Jacksonville flooding in 2017
Downtown Jacksonville on September 11, 2017, during Hurricane Irma. Irma's storm surge and rains brought the highest water level in modern records to the city. (Photo credit: Jacksonville Sheriff's Office)

The COVID-19 pandemic and anti-racism protests are already presenting challenges to Republican Party leaders planning the 2020 nominating convention in Jacksonville, Florida’s largest city. Add to that witch’s brew the calculation for a one in 50 chance a hurricane could cause major postponements or disruptions where the event will occur during a peak portion of hurricane season: August 24-27.

You might be willing to put a 10-spot down on something if the odds of losing are only 1 in 50. But if you were betting on something really important? Maybe not so fast. Plus, there’s some history to draw from.

In 2012, as that year’s Republican National Convention in Tampa Bay approached in late August, organizers cast a worried eye towards the Caribbean, where Tropical Storm Isaac was gathering strength. Isaac was predicted to intensify and take a track that could potentially threaten Tampa. Isaac ended up taking a track close enough to Florida to force a one-day delay in the convention, from August 26 to August 27, but it spared Florida a direct hit. The convention held its full set of events – except that a speech by then-Louisiana Gov. Bobby Jindal had to be canceled given Isaac’s impact on his state. The governors of Florida and Alabama also canceled their planned visits to the convention given the threat from the storm. Isaac ended up hitting Louisiana as a category 1 hurricane, killing 10 people and causing nearly $3 billion in damage in the U.S.

Figure 1. The August 24-27, 2020 Republican National Convention falls during the peak portion of the Atlantic hurricane season. (Image credit: NOAA/NHC)
Figure 2. Using data for the 111-year period ending in 2010, the average return period for a category 1 or stronger hurricane to pass within 58 miles of the coast near Jacksonville was once every 13 years. (Image credit: NOAA/NHC)

Jacksonville typically experiences less hurricane activity than other parts of the coast of Florida. Its position on a concave portion of coast, which does not stick out into the Atlantic, keeps the city from receiving many hurricane strikes. Statistics from the National Hurricane Center for the period 1900-2010 (Figure 2) reveal that the coast near Jacksonville on average can expect to see a hurricane pass within 58 miles (50 nautical miles) once every 13 years. That’s tied with the Big Bend region of the Florida Gulf Coast for lowest frequency of hurricane activity for coastal Florida. But a hurricane doesn’t have to pass close to the city to cause significant impacts. Three hurricanes in the past four years passing 60-120 miles from Jacksonville caused significant damage and/or evacuations in the city. Were another to occur during the 2020 Republican National Convention, major disruptions to or even cancelation of the convention might be necessary. Let’s review the three storms.

Figure 3. Tracks of all category 1 and stronger hurricanes since 1851 to pass within 120 miles of Jacksonville Beach, Florida. (Image credit: NOAA)

Hurricane Matthew, 2016

The coast from far northeast Florida to southern South Carolina is highly vulnerable to storm surge, as the offshore waters are very shallow and the concave shape of the coastline acts to funnel water onshore.

When Hurricane Matthew roared northwards just 60 miles offshore from Jacksonville on October 7, 2016, as a category 3 storm with 115 mph winds, evacuations were ordered for the entire northeastern coast of Florida in light of the storm surge threat. The powerful hurricane’s onshore winds drove the highest storm surge ever recorded to the Jacksonville coast: 3.22 feet above the high tide mark at Jacksonville’s Mayport Naval Air Station, where records date back to 1928. A post-storm survey found that storm surge heights as much as seven feet above ground level occurred about 50 miles south-southeast of Jacksonville. Widespread rainfall in excess of 10 inches caused significant flooding in the Jacksonville area, and Matthew’s tropical storm-force winds led to nearly 250,000 customers losing power. Damage to the region was estimated at over $175 million, with most of the damage occurring at the coast, stemming from storm surge.

Figure 4. Pass with caution! State Highway A1A in Flagler Beach, Florida (50 miles SSE of Jacksonville) in October 2016 after storm surge of Hurricane Matthew. (Photo credit: Florida Department of Environmental Protection)

Hurricane Irma, 2017

Just one year after Hurricane Matthew, Hurricane Irma nearly broke Matthew’s storm surge record.

After barreling into the Florida Keys as a category 4 storm, Irma on September 11, 2017, tracked up the west side of the Florida Peninsula, passing about 120 miles southwest of Jacksonville as a category 1 hurricane with 75 mph winds. The sprawling circulation of Irma extended well out into the Atlantic Ocean east of Jacksonville, and persistent onshore winds – sustained at 68 mph and gusting to 87 mph at Jacksonville’s Naval Air Station – drove a storm surge second only to Matthew’s to the coast.

A storm surge of nearly five feet rampaged up the St. Johns River into downtown Jacksonville, 10 miles inland, reaching about five feet high in some homes – the highest in modern recordkeeping, and a mark not seen since the Great Gale of 1846. Torrential rains of 10-15 inches exacerbated the flooding in the downtown area and in the Riverside and San Marco neighborhoods, sites of approximately 350 water rescues. Multiple tornadoes hit the coast near the city, and widespread power outages affected the Jacksonville region, with more than 330,000 customers losing power. Some outages lasted days. Total damage in Jacksonville from Irma was estimated at $85 million. Five deaths occurred in the region, three from cardiac arrest and two by drowning.

Figure 5. Single-family home destroyed in South Ponte Vedra, Florida (about 20 miles southeast of Jacksonville) by the storm surge of Hurricane Irma of 2017. (Photo credit: Florida Department of Environmental Protection)

Hurricane Dorian, 2019

Mother Nature gave Jacksonville a break from hurricanes in 2018, but in 2019, was back at it. After mauling the Bahamas as a category 5 storm, Hurricane Dorian turned north and threatened northeast Florida, forcing coastal evacuations once again.

Dorian passed about 120 miles east of Jacksonville on September 4, 2019, as a category 2 storm with 105 mph winds. A storm surge of nearly three feet occurred at the coast, but the highest surge occurred at low tide and caused only minor flooding. Dorian brought sustained tropical storm-force winds of approximately 40 mph to the coast, with weaker winds in inland parts of the city, resulting in sporadic and short-lived power outages to 32,000 customers. Damage to the city was minimal, and no deaths or injuries were reported.

Also see: ‘Stalled’ hurricanes like Dorian could become more common

Hurricane forecast for the 2020 Republican National Convention

Historical data suggest that a convention in Jacksonville during a four-day period in the peak part of hurricane season would likely experience disruption odds of 1-2% from a hurricane in any given year. According to forecasts from all of the major seasonal hurricane prediction groups, the 2020 hurricane season is expected to be a busy one, so let’s put the odds of a hurricane disrupting the 2020 Republican National Convention at the higher end of this range: 2%.

With those kinds of odds, convention planners likely would do well to keep a wary eye on the tropics.

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Jeff Masters

Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into category 5 Hurricane Hugo, he left the Hurricane Hunters to pursue a...