There are days where the mountains in Wa get 3-4 feet of powder. (they steal it from Oregon..

There are many groomed trails where your sled will be appropriate, but if you want to play in the hills, you definitely need a longer track with a deeper lug. On those days of unlimited powder, a 151" will seem short, and you can't have enough horsepower. Seattle gets a TON of moisture, mostly rain, but the snow is not far to drive to.
You will find a lot of guys running AC Mountain Cats and Polaris RMK's, Ski-doo is also pretty popular. The serious hillclimbers will have 159" to 166" tracks with lots of mods to the engine to get the HP to keep it turning. A stock 800 will do very well until your skill level increases. The Polaris Dragon 600 or 700 may be a really good choice; the sled has nice power and is light and turns nicely. It's a different skill set that needs to be learned, be prepared to get stuck a lot, buy the right tools... a shovel is a must, and an avalanche beacon and a probe should be on your wish list as well. Washington's web page is very well done, you should be able to see all you need to see to start drooling!
Welcome to the West!
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Rebuilding the fleet!
2008 RMK 600 155", 2006 RMK 600 144", 98 Indy 440, 95 Prowler 550 2-up, 1990 Indy 650
RIP, destroyed by fire 1-22-2008

04 RMK 800, 05 RMK 600, 02 RMK 800, 97 RMK 700