Hurricane season living up to experts’ forecast

Author:
Publish date:
Updated on

They called for a very active season and at one point were tracking Gustav, Hanna, Ike and Josephine at the same time

They called for a very active season and at one point were tracking Gustav, Hanna, Ike and Josephine at the same time

Two days after Hurricane Ike stormed ashore with 110-mph winds at GalvestonIsland, search teams still were combing through wreckage along the Texas coast, searching for survivors who wouldn’t evacuate.

Though Ike, a 700-mile-wide behemoth, smashed Galveston and caused widespread damage in Houston — the nation’s fourth-largest city — when it made landfall Sept. 13, the 24-foot surge forecasters feared would blow ashore with the huge storm never materialized. An 11-foot wall of water left plenty of destruction, but it fell short ofthe “catastrophic” damage many had expected. The surge pushed as far as Louisiana, where rising waters flooded 26,000 homes in Terrebonne Parish.

At last report, 28 had died in Ike, many of those inland where rains caused heavy flooding. Search teams that went door-to-door in Galveston and elsewhere looking for survivors of rising Gulf waters had rescued nearly 2,000 people.

Two million residents evacuated the Texas and Louisiana coasts. Authorities were telling residents not to return to Galveston. They didn’t expect electrical power and other utilities to be restored there for at least a month.

Ike was the last in a conga line of hurricanes and tropical storms that danced across the Atlantic over several weeks at summer’s end, wreaking havoc in some places, causing great worry in others, and surprising many with their sheer number and intensity. But not the eminent hurricane prognosticator William Gray.

“Our forecasts were for a very active year,” says the ColoradoStateUniversity professor of atmospheric science. August proved the forecaster right. And with the approach of Sept. 10, the statistical height of the hurricane season, “conditions look better and better” for a lot more storms to form before the season ends Nov. 30, Gray says.

Gray was calling for four more named storms in September after Josephine, four of them hurricanes, two of them major ones (Category 3 or better). His Sept. 1 updated forecast for the 2008 season: 17 named storms, nine of them hurricanes, five major.

Why all this craziness? Why five named storms — Faye, Gustav, Hanna, Ike and Josephine — in a little less than three weeks (Aug. 15 to Sept. 3)? Why two Category 4s — Gustav and Ike — during that same period? And why four named storms — Gustav, Hanna, Ike and Josephine — marching across the Atlantic, swirling through the Caribbean and blowing over Louisiana at the same time?

Pretty crazy, but not surprising, the meteorologists say. Conditions were right for it. And if conditions are right, usually they are right at the height of hurricane season — that is, from mid-August to late October.

This isn’t the first time forecasters have had to track four named Atlantic storms at the same time, says Dennis Feltgren, a meteorologist at the NationalHurricaneCenter in Miami. In August/September 1995, they tracked five storms simultaneously — Felix, Humberto, Iris, Jerry and Luis. In September 1971, Edith, Fern, Ginger, Heidi and Irene swirled around the Atlantic region at the same time.

“We’re seeing all of the right ingredients for this tropical weather that we’ve been seeing this month,” says Feltgren.

First, warm water fuels hurricanes, says Feltgren. The band of tropical Atlantic waters between Puerto Rico and Africa’s west coast ranged from 82.5 to 86 degrees in August, according to NOAA’s ClimatePredictionCenter. Hurricane activity increases 49 percent during August and September with each 1-degree increase in average temperature in these tropical Atlantic waters, according to London researcher Mark Saunders.

Vertical wind shear — different wind speeds at different levels of the atmosphere, which interfere with hurricane formation — has been about average for the time of year, which is pretty weak, Gray says. Air pressure at the sea surface has been low — the lowest since 1948. Low sea-surface pressures lead to instability in the air and weaker trade winds, according to Gray.

Humidity has been high, which promotes hurricane formation, and the waves of unstable air rolling off Africa in the tropical latitudes have been strong, says Gregory Jenkins, an atmospheric scientist and expert in West African climate with Howard University in Washington, D.C. These waves roll off the West African bulge every three to five days. In August, they were “fairly strong” and pushing off the African coast every three days.

