Does Washington extradite on felony warrants?

Not familiar with the classification of "gross" misdemeanor however, all US states and territories honor each other's requests for extradition - there are no 'safe-haven' states - It is impossible to know with certainty whether a particular state will choose to extradite you for a particular offense, or not, there are simply too many variables. It may depend, in part, on the offense and the seriousness of it, and/or how badly they want you returned - most states WILL extradite for felony offenses.

ADDITIONAL:

Overall the answer above is correct with the exception of 'safe haven': Oklahoma will not honor most misdemeanor warrants from Texas; likewise Texas does not honor warrants from Oklahoma - and neither state will arrest or hold you for those warrants issued in the other state or honor a request for extradition for these types of warrants (there seems to be a disagreement over fee's involved). Texas has a (unpublished and unadvertised) *general* 8 hour rule; if you are arrested the issuing authority is contacted and they have 8 hours to confirm extradition (start the paperwork and inter-county extradition) on any misdemeanor C; the third time a person is arrested and they don't extradite the warrant is rejected inter-system (vanishes).