Andrea wasn’t big, and wasn’t bad, and wasn’t here.
That’s a hard sell for the dozens of Acreage residents slammed by a tornado Thursday, but it’s the case.
How can a weak tropical system so far away bring such destruction?
It’s all about that front-right quadrant.
And that’s why it’s a mistake for South Floridians not to worry about tropical cyclones until after those monsters start boiling up off the African coast in August and September. Those early- and late-season storms are dangerous, too.
Those that form in the Gulf of Mexico often move northeast and across the Florida peninsula, bringing that area under the storm’s front-right quadrant, its most powerful part. And that can mean heavy rainfall, or tornadoes or other wind events.
The calm first two months of hurricane season is a period forecasters sometimes call the “preseason.” It averages one hurricane every other year. The most likely starting points are the western Caribbean and the Gulf of Mexico.
“Those are the most-favored areas for development because the water temperatures in the early part of the season are warm enough, and the rest of the Atlantic basin is still not there yet,” National Hurricane Center spokesman Dennis Feltgen said Friday.
The height of the season comes because storms feed on warm water, and water is at its warmest in August and September. Also, wind shear — the difference between high and low winds, which tends to sap storms’ strength — is at its weakest. Plus, lower levels of the atmosphere are dripping with moist air.
August, September and October have accounted for more than 80 percent of the 600-plus hurricanes recorded since 1866. June and July account for only about 9 percent.
Those three months in the heart of the season account for about 95 percent of all major hurricanes, those with top sustained winds of at least 111 mph. And the six weeks starting in mid-August are when more than half of all hurricanes have happened.
But late-season storms also can do damage.
“As we get to the end of the season, the Atlantic’s cooling off, (and) the most favored areas of development shift back to the western Caribbean and specifically the eastern Gulf,” the hurricane center’s Feltgen said. “The western Gulf’s starting to shift already; you’re starting to get increased wind shear.”
Early and late season tropical cyclones have caused historic damage and death in Florida and elsewhere. Most were Gulf of Mexico storms. Highlights:
- Hurricane Wilma, Oct. 18-25, 2005. Came off Yucatan, moved ashore near Naples, and swung around and up the southeast Florida coast. Damage estimates topped $16 billion in South Florida alone. At least six Floridians killed. Left some 6 million households without power, many for weeks.
- Hurricane Mitch, Oct. 22-Nov. 9, 1998. Came up from near South American coast, grew into a Category 5, then weakened to a 2 before marking a rare landfall in Honduras. Drifted across Central America, where rain-driven floods and mudslides killed at least 9,000 people. Deadliest hurricane since 1780. Moved into gulf, coming ashore in southwest Florida as a tropical storm, it spawned five tornadoes, including one in Palm Beach County. Two died in the Keys.
- Tropical Storm Gordon, Nov. 8-21, 1994. Moved from Yucatan to Cuba, doubled back to eastern Gulf of Mexico, crossed Key West, then made landfall the next day at Fort Myers. Went out to sea, then came back and crossed Cape Canaveral as a tropical depression. Spawned six tornadoes. Killed 11. Dumped up to 16 inches of rain on South Florida in nine days. Caused $300 million in agricultural damage in Florida. Was hurricane strength in the Caribbean, where more than 2,000 died.
- Hurricane Alberto, June 2-6, 1982. It was born just off the Yucatan and grew from depression to hurricane in 18 hours, then hit wind-shear in the Gulf of Mexico and fizzled just hours before it would have moved across South Florida.
- Hurricane Abby, June 1-13, 1968. It came up through the Gulf of Mexico and lost hurricane strength before making landfall near Punta Gorda; brought heavy rains to peninsular Florida, helping end a drought.
“The bottom line is that this storm (Andrea) and Isaac stressed the fact that we shouldn’t be focusing on these skinny lines,” Palm Beach County Emergency Manager Bill Johnson said Friday. “We shouldn’t even be focusing on the track. This is another storm that wasn’t anywhere close to us. But we received a significant brunt of it. We just can’t write these storms off.”