Hurricane Isaias track: Storm aims at Florida, North Carolina, New England

The Tropical Storm Watch from the Volusia/Flagler County Line to Ponte Vedra Beach Florida has been changed to a Tropical Storm Warning. A Tropical Storm Watch has been issued from north of Ponte Vedra Beach in Florida to Altamaha Sound in Georgia, including Simons Island, Ga., and Jacksonville, Fla.

In Florida, hurricane warnings have been hoisted from Boca Raton to the Volusia-Flagler county line. This includes places West Palm Beach, Jupiter, Vero Beach and Melbourne in the hurricane warning.

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

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 will contend with the brunt of Isaias on Saturday as it closes in on Florida where an extremely close shave or direct hit is possible Saturday night or Sunday.

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 covid-19 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. on Saturday.

Gov. Roy Cooper 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 11 a.m. Saturday, Isaias was making the first of what could be multiple landfalls, this time on northern Andros Island in the Bahamas. It was located about 40 miles west-southwest of Nassau and 135 miles south-southeast of Freeport on Grand Bahama Island. It had maximum sustained winds of 80 miles per hour, and was moving northwest at 12 mph.

Wind shear, or a change of wind speed and direction with height, continues to affect Hurricane Isaias, putting a lid on its intensity and affecting its distribution of winds. Hurricane force winds were found by early morning aircraft reconnaissance missions east of the center, but weaker winds were present on its western side.

However, the Hurricane Center expects the shear to be reduced between Saturday and Sunday, while the storm moves over the toasty waters of the Gulf Stream. This should allow Isaias to maintain hurricane intensity, and possibly to intensify a modest amount.

Weather radar from the Bahamas and Hurricane Hunter aircraft shows that dry air drawn into the storm had eroded the southern half of the eyewall, inhibiting Isaias’s strength. A full, circular eyewall containing the storm’s strongest winds and some of its heaviest rains is necessary for the hurricane to intensify significantly.

On satellite imagery, the bulk of Isaias’s shower and thunderstorm activity was largely to the north and east of the center, leaving the storm rather lopsided.

“Isaias has a somewhat ragged appearance in satellite imagery this morning, likely due to the impact of westerly shear and dry air entrainment,” the National Hurricane Center wrote.

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

On its track up the East Coast up 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

Although Isaias is forecast to make its closest pass to Florida Saturday night into Sunday, rain is expected to begin in southeast Florida by Saturday morning.

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

The Hurricane Center predicts a storm surge of 2 to 4 feet from Jupiter Inlet to Ponte Vedra Beach, Fla, with 1 to 3 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 could prove problematic for the crew of SpaceX’s “Endeavor” capsule, which is slated to undock from the International Space Station on Saturday evening and splash down in the waters off the coast of Florida on Sunday afternoon. While the weather east of Florida looks potentially treacherous, the crew could alternatively land in the Gulf of Mexico, away from Isaias.

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 walk a steep gradient if the storm’s heaviest rains remain just offshore, in which case only a broad 1 to 2 inches with localized 3 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 U.S. 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 6 inches in this zone, although a lesser 1 to 2 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.

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 6 inches or more of rain possible in a few locations, particularly in the Mid-Atlantic and along the Appalachians.

Storm sheltering during a pandemic

The ongoing covid-19 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 covid-19 pandemic, stressing “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 CDC recommendations.

The Federal Emergency Management Agency (FEMA) plans to rely less on deployed field teams in areas where community spread of covid-19 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 cases of covid-19, which is second only to California for the highest case load in the U.S. 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 in Puerto Rico. Doppler radar estimated up to eight inches fell.

Isaias in historical perspective

Isaias became the ninth named Atlantic storm of 2020, which doesn’t 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.

Another tropical wave off the coast of Africa became a depression on Friday night, but held just shy of tropical storm force. It was expected to dissipate on Saturday.

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