Jenkins identifies another ingredient in the August-September flurry of named storms: the dearth of Saharan dust in the atmosphere in the tropical belt between Africa and the Caribbean. “August was very different this year,” he says. “There was really no dust at all. Normally, we have a lot of dust coming off the Sahara in June, July and August. It begins to slow down in September.”

He says dust absorbs sunlight, so the water becomes a little cooler; it brings with it drier air; and it promotes midlevel sheer, all of which inhibit hurricane formation, Jenkins says. He attributes the paucity of dust to an especially strong west African monsoon, which reached up into the Sahara from the southwest this year, causing heavy rainfall. A lot of Saharan dust in the air was one factor believed to have contributed to a mild 2006 hurricane season, Jenkins says.

Coastal residents up and down the Eastern Seaboard, in Florida and along the Gulf of Mexico were on pins and needles for three weeks trying to figure out where Faye, Gustav, Hanna, Ike and Josephine would ultimately go. Up the East Coast? Over Florida? Into the Gulf of Mexico? How far west into the Gulf?

Usually the Bermuda High is the key player in influencing the movement of storms churning west across the Atlantic, says Steve Letro, chief meteorologist at the National Weather Service office in Jacksonville, Fla. Depending on its location, it could send the storms harmlessly up the central Atlantic, to the East Coast or into Florida. But with these storms, there was a second series of highs over the southeastern United States. One of those highs blocked Faye, causing it to stall over Florida and dump up to 25 inches of rain in some places. Other highs pushing south and west over the southeast pushed Gustav and Ike west around Florida and into the Gulf of Mexico, where they hit the GulfCoast — Gustav in south-central Louisiana, Ike around Galveston.

As Ike set its sights on Texas Sept. 12 with 100-plus-mph winds, more than 1 million residents had evacuated around Galveston and Houston, and a huge swath of coast was battening down in anticipation of hurricane-strength winds along a 230-mile stretch and tropical storm winds across 530 miles of coastline. The National Weather Service warned that residents of one- and two-story homes would face “certain death” in the surge if they chose to stay on low-lying GalvestonIsland.

Gustav, a strong 115-mph Category 2 when it came ashore Sept. 1, struck at the heart of Louisiana’s sportfishing country, Terrebonne Parish, a marshy area laced with estuaries that supports some 65 charter boats, 7,500 “camps” — private waterfront cottages used mainly for staging fishing trips — and a number of small motel/marinas. “We’re pretty beat up,” says Capt. Stu Scheer, 63, who runs an inshore charter fishing business out of Cocodrie, where Gustav came ashore. “All the fishing operations are knocked out.”

Five to 6 feet of water flooded the end of Highway 56, the road where a lot of the marinas and charter boats are congregated, but farther up the road the water was just 3 feet. He says most of the charter boats either were hauled or found safe haven inland in the bayous. But the big winds damaged docks and piers, ripped roofs off bait houses and motels, and left most of Terrebonne without water or electricity. He expected the boats to be running again by October, but as Ike set its sights on Texas, high water was starting to flood Highway 56 again.

“We’re just keeping our fingers crossed,” says Scheer.

While Texas reeled from Ike, the Caribbean mourned heavy losses from repeated hits. Faye killed 23 in the Caribbean, 14 on Hispaniola alone. Gustav left another 84 dead on Hispaniola, 11 in Jamaica, and made landfall twice in Cuba, damaging or destroying 90,000 homes in Pinar del Rio and toppling 80 high-tension electrical towers. Torrential Hanna, though its winds never exceed 80 mph, left at least 529 dead in Haiti from flooding and mudslides. Ike caused more misery, damaging 80 percent of the homes in the Turks and Caicos, killing another 61 in Haiti, and giving Cuba a second thrashing, forcing the evacuation of 1.2 million people and damaging another 140,000 buildings.

Ike’s eye roared over Great Inagua in the southeastern Bahamas, causing worry about the 60,000 flamingos that reside in InaguaNational Park. But farther north at CoralHarbour on New Providence, Nick Wardel, who runs the Seven Seas Cruising Association station, says the northern Bahamas remained out of harm’s way. “It’s blustery today from the east to northeast,” says Wardel, who spoke to Soundings as Ike passed to the south and west in early September. “We’re fine. Just a lot of rain.”