The season runs from June 1 to Nov. 30. But the months of August, September and October have accounted for more than 8 in 10 of the 600-plus hurricanes recorded since 1866.
Those three months account for about 95 percent of all “major” hurricanes, those with top sustained winds of at least 111 mph.
And the six weeks starting around mid-August have generated more than half of all recorded hurricanes.
The misleading calm during the first two months of hurricane season is a period forecasters sometimes call the “preseason.” It averages only one hurricane every other year. Forecasters worry that will lull people in strike zones.
This is the first year since 2004 in which no storm developed somewhere in the Atlantic basin before the end of July. And the 2004 season had been only the third in 15 years.
But the tropics made up for lost time in 2004, generating 15 storms — the historical average is about 10 — with four slamming Florida between early August and late September.
That had never happened before in Florida, and not in any state since Texas in 1886.
Two of those, Frances and Jeanne, are well known to residents of Palm Beach County and the Treasure Coast.
The reasons we’re approaching the height of the season:
— Water in the Caribbean Sea and Atlantic Ocean, which provides the energy for storms, is at its warmest.
— Wind shear, the difference between high and low winds, which tends to “kneecap” storms, is at its weakest.
— Lower levels of the atmosphere are loaded with moist air.
— And conditions are best for the powerful tropical waves to form off the African coast and then have the warm water of the central Atlantic Ocean to fuel them as they move toward North America.
By late October, ocean temperatures are beginning to drop and cold fronts start pushing from the northern regions, increasing wind shear.
One encouraging sign for this year: El Niño has returned. Scientists say it tends to limit the formation of tropical storms and hurricanes in the Atlantic.
Limit, but not necessarily eliminate.
Relatively quiet seasons still can generate storms.
And as Tropical Storm Fay showed last year, inundating much of the Treasure Coast, a storm doesn’t need to be a monster to do a lot of damage.
Source Palm Beach Post 8/2/2009