Can a mother leave WA with her child, with no parenting plan without notifying the father?

The answer depends on many things: are you and the father married? If so, is there a divorce case pending? If so, is there an emergency court order entered about custody? If not married, did you and the father file an Acknowledgement of Parentage? If not, did you or the state file a Petition to Determine Parentage? If so, has the Court entered an order? Whether or not any other case was filed, is there a history of domestic violence? The list of questions is very long. You should consult with an experienced family law attorney, who can then give you your realistic options. DISCLAIMER: This Answer is provided for general educational purposes only. By using or participating in this site you agree and understand that there is no attorney client relationship between you and the attorney responding, and no attorney-client confidentiality. The law changes frequently, and varies from jurisdiction to jurisdiction. The information provided in this Answer is general in nature and may not apply to the factual circumstances described in your question. The applicable law and the appropriate answer may be different in the State or States where the relevant facts occurred. For a definitive answer you should seek legal advice from an attorney who (1) is licensed to practice in the state which has jurisdiction; (2) has experience in the area of law you are asking about, and (3) has been retained as your attorney for representation or consultation. Your question and the attorney’s answer may be used for promotional or educational purposes.

The above answer is correct, this depends on the specifics about your case. Generally however, if there is no parenting plan or pending case, or emergency order in place, the court has no authority to tell you that you cannot move out of state.

I concur with Mr. Clement's opinion. Feel free to schedule an appointment to meet with me to discuss your case. Free, no obligation consultation. Jack Berner