A team with the National Weather Service traveled to Port Orchard to evaluate the damage from the tornado that formed Tuesday afternoon.
The team assessed the path of the tornado, the width of damage, and spoke with witnesses, among other things.
The Enhanced Fujita Scale (EF Scale) is used to issue a tornado rating based on estimated wind speeds and damage. The NWS looks at the path, width, duration, witness photos/videos, and past radar to come up with an overall rating.
The NWS is the only federal agency with authority to provide official EF Scale ratings.
The EF Scale was revised in 2007 from the original Fujita Scale. There were several weaknesses with the original scale. The new scale takes into account how most structures are designed, instead of simply taking into account damage done.
The wind speed ranges from 65 mph (EF0) to over 200 mph (EF5).
The tornado that swept through Port Orchard Tuesday was rated as an EF-2 with wind speeds reaching between 120-130 mph, according to a preliminary damage report.
The EF Scale is different than the Saffir-Simpson Scale used to categorize hurricanes. The wind speeds are used to determine the magnitude of the tornado (not necessarily the overall rating).