Avalanche Advisory Archive Pre-2016

Date Issued:2012-01-31
Danger:4
Trend:3
Probability:4
Size:3
Problem:0
Discussion:

The National Weather Service Forecasts-

TODAY...RAIN. SNOW LEVEL 1000 FEET. HIGHS AROUND 38. SOUTHEAST
WIND 10 TO 15 MPH.

TONIGHT...RAIN. SNOW LEVEL 800 FEET DECREASING TO 400 FEET LATE. LOWS AROUND 33. SOUTHEAST WIND 10 MPH.

WEDNESDAY...CLOUDY. CHANCE OF RAIN. HIGHS AROUND 38. SOUTHEAST WIND 10 TO 15 MPH.

In the last 36 hours temperatures have risen by 8-10f degrees at Eaglecrest Summit and the Mt Roberst Tram Summit respectively.

Winds were from 10-20mph Sunday night into Monday afternoon out of the SSE and picked up last night around 4pm to 20-40mph out of the South.

We have received 37mm of precip overall since Sunday morning. 20MM of that coming through the day on Sunday then another 17mm of that in the last 24 hours. We received the last 10mm (.4\") of precip in the last 12 hours during the warmest part of our storm which was also accompanied by those high winds.

We are creating an upside down snowpack placing high density and wind driven snow on top of the looser lighter snows that were in place on Sunday.

With slight additional warming in the forecast for today and another .55\" of precip in the forecast for the next 24 hours at these warmer temperatures avalanche danger is HIGH at this time.

Potentially destructive natural avalanches likely to come near or reach developed areas,especially along Thane Road. We may also see natural avalanche activity in the White Path, as well as perhaps along the Flume and Perseverance Trail. The Berhands path is also a concern.

Thane Road will be closed from 10am to Noon as the DOT performs avalanche control. This will give us a better indication of the size and volume of avalanche potential should any other natural avalanches occur. THANK YOU DOT!

Natural and human triggered avalanches likely. Yesterdays field work showed that skier triggered avalanches were easy to create and with this additional windloading, warming, and continued precipitation throughout the day today this danger is continuing to increase.

As we start to dry out a little this afternoon and temperatures start to cool a little tonight danger will decrease slightly for a while. After 3pm tomorrow afternoon into Thursday the forecast calls for continued warm temperatures once again with over 1\" of precip in the forecast from Wed-Thurs... and again from Thursday into Friday... Avalanche danger will be high once again during that time.

Today is a great day to limit your exposure to avalanches by simply avoiding avalanche terrain.

Tip:

Upside-Down Storm:

Sometimes 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