There are competing hypotheses for what has been happening in the Atlantic for the past 20 years.

The U.S. coastline has a below-average chance of being struck by a major system, according to Colorado State Universitys forecast.

The Atlantic should have a near-average storm season, producing four to eight hurricanes before it ends in November, according to NOAA Administrator Kathryn Sullivan.

A storm that would be named Bonnie threatens holiday cookouts and celebrations along the U.S. coast from North Carolina to Georgia over the Memorial Day weekend.

When the Atlantic hurricane season starts next week, the most active area might just be off the U.S. East Coast.

Think of it as Mother Natures roller-coaster ride: the shift between the weather patterns known as El Nio and La Nia that, at their worst, can cause havoc worldwide.

With El Nio fading, this years Pacific storm season, which starts Sunday, probably wont be as explosive.

An El Nio in the Pacific disrupted weather patterns to bring northern Alberta a dry fall and very little snow throughout the winter.