Report shows Hurricane Irma was forecast better than others

Wind intensity reevaluated lower by National Hurricane Center experts

By Mark Collins - Meteorologist
NOAA National Environmental Satellite

JACKSONVILLE, Fla. - Report shows Hurricane Irma was fifth most expensive hurricane and half of Florida's casualties were in Duval county.

NHC forecasters said errors in predicting Irma’s track and strength were between 30 and 40 percent lower than average over the past five years.   

Irma caused widespread devastation and was the strongest hurricane on record in the Atlantic basin outside of the western Caribbean and Gulf of Mexico when its pressure dropped to 914 mb.

A new report from the National Hurricane Center adjusted peak winds in Hurricane Irma down to 178 mph which is 5 mph less than estimates gathered during a hurricane reconnaissance flight. 

Disparity between winds measured at the ocean surface and flight level brought the adjustment down but Irma remains one of the most expensive and destructive hurricanes on record.

The report ranked Irma as the fifth-costliest hurricane to affect the U.S., with damage estimated at $50 billion. Irma comes in behind Katrina in 2005, two other 2017 storms, Harvey and Maria, and Sandy in 2012.

Irma caused 44 direct deaths with seven of those occurring in the United States. In total, Florida had four deaths with two occurring in Duval County. Both a 59-year-old male and a 54-year-old female drowned after fresh water flooded their tent while camping in the woods.

Northeast Florida had significant storm surge even after Irma was downgraded to a tropical storm when it passed through north Florida.

As it made landfall in southwest Florida, a large wind field produced storm surge reaching 
4.8 ft above mean high water (MHHW) along the Matanzas River south of St. Augustine.

The USGS surveyed several high water marks of 2 to 4 ft above ground level in that area. The highest was a mark of 3.3 ft above ground level near Vilano Beach.

Jacksonville Beach recorded a water level of 6.55 ft above the ground or 4.1 ft above high mean tide. which was a bit larger than both Mayport and Fernandina Beach which peaked at 3.6 ft MHHW.

Irma moved across north-central Florida through early 11 September and then moved into
southeastern Georgia late that day and early 12 September spreading tropical storm force winds across the First Coast.

The highest sustained wind reached 58 mph at Jacksonville International, with gusts of 86 mph and a 87 mph gust in Mayport.

Flooding occurred on most rivers in northern Florida, and major or record flood stages were reported at rivers in Bradford, Clay, Marion, Flagler, Duval, Putnam, St. Johns, Nassau, and Alachua counties. The St. John’s River set record flood stages at many locations in Duval County, causing major flooding in the Jacksonville metropolitan area, where hundreds of people were rescued.

Similar flooding occurred in Bradford County where record flood stages were set at Alligator Creek, Hampton Lake, Lake Sampson, and New River. 

Irma created more than 21 tornadoes that twisted across Florida largely occurring along the east coast of central and northern Florida.

 

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