Hurricane Earl a Harbinger of Worse to Come?

Hurricane Earl—now a Category 3 hurricane with winds of up to 115 miles (185 kilometers) an hour—is expected to nearly miss North Carolina's Outer Banks (map) early Friday morning.

But the storm could be the first of several intense hurricanes to menace the U.S. East Coast as the 2010 Atlantic hurricane season heats up, according to Jeff Masters, meteorological director for the Weather Underground website.

Hurricane Earl's path is expected to pass about a hundred miles (160 kilometers) offshore from Cape Hatteras around 2 a.m. ET Friday.

As of 11 a.m. ET Thursday, a hurricane warning had been issued for most of the North Carolina coast, as well as for much of Cape Cod, Massachusetts (see map), which Earl could brush late Friday night.

A hurricane warning means that meteorologists predict winds between 74 miles (119 kilometers) and 95 miles (153 kilometers) an hour.

The storm is headed for a likely landfall in Canada's Maritime Provinces (see map) Saturday morning as a Category 1 hurricane, with winds of up to 95 miles (153 kilometers) an hour.

Hurricane Earl's Path Holds no Direct Hits

Though downgraded, Hurricane Earl is expected to retain some of its power as it moves north.

Hurricanes gather strength from warm water, and this summer's Atlantic waters have been abnormally warm, Masters said.

Ocean temperatures along the U.S. East Coast north of Virginia usually aren't warm enough to support intense hurricanes.

(See "'Ominous' Pre-Katrina Conditions Now in Atlantic.")

Although Hurricane Earl's track could spawn tornadoes and cause flooding as it moves up the coast, two factors will reduce the hurricane's impact, Masters said.

A hurricane's rotation is counter-clockwise, which means that the hurricane's most powerful winds will be on the storm's right side, well away from land.

Hurricane Earl will increase its speed as it passes North Carolina, meaning less rainfall will accumulate on the left, or weaker, side of the storm.

Hurricane Earl: Just the Beginning?

Despite Hurricane Earl's near-miss, this year's fifth named storm may be a harbinger of the remainder of the hurricane season, which ends November 30, Masters said.

(Also see "Dramatic Increase in Hurricanes Likely Coming This Month.")

A series of storms could turn toward the U.S. East Coast during the next two weeks, he said.

First in line could be tropical depression Gaston, which was about 1,800 miles (2,900 kilometers) east of San Juan, Puerto Rico (see map) late Thursday morning.

Gaston is likely to intensify into a hurricane with winds of around a hundred miles (160 kilometers) an hour as it nears the eastern edge of the Caribbean Sea early next week.

From there, Gaston could turn northward, continue intensifying, and move toward the U.S. East Coast late next week, Masters said.

Tropical Waves Spawning Hurricanes

Hurricanes often form in September from thunderstorms that move off the western coast of Africa.

These storms, known as tropical waves, have spawned some of the worst hurricanes in history.

Masters noted that these stormy hurricane "seeds" are rolling into the Atlantic now.

"Don't even look off the coast of Africa," Masters said. "There's an impressive-looking tropical wave that came off yesterday, and it's showing signs of intensifying."

If that wave gathers steam, it will become tropical storm Hermine.