12 May 2013

May 12, 2013

Yesterday morning the clouds moved in but the rain held off until later in the day.

At 2240 meters the temperature was +1.5, winds were 60-100 KPH from the S. At 1550 meters the temperature was +6.5, 26 mm of rain was recorded there. The base sits at 140 cm. In the valley it was +12. Observations taken at 07:00 hrs this AM.

There is an Avalanche Closure in effect for the Alpine today!!

For the forecast the heavy precipitation associated with the frontal system has eased off for the time being but there is more rain on the way. We should see a lull for a while with increased precip again this evening. The long term forecast looks grey and wet for the week, as a series of week fronts move through our area.  An upper level trough is expected Monday afternoon and Thursday. Freezing levels will be around 2300 meters today, slowly lowering to 1700 meters by Tuesday night. The remainder of the week will see freezing levels between 2000-2300 meters. Guesstimates for Today 10-15 mm, Monday 10-15 mm, Tuesday 3-5 mm, Wednesday 3-5 mm, Thursday 3-5mm.

Melt-Induced Deformation in an Isothermal Snowpack: Montana State University

Isothermal=Rotten: Teton Gravity Research Forum

Avalanche conditions in Colorado: CAIC

Definition of a wet snow avalanche from Wikipedia:

Wet snow avalanches

In contrast to powder snow avalanches, wet snow avalanches are a low velocity suspension of snow and water, with the flow confined to the track surface (McClung, first edition 1999, page 108).[2] The low speed of travel is due to the friction between the sliding surface of the track and the water saturated flow. Despite the low speed of travel (~10–40 km/h), wet snow avalanches are capable of generating powerful destructive forces, due to the large mass, and density. The body of the flow of a wet snow avalanche can plough through soft snow, and can scour boulders, earth, trees, and other vegetation; leaving exposed, and often scored, ground in the avalanche track. Wet snow avalanches can be initiated from either loose snow releases, or slab releases, and only occur in snow packs that are water saturated and isothermally equilibrated to the melting point of water. The isothermal characteristic of wet snow avalanches has led to the secondary term of isothermal slides found in the literature (for example in Daffern, 1999, page 93).[4] At temperate latitudes wet snow avalanches are frequently associated with climatic avalanche cycles at the end of the winter season, when there is significant daytime warming.

For the most part it was a very grey day.

Some great looking clouds at times.

Yesterday morning prior to the thicker clouds.

Yesterday afternoon in the thick of it.

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