I strongly disagree with my colleagues. Most misdemeanor warrants do not go into the NCIC information system. Only those considered "serious" do. See the following categories of people that NCIC collects information on: http://www.fas.org/irp/agency/doj/fbi/is/ncic.htm. The average misdemeanant is not among them.
Yes, a misdemeanor warrant is important enough to put into the national database so if you get stopped in another state near or far from Washington State, they will know you are wanted for failing to appear and can arrest you on the Washington State warrant. The problem will be if you are too far away, Washington State may not spend the money to come get you and so you'll be arrested, held and then released after a short period of days.
Yes, your misdemeanor warrant may be entered into the NCIC database. If you are contacted by California law enforcement, they can arrest you for this warrant. They must then contact the issuing agency and that agency must decide if it is worth it to them to send their personnel out-of-state to take custody of you and return you to Washington. You may also challenge extradition with local counsel although this is rarely a successful plan.
The simplest thing to do is to deal with the Washington matter. Otherwise, you will forever be looking over your shoulder and it will likely prevent you from ever having a valid driver's license.
Best of luck to you.
No answer here should be considered to form an attorney-client relationship. You should consult with a licensed attorney in your jurisdiction so that a full evaluation of the facts of your case can be conducted.