Tropical Cyclone Report - National Hurricane Center - NOAA

Elsewhere, the following inundation levels, expressed above ground level, were prevalent
along the coast due to the storm tide:
Mississippi 5 – 9 ft
Alabama 3 – 5 ft
Florida (west and southeast coasts) 1 – 2 ft
Puerto Rico and US Virgin Islands 1 ft
Significant storm surge flooding occurred along the coasts of Mississippi and Alabama
(Fig. 9b). The highest water levels occurred in Hancock and Harrison Counties, Mississippi,
where several USGS storm tide pressure sensors suggested inundation depths of 5 to 9 ft above
ground level, and high-water marks indicated that the storm surge penetrated inland north of
Interstate 10. Measured water depths were as much as 6 ft farther east in Jackson County. In
Alabama, the maximum inundation occurred on Dauphin Island, where a USGS sensor measured
a water level of 4.5 ft above ground level. Data from other sensors suggested that water depths
were 1 to 3 ft along the shore of Mobile Bay.
In Florida, the highest storm surges recorded by NOS tide gauges were along the Florida
Panhandle and Apalachee Bay, with 3.47 ft above normal tide levels at Pensacola and 3.44 ft at
Apalachicola, resulting in inundation estimates of about 3 ft above ground level. Storm surge
measured by gauges along the west coast of Florida, the Florida Keys, and southeastern Florida
was generally 1 to 3 ft above normal tide levels, resulting in maximum inundation of 1 to 2 ft
above ground level.
Water levels rose no more than 1 to 1.5 ft above normal tide levels in Puerto Rico, the
U.S. Virgin Islands, and parts of the northern Leeward Islands, yielding maximum inundation
depths of about 1 ft above ground level near the immediate coast. The highest recorded storm
surge in these areas was 1.23 ft by a Puerto Rico Seismic Network sensor in Mayagüez.
Rainfall and Flooding
Isaac produced heavy rainfall across Puerto Rico and Hispaniola, causing flooded rivers
and mud slides. Much of the rain occurred after the center of Isaac passed the islands, as deep
tropical moisture from the south was forced up the south-facing slopes of the higher terrain. The
maximum measured rainfall total in Puerto Rico was 9.28 inches several miles north of Ponce on
the southern side of the island. The highest rainfall reported in the Dominican Republic was
16.18 inches in Barahona, on the southwestern coast of that country. No rainfall amounts are
available from Haiti. Heavy rain also occurred in eastern Cuba, with maximum amounts of
14.08 inches reported in San Antonio del Sur, Guantánamo, and 10.80 inches reported in El
Plátano, Granma.
Severe flooding occurred over parts of South Florida and East-Central Florida due to
heavy rains affecting the same areas for a prolonged period. The worst flooding occurred over
Palm Beach County to the west of Florida’s Turnpike in the communities of Wellington, Royal
Palm Beach, Loxahatchee, and the Acreage, where entire neighborhoods were isolated by several
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