Saffir-Simpson Hurricane Wind Scale is undergoing changes this year | Weather

SACRAMENTO, CA    The long standing way to categorize hurricane strength is undergoing changes.

Scientists at the National Hurricane Center (NHC) analyzed how wind speeds were converted among the various units, such as knots to miles per hour. They realized there were some gray areas where conversions weren't as specific as they needed. This prompted them to develop a revised scale that better assess wind speeds for advisory products.

The changes will affect the Category 4 storms wind speed range, which will now be 130-156 m.p.h. Previously, the range was 131-155 m.p.h. winds. the NHC says historical records will not be altered based on this change.

Hurricanes start as tropical storms. Once wind speeds reach 74 m.p.h., the storms are classified as hurricanes. The Saffir-Simpson Hurricane Wind Scale ranges from Category 1 with winds 74-95 m.p.h. to Category 5 with winds 157 m.p.h. or higher.

More information on the modifications can be found on the National Hurricane Center website: http://www.nhc.noaa.gov/aboutsshws.php