The National Weather Service Forecasts-

TODAY...RAIN AND SNOW. SNOW ACCUMULATION UP TO 2 INCHES. HIGHS
AROUND 35. SOUTHEAST WIND 10 MPH.

TONIGHT...RAIN. LOWS AROUND 34. SOUTHEAST WIND 10 TO 15 MPH.

THURSDAY...RAIN...HEAVY AT TIMES. HIGHS AROUND 41. SOUTHEAST
WIND 10 TO 15 MPH.

Over the last 40 hours we had received a nice little winter storm front.

Temperature, although cold during the beginning of the storm warmed up quite a bit throughout. Temps climbed by an average of 8f degrees during the storm and are now right at 30f at the Mt Roberts Tram summit and slightly colder at the Eaglecrest Summit. This is a considerable warming trend for during a storm period over that period of time.

We had considerable to high winds during the storm. Summit winds reached speads from 35 to 55 knots during the storm for over 8 hours. We had notable sustained winds from 20-35knots along the channel for most of the storm. Winds were primarily out of our SSE typical pattern yet towards the end of the storm they rolled to the South followed by SW for a period of time. You can assume anything with a north facing aspect to it will have some degree of windloading.

We received 30mm of precip during this 40 hour cycle. The first 15mm of precip left 30cm of very low density snow. The last 15mm of precip did not add to the overall height of snow total. You can assume this placed a tremendous load on the current snowpack primarily from the top... weighing down the upper layers while the lower layers remained somewhat lighter. This often creates an upside down snowpack placing heavy dense snow on top of the looser lighter snow in place that we started with. This often creates a concern as it is only a matter of time before these upside down snowpacks fail and settle. Sometimes in place, and sometimes in the vertical plane in the form of an avalanche.

Of greater concern is that this upside down snowpack came to rest on. Before the beginning of the new snow on Monday we had a faceted snow surface that often does not bond well to or support this new snow load that is being placed on it.

Under this layer of facets along the channel in the urban enviroment last week we were experiencing several weak layers deeper down in the snowpack. Some of which were being easily skier triggered as recently as last Thursday. Our concern is that these deeper week layers could become reactive under the load of this new snow. Our worst case scenario right now in the urban enviroments could be slabs of up to a meter in depth.

Yesterday we nearly reached a wide spread natural avalanche cycle. We had multiple natural avalanches reported in the area. Mostly mid-sized avalanches. But the storm intensity and warming slowed just in time to prevent a wider spread natural event.

The snowpack has stabilized somewhat over the last 24 hours but remains quite weak in places. During today into this evening we predict as much as .42' of additional precip before 6pm. Then the skies open up... From tonight at 6pm to Thursday AM at 6 the forecast calls for 1.04\" of precip. Then from 6am tomorrow to 6pm tomorrow the forecast calls for an additional 1.09\". and if 2.14\" of rain in 24 hours wasnt enough for you... Mother nature decided to add an additional 1.2\" of rain over the next 12 hours... So in total our forecast calls for 3.76\" of precip over the next 48 hours. This should create widespread natural avalanches if this forecast materializes.

Avalanche danger is CONSIDERABLE at this time and INCREASING GREATLY overnight tonight through tomorrow. Sometime tonight as the precip increases avalanche danger will transition to high.

At the current time Natural avalanches possible, potentially destructive avalanches may come near or reach developed areas.

Human triggered avalanches probable, especially in windloaded areas near summit and ridgeline. Also be careful around terrain traps and unsupported slopes. Yesterday human triggered avalanches were quite common and will continue to be fairly widespread today as well.

As we go into this evening and precip levels pick up the danger will transition to HIGH. At that time, Potentially destructive natural avalanches likely to come near or reach developed areas, natural and human triggered avalanches likely.

Today is a great day to avoid spending time in the avalanche paths up the Flume and Perseverance Trails. I would recommend avoiding these slopes for the next 48+ hours.

Danger in Thane Road is Considerable today and climbing. I was told last night that DOT is planning a mitigation shoot for there this morning. Great job DOT on being proactive to bring down some of this load before we see the next 3+\" of precip during warming.

Results of todays shoot should give us a better idea of size of the avalanche potential as we head into the next two days of HIGH danger.

Here is a great link to an article on a snowmobile triggered avalanche. Some good things to think about as take aways...

http://vimeo.com/38078462