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Isaias, now a tropical storm, barrels toward Florida before it surges up entire East Coast

The Washington Post logo The Washington Post 4 days ago Jason Samenow, Andrew Freedman, Matthew Cappucci
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Isaias is beginning a multiday assault on the U.S. East Coast with tropical storm conditions gradually developing over Florida on Saturday night, followed by hurricane conditions Sunday. The former hurricane was reclassified as a tropical storm by the National Hurricane Center in its 5 p.m. update but is forecast to regain hurricane strength Saturday night. As of 8 p.m., it was already showing signs of re-intensification.

The storm is then slated to ride up the entire East Coast later in the weekend into the middle of next week. It may unleash torrential rain, high winds and coastal flooding as far north as Maine.

Already, the Hurricane Center reports the storm’s outer bands have produced wind gusts of 40 to 60 mph in parts of southeast Florida.

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In Florida, hurricane warnings are in effect from Boca Raton to the Volusia-Flagler county line, which includes West Palm Beach, Jupiter, Vero Beach and Melbourne.

Fort Lauderdale is under a hurricane watch, but Isaias’s approach is expected to take it just far enough north that the city could escape the worst impacts.

Areas from the Volusia/Flagler county line to Ponte Vedra Beach are under a tropical storm warning while a tropical storm watch has been issued from north of Ponte Vedra Beach in Florida to the South Santee River in South Carolina, including Jacksonville, Fla., Simons Island, Ga., and Charleston.

Meanwhile, a storm surge watch covers the zone from Jupiter Inlet to Ponte Vedra Beach. The surge is the storm-driven rise in ocean water above normally dry land, which could lead to several feet of coastline inundation.

Since Friday, the storm has drenched the southeastern and central Bahamas, buffeting the islands with hurricane-force winds while also likely producing several feet of storm surge inundation. The Northwest Bahamas caught the brunt of Isaias on Saturday as it closed in on Florida where forecast models suggest the storm may make landfall Sunday.

Visualization of Hurricane Isaias near the Florida coast on Saturday night. (earth.nullschool.net) Visualization of Hurricane Isaias near the Florida coast on Saturday night. (earth.nullschool.net)

The tropical threat comes as the Sunshine State continues to grapple with a sharp increase in coronavirus cases.

Gov. Ron DeSantis (R) issued a state of emergency for counties along Florida’s Atlantic coast.

He said that the state and local communities are opening shelters while ensuring proper protocols be taken in the face of the pandemic.

North Carolina may also be hit hard by the storm from Monday into Tuesday, where Isaias could make a second landfall after slamming the Florida coast. A mandatory evacuation for Ocracoke Island has been ordered beginning at 6 a.m. Saturday.

Gov. Roy Cooper (D) issued a state of emergency and urged anyone who needs to evacuate to stay with family and friends or at a hotel, if possible, because of social distancing precautions at shelters. Shelters will provide personal protective equipment, Cooper said.

“With the right protection and sheltering, we can keep people safe from the storm while at the same time trying to avoid making the pandemic worse,” Cooper said via Twitter. “A hurricane during a pandemic is double trouble. But the state has been carefully preparing for this scenario.”

Other states, including Virginia, had also issued states of emergency ahead of the storm.

Isaias now and its track and intensity forecast

As of 8 p.m. Saturday, Isaias was located about 100 miles southeast of Fort Lauderdale, Fla., and was moving northwest at 9 mph. The storm’s maximum sustained winds had weakened from 75 to 70 mph, reclassifying it from a hurricane to a tropical storm.

Wind shear, or a change of wind speed and direction with height, along with dry air, continues to affect Hurricane Isaias, putting a lid on its intensity. However, the Hurricane Center expects the storm to restrengthen to a hurricane on approach to Florida as it passes over warm water. Towering thunderstorms erupted in part of the storm on Saturday evening, indicating it may be intensifying.

After the storm makes its closest approach to the Florida Peninsula, potentially making landfall early Sunday, slow weakening is predicted. On Monday, Isaias may drop back to strong tropical storm intensity as it departs Florida’s northeastern shores.

a close up of a map: Group of simulations from American (blue) and European (red) computer models from Saturday for Hurricane Isaias. Each color strand represents a different model simulation with slightly altered input data. Note that the strands are clustered together where the forecast track is most confident but diverge where the course of the storm is less certain. (StormVistaWxModels.com) Group of simulations from American (blue) and European (red) computer models from Saturday for Hurricane Isaias. Each color strand represents a different model simulation with slightly altered input data. Note that the strands are clustered together where the forecast track is most confident but diverge where the course of the storm is less certain. (StormVistaWxModels.com)

On its track up the East Coast and through the Gulf of Maine, the Hurricane Center calls for Isaias to persist as a strong tropical storm. The intensity forecast, however, is uncertain and depends on how much time the storm spends over the ocean, which is abnormally warm. Waters from the Mid-Atlantic southward are more than warm enough to support a hurricane.

While much warmer than normal, water temperatures north of the Mid-Atlantic would be expected to result in gradual weakening as Isaias passes through.

Impacts on Florida

a close up of a map: The National Hurricane Center's outlook for storm surge flooding associated with Isaias. Storm surge denotes the height to which water will inundate ordinarily dry ground. (NOAA/NHC) The National Hurricane Center's outlook for storm surge flooding associated with Isaias. Storm surge denotes the height to which water will inundate ordinarily dry ground. (NOAA/NHC)

Although Isaias is forecast to make its closest pass to Florida on Sunday, the storm’s outer rain bands have begun to affect southeastern Florida with heavy rains and strong winds.

