There are a few hackathons that are organized in the greater Portland area. The majority are devops and gamedev centric; meaning, if your particular discipline isn't in software programming, say instead you are focused on graphic design, marketing, finance, project management, human resources or office management, these might not be as easy to create a minimum viable product within the allotment of time.
Perhaps one of the many goals of why hackathons exist in Portland is to bring like minded people together to build something new from scratch. The hardest part is a viable idea that a team of 2-6 people can collaborate upon and present to a large group of strangers for mass public appeal.
For new organizers, there are two guides that I know of:
[The Book of Hackathon] (http://guide.mlh.io)
[The Hackathon Guide] (https://hackathon.guide/) by Joshua Tauberer
Not a definitive list, but a starting point for 2016.
Portland Area Hackathons
Global Game Jam: Portland 2016
Dates: Jan 29-31, 2016 #free
Details: http://bit.ly/1lpFzLo rsvp restriction age 18+
Theme: Game Coding
Startup Weekend Vancouver
Dates: Jan 29-31, 2016 #fee $85/participant
Details: http://bit.ly/1OAWFAm
Theme: Brainstorming, Pitches, Business Plan, Basic Prototype (minimum viable product)
Hack the Dot
Dates: Feb 4, 2016 #free
Details: http://bit.ly/1OAWuoE
Theme: Design a concept around a domain name
CodeDay Portland
Dates: Feb 13-14, 2016 #free
Details: https://codeday.org/portland rsvps for high school or college students only -no professionals-
Theme: App or Game Coding
ProtoHack Portland
Dates: Feb 20, 2016 at 9:30am #free
Location: DeskHub
Details: http://protohack.org/events/protohack-portland/
Theme: 12-hour prototype code-free hackathon for non-technical entrepreneurs
Monitorama
Dates: Jun 27-29, 2016
Location: Gerding Theater at the Armory
Details: http://monitorama.com/
Theme: Open Source Monitoring Conference & Hackathon