Will weekend cool front blow red tide back into Palm Beach County?

A trio of cool fronts — two past, one pending — could push a red tide that has menaced the Treasure Coast for two weeks back into Palm Beach County, but likely in low concentrations.

The National Oceanic and Atmospheric Administration’s forecast for harmful algae blooms had listed Palm Beach County clear of the toxic Karenia brevis bloom in a prediction late last week, but a Tuesday forecast shows the possibility of very low levels through Friday.

James Sullivan, executive director of Harbor Branch Oceanographic Institute in Fort Pierce, said this past weekend’s offshore winds from consecutive cold fronts pushed the algae away from Treasure Coast beaches.

Westerly winds, however, also tend to move water to the right, which could put red tide off Palm Beach County’s coast. Also, a north wind from a cold front expected late Friday into Saturday also could move water south, as well as a weak near-shore current flowing south.

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“It could start working its way down the coast from what happened this past weekend, but if we get more onshore winds it could blow it right back to shore,” Sullivan said. “It’s in the realm of possibility.”

Red tide, which was first confirmed in Palm Beach County on Oct. 1 by the Florida Fish and Wildlife Conservation Commission, had shut down beaches in Indian River and St. Lucie counties last week. Both counties said their beaches were open as of Wednesday. Fort Pierce Inlet State Park is also open after it was closed to swimming over the weekend.

The most recent test results in Palm Beach County have returned either negative or very low concentrations of Karenia brevis except in two tests taken Oct. 24 that came back with low concentrations. Those results, found at Lake Worth Beach and in the Intracoastal waterway near Indiantown Road, had less than 10,000 to 100,000 cells of Karenia brevis per liter — enough to cause respiratory concerns in people sensitive to red tide or with pre-existing conditions.

A NOAA forecast for Miami-Dade and Broward counties shows no red tide expected through Friday.

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Edward Davis, a harmful algae bloom analyst for NOAA, was skeptical wind shifts from the cold fronts could have more of an influence on red tide movement than the north-flowing Gulf Stream. He said a change in the algae bloom forecast for Palm Beach County likely was triggered by the possibility of easterly winds, which would blow the aerosolized toxins toward the coast.

“We still believe the net transport will continue to be north, so moving away from the Palm Beaches,” Davis said. “There is a counter current that runs right along the beaches, but as long as the cells are in the Gulf Stream, it would take a major disruption for them to move south.”

About 55 fish-kill reports were made to FWC in October in Palm Beach County, with the majority occurring between Oct. 1 and Oct. 7. There was also a report Monday of a dead Goliath Grouper in Lake Worth.

More than 40 reports of dead fish in St. Lucie and Indian River counties were also made this month.

None of the reports from the Treasure Coast or Palm Beach County included sharks, manatees or dolphins, such as what was seen on the west coast of the state over the summer.

Red tide typically shows up in late summer and fall on the Gulf Coast and lasts into February. The most recent outbreak began in October 2017. If it continues at high levels in the Gulf of Mexico, it could make its way into the Florida Current and Gulf Stream again.

“The most important thing for us to note is we can’t make a forecast more than three to five days in advance on whether or not Palm Beach County could get impacted again or what the severity level could be,” Davis said. “There’s nothing that suggests an immediate severe threat, but that’s why we update the forecast twice weekly.”

Gov. Rick Scott announced Wednesday the Florida Department of Environmental Protection is committing nearly $1.3 million in grants to east coast counties for red tide mitigation, including $500,000 to Palm Beach County.

 kmiller@pbpost.com

@KMillerWeather