30" of snow lost in 21hrs @ Snoqualmie?

I'll get some densities later today when we work through the numbers, but it looks like the Snotel is right on track.

We also utilize a snow lysimeter that allows us to measure the outflow form a sample of the snow pack. A quick glance last night looked like we received 10"+ precipitation and around 3.5" of water left the snow once drain channels were established. Not too surprising considering the dry snow we had.

I'll run through those numbers as well.

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What about melting due to the actual warm air temperature? Again, air has a very hard time melting snow, even more so than rain because the heat capacity of air is about 4.2 times less than that of water. Therefore 4.2 times as much mass of air is needed to perform the same melting as a given mass of water. So melting a kilogram of snow using air at 5 degC (41 degF) would require 66 kilograms of it (330/5), which is a volume of about 55 cubic meters (almost 2000 cu ft), or the volume of a 12 x 20 ft room with 8 ft ceilings. And all that air would be cooled right to 0 degC in the process of melting 1 measly kilogram of snow. It's easy to see why strong winds are key to melting snow rapidly, because you've got to keep a continual fresh supply of 40 degF air coming through if you're going to melt any significant snow. With calm winds, the air right above the snow is quickly cooled to 0 degC, and it just sits there, incapable of melting any snow at all. The warmer air farther above is insulated from the snow by the denser now-cooled air, and without wind (or solar heating) the cold dense air can't move out of the way.

But what about the heat of condensation when the water vapor in moist, warm air condenses on cold snow? If condensation is possible, that should be a much bigger transfer of heat than conduction. And if I understand what the dew point signifies, if the dew point is above freezing then condensation on the snow will be occurring?

And is that an African swallow, or an European swallow? Laden or unladen? How would it grip the coconut, by the husk?

Amar's post was sure helpful.
For the area east of the pass check out Larry R's website for Sasse Ridge snowpack and weather, more graphs etc
www.larryscascaderesource.com/
Jane

And is that an African swallow, or an European swallow?  Laden or unladen?  How would it grip the coconut, by the husk?

Ha Ha, very funny. I love Monty Python.
But seriously I am in awe of Amar's post. We got some serious bad ass snow experts on this web site!

Here is a cool breakdown of the various mechanisms of snowmelt and their relative effectiveness:

www.cnrfc.noaa.gov/publications/Rain_on_snow.ppt