We tried the pressure washer method the other night and it would work except you need to be relatively high up like on your roof and it is hard to control the direction that the 'snow' will fall. We let ours sit on ground-level for about 15 min. and we had a start. The only problems are that you are going to use a lot of water and it will take mass time. I would say that at the rate we were going it would take about 6 hrs. to have something to work with. Also the 'snow' that it makes will be really difficult to shovel and move around. It will probably be more like ice than snow but definetly skiable. Another thing that real snow makers use is a bacteria called SnoMax.... It makes the water freeze at higher temps. and it makes the snow fluffier i believe.
Hope that kinda helps,
Later,
Tad
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Freezing Point 32°