KEY MESSAGES:
1. Matthew is likely to produce devastating impacts from storm
surge, extreme winds, and heavy rains in the northwestern Bahamas
today, and along extensive portions of the east coast of Florida
tonight.
2. Evacuations are not just a coastal event. Strong winds will
occur well inland from the coast, and residents of mobile
homes under evacuation orders are urged to heed those orders.
3. Hurricane winds increase very rapidly with height, and residents
of high-rise buildings are at particular risk of strong winds. Winds
at the top of a 30-story building will average one Saffir-Simpson
category higher than the winds near the surface.
4. When a hurricane is forecast to take a track roughly parallel
to a coastline, as Matthew is forecast to do from Florida through
South Carolina, it becomes very difficult to specify impacts at
any one location. Only a small deviation of the track
to the left of the NHC forecast could bring the core of a major
hurricane onshore within the hurricane warning area in Florida and
Georgia. Modest deviations to the right could keep much of the
hurricane-force winds offshore. Similarly large variations in
impacts are possible in the hurricane watch and warning areas in
northeast Georgia and South Carolina.
5. The National Hurricane Center is issuing Potential Storm Surge
Flooding Maps, and Prototype Storm Surge Watch/Warning Graphics for
Matthew. It is important to remember that the Potential Storm Surge
Flooding Map does not represent a forecast of expected inundation,
but rather depicts a reasonable worst-case scenario - the amount of
inundation that has a 10 percent chance of being exceeded. In
addition, because the Flooding Map is based on inputs that extend
out only to about 72 hours, it best represents the flooding
potential in those locations within the watch and warning areas in
Florida and Georgia.
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