Tenancy by the entirety or entireties probably no longer exists in Washington State, but it is unclear because of both history and some statutes that do not specifically answer your question. However, by statute there is no survivorship right under tenancy by entirety. You need to look at your deed to see what is actually says. If is does say the you hold title by tenancy by entirety or entireties, you should consider doing a new deed that makes it joint tenancy with right of survivorship.
Because you have a loan that is secured against the property, you probably would violate its terms if you change the way you hold the property. I suggest that you see a real estate lawyer to assist you with this.
Technically there is "Tenancy by the entirety" in the state of Washington. However, the property will not automatically pass to the survivor. If the bank insists on "Tenancy by the entirety" you and your wife will still have legal title to the real estate. You will have to make provisions for the death of one of you, for example by will or community property agreement. Such an insistence on taking title this way is an example of the inflexibility and incompetence of lenders. Even if Washington recogized succession by the entirety, this is an estate planning tool. Banks should not force estate planning on their customers. As stated, there is no harm to you and you wife by taking title as "Tenants of the entirety." You should discuss your estate planning options with an attorney.