It seems your oak almost BARBER CHAIRED, one of the most dangerous felling conditions. Since you are WA, where the forestry industry is large, get training. Ask about "The Game of Logging" or try ag extension agents, state occupational safety adm, adult education services, etc. Logging is one of most risky industries in the nation. A day in the woods with a chainsaw can rapidly progress from an outing to an adventure to an ordeal. Also check out the Forestry Forum. Be safe.