Snow Machine Rental

Hi I have a large backyard and would like to either rent or have someone come to my home in the bay area, ca to make some hills of "snow".. So my 10 yr old who is having a birthday can have a great experience w/ his friends snow sledding in the backyard..... The temp is maybe 40-60 degrees so it will have to be able to produce in "warmer" climates.
I need this for late April 2004.

Alex R.
Mill Valley, CA