Your caterpillar appears to be one of the earlier instars of a Silkmoth in the genus Hyalophora.    From Wordnik.com.  [What's That Bug?] Reference

It appears to be Hyalophora kasloensis which may be a self sustaining hybrid of H. euryalus and H. columbia gloveri.    From Wordnik.com.  [What's That Bug?] Reference

We believe this may be the third instar of either the Ceanothus Silkmoth, Hyalophora euryalus, or perhaps Glovers Silkmoth, Hyalophora columbia gloveri, or perhaps another species without a common name, Hyalophora kasloensis.    From Wordnik.com.  [What's That Bug?] Reference

( '' Hyalophora cecropia '').    From Wordnik.com.  [CreationWiki - Recent changes [en]] Reference

You could safely call it Hyalophora kasloensis.    From Wordnik.com.  [What's That Bug?] Reference