kicks off things will start to rapidly change.

Todays forecast calls for as much as 4-6\" over the next 24 hours. This should remain fairly cold snow.

This cold snow is coming to rest on a bed surface that is age and wind hardened for the most part and shows faceting in places. This new snow will not bond well to the old snow surface.

Tomorrow things start to change for the worse. Temperatures will climb significantly. The forecast calls for temps to rise as much as 11f from today into tomorrow. Then tomorrow as we warm up through the point of freezing we will have VERY HIGH precipitation volumes.

Look to see temps rise from 32 to 38 through the middle of the day tomorrow with another 2\" of rain in the forecast for the day... starting in snow on top of the cold snow... then getting wetter and wetter turning into rain.

My guess is we will see a widespread natural avalanche cycle through the day tomorrow and tomorrow night.

Use caution out there tomorrow my friends. Safe lines and ENJOY>>>

Discussion:

The National Weather Service Forecasts-

Today- Widespread snow showers. Snow accumulation 2 to 4 inches. Highs around 29. Southeast wind 10 to 20 mph.

Tonight- Widespread snow showers. Widespread rain showers late. Snow accumulation 3 to 5 inches. Lows around 28. Southeast wind 10 to 20 mph.

Saturday- Windy. Not as cold. Snow in the morning. Rain...heavy at times . Snow accumulation to 2 inches...except 4 to 11 inches on douglas island above 1200 feet. Snow level 500 feet increasing to 1200 feet in the afternoon. Highs around 41. Southeast wind 25 to 35 mph with gusts to around 50 mph.

Temps remain cold around the region this morning. The Tram is at 22f. Eaglecrest is showing 23f at the bottom, 17f mid mountain and 16f on top.

Winds remain calm around the region but will increase as the snows turn on later today.

We have not seen any new snow in over 12 days which has given the snowpack ample time to strengthen.

Look at the two problems below... one for today and one for tomorrow... things are going to get interesting.

I hope you get out early tomorrow and play it safe. Avalanche danger is greatly on the rise during this storm.

I expect we will see a widespread natural avalanche cycle tomorrow afternoon. Be Safe Out There.

Tip:

Upside-Down Storm

When a snowstorm deposits denser snow over less dense snow, creating a slab/weak layer combination.

Upside-Down Storm:

Quite often in Southeast Alaska snowstorms deposit denser, stiffer snow on top of softer, fluffier snow. We call this ?upside down? snow. We often call it ?slabby? or ?punchy? meaning that you punch through the surface slab into the softer snow below, making for difficult riding and trail breaking conditions. It also means that we need to carefully monitor avalanche conditions within the new snow because?by definition?a denser slab has been recently deposited on top of a weaker layer, which should make anyone?s avalanche antennae stand at attention. Most instabilities within upside-down snow stabilize within a day or two.

The kind of weather conditions that often produce upside-down snow include warm fronts, storms in which the wind blows harder at the end of the storm than the beginning, or storms that end with an unstable airmass, which can precipitate a lot of graupel within instability showers.

Forecaster:Tom Mattice