Hurricane Irma’s expected landfall in the U.S. is approaching, and with winds at 130 miles per hour, experts say the storm could rip roofs off buildings and down power lines across several states.
Storm surge is the term used to describe rising ocean levels caused by hurricanes and tropical storms. According to National Geographic, high winds and atmospheric pressure combine to push seawater outward and up. Combined with a rising astronomical tide, this creates a storm tide, per the National Hurricane Center.
According to the Wall Street Journal, the storm surge for Irma is expected to be nine feet in Miami, though as the storm appears to move more west, the Gulf Coast region could see a surge of up to 20 feet. The National Hurricane Center has released interactive maps showing every area under storm surge warnings and areas where more than nine feet of rising water is expected.
Storm surge can occur rapidly and is often responsible for most of the flooding in a hurricane, according to the National Ocean Service. Areas that are at or close to sea level are all at risk.
Unfortuantely, experts say once a storm strikes there is little homeowners can do to protect their houses from the surge except for sandbags, sump pumps and windows and doors that can resist rushing water.
Much of the defense against storm surge occurs before a storm strikes, according to experts. FEMA provides maps that assess areas’ chances of storm surge, and affected homes should have flooding insurance, officials say. Scientists also say that restoring natural wetlands can act as a natural buffer against storm surges in the future.
In the case of Irma, the surge does not even take into consideration the rainfall the storm will cause. According to the National Hurricane Center, however, the amount of rain is expected to be far less severe than it was in Hurricane Harvey.
While Harvey caused extensive flooding and damage because of the record-shattering amount of water the storm dumped on coastal Texas, Irma is projected to have less rain. The National Hurricane Center projects most of southern Florida to receive somewhere between 10 and 20 inches over five days, from Saturday to Thursday. Over four days, areas near Houston received nearly 50 inches of rain from Harvey.
While the storm surge is still projected to be dangerous in south Florida, including Miami, and high winds will likely cause damage as well, one expert who projected Harvey’s rainfall onto Florida predicted that, hypothetically, nearly all of five counties near Miami would be completely underwater at a depth of at least 10 inches if the area received 40 inches of rain. The National Hurricane Center does not project that level of flooding for Irma.