Many models bring Isaias’s center far enough west that a landfall would occur in Florida on Sunday but it could also just scrape along the coast.

The Hurricane Center predicts a storm surge of two to four feet from Jupiter Inlet to Ponte Vedra Beach with one to three feet projected from north Miami Beach to Jupiter Inlet. The biggest surge is expected just north of where the center makes its closest approach to land.

There is the potential for life threatening storm surge along portions of the immediate coast that are typically vulnerable to elevated ocean levels or where dune erosion has occurred,” wrote the National Weather Service. “Low land flooding is also possible along the intracoastal waterways and in vulnerable low lands near inlets and other low areas near the coast.”

Damaging wind gusts up to 70 mph could occur along the Florida coastline if the storm makes landfall but would be somewhat less if the center stays offshore. If Isaias remains lopsided with the bulk of its winds east of the center, it’s likely winds in Florida could be limited to lower or midrange tropical storm force winds, sustained at greater than 39 mph.

The weather is behind NASA and SpaceX’s decision to bring the crew of SpaceX’s “Endeavor” capsule, which is slated to undock from the International Space Station on Saturday evening and splash down Sunday afternoon, for the first astronaut splashdown in the Gulf of Mexico, away from Isaias. The space agency and its private sector partner are aiming for a landing near Pensacola, where waves are forecast to be between one to two feet.

Heavy rainfall is predicted to unload a broad two to four inches with localized six-inch amounts in eastern Florida over the weekend. This could lead to “potentially life-threatening flash and urban flooding, especially in low-lying and poorly drained areas, across South to east-Central Florida,” the Hurricane Center wrote.

However, rainfall amounts in Florida will feature a steep gradient if the storm’s heaviest rains remain just offshore, in which case only a broad one to two inches with localized three-inch totals would be more likely.

Impacts from Georgia through the Carolinas and Virginia Tidewater

Sunday night through Monday, Isaias will parallel the coast of the southeastern United States and potentially make landfall in the eastern Carolinas late Monday.

Heavy rain and flooding, strong winds and storm surge are possible in coastal Georgia, South Carolina, eastern North Carolina and southeast Virginia.

The National Weather Service predicts two to four inches of rain and isolated amounts to seven inches in this zone, although a lesser one to three inches is favored in southeast Georgia with a more offshore storm track. Where the heaviest rain falls, isolated flash, river and/or urban flooding could occur.

a close up of a map: Forecast from Isaias through Wednesday from the National Weather Service. Forecast from Isaias through Wednesday from the National Weather Service.

Virginia to Maine

From the Delmarva Peninsula to coastal Maine, tropical storm conditions are also possible from Isaias between late Monday and Wednesday from south to north. This may include very heavy rainfall, strong winds, dangerous surf and coastal flooding.

Even areas somewhat inland from the coast, including the Interstate 95 corridor, could also see heavy rainfall depending on Isaias’s exact track.

The extremely moist air transported north by Isaias will also interact with a cold front preceding an approaching dip in the jet stream. That will help to focus the rainfall and will probably cause at least isolated flooding issues with up to six or seven inches of rain possible in a few locations, particularly in the Mid-Atlantic and along the Appalachians.

Storm sheltering during a pandemic

The ongoing coronavirus pandemic complicates the decisions both of local emergency management officials tasked with ordering evacuations and opening shelters, and the residents who may find themselves forced to use them.

On Thursday, the American Meteorological Society released guidance on sheltering during the pandemic, stressing that “if you evacuate to a shelter, you are responsible for your health.” The document notes, however, that states and municipalities that open shelters will most likely provide for social distancing and mask use, among other precautions.

They recommended that residents procure and bring their own sanitation supplies while also following Centers for Disease Control and Prevention recommendations.

The Federal Emergency Management Agency plans to rely less on deployed field teams in areas where community spread of the coronavirus is occurring, instead processing damage claims remotely. In addition, storm planning documents encourage officials to consider ordering those not vulnerable to storm surge or other flooding impacts to shelter in place.

Of the states most likely to be affected by the storm, Florida is among the hardest hit when it comes to coronavirus cases, hospitalizations and deaths. On Friday, Florida recorded its fourth consecutive day with a record high death count, at 257, along with 9,007 new cases. Florida is one of only four states to have had at least one day with more than 250 deaths, according to a Washington Post database.

In total, Florida has recorded 470,386 coronavirus cases, which is second only to California for the highest case load in the United States. It is also a higher number of cases than seen in many countries, including Italy, an early epicenter of the pandemic.

Impacts on Puerto Rico

On Wednesday and Thursday, Isaias blew through Puerto Rico as a gusty tropical storm, deluging the islands with significant flooding rainfall that caused damage. Doppler radar estimated up to eight inches fell.

The storm knocked power out to more than 400,000 residents on the island, and some 150,000 also lost water service for a time.

Isaias in historical perspective

Isaias became the ninth named Atlantic storm of 2020, which does not usually develop until closer to early October. It’s the earliest “I” storm on record by more than a week, and the latest domino to topple in a season that’s also brought the earliest-forming C, E, F and G storms on record in the Atlantic — Cristobal, Edouard, Fay and Gonzalo. Including Isaias, 2020 has produced five named storms in July, tied for the most on record with 2005.

It is the first time on record the last week of July has produced two hurricanes (Isaias and Hanna) in the Atlantic.

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