In an ominous update, the government's lead hurricane forecaster warned Wednesday that the Atlantic tropical-storm season, now approaching its annual peak, could become "extremely active."

Bumping up the numbers from its earlier forecast, the Climate Prediction Center said it anticipated 14 to 19 named storms — those with winds of at least 39 mph, with two to five of those becoming major hurricanes, with winds of at least 111 mph — by season's end. The season ends on Nov. 30.

The long-term normal for the Atlantic Basin, which includes the Caribbean and the Gulf of Mexico, is 11 named storms, with two of those becoming major hurricanes.

In releasing the forecast, the center's Gerry Bell said the robust early-season activity – six named storms already have formed; two would be the normal for an Aug. 9 – is an indicator that the tropics are primed.

He cited five factors that favor an active season the rest of the way, including the lack of an El Niño in the tropical Pacific. During an El Niño, warm sea-surface temperatures interact with the atmosphere to generate shearing winds from the west that can snuff out Atlantic storms.

He also noted warmer-than-normal waters in the hurricane-spawning grounds of the Atlantic Basin, and computer-model guidance that suggested a busy season.

The update was the latest to add a dash of menace to the outlook for hurricanes, and splashed some cold water on recent speculation that an active-hurricane period that began in 1995 in the Atlantic Basin was about to yield to a quieter period.

Active and so-called lull periods have alternated in 25- to 40-year cycles, and Bell said that right now the long-term signals are mixed.

In deference to the limits of the science, the government does not get into predicting how many storms would make U.S. landfall.

Sandy notwithstanding (technically it wasn't a hurricane when it hit New Jersey), the nation has experienced a historic run of luck. Not a single major hurricane has hit the U.S. coasts since 2005.

Andrew preparing to buzz-saw through Florida in 1992.
NOAA
Andrew preparing to buzz-saw through Florida in 1992.

This month happens to mark the 25th anniversary of the last time a category 5 hurricane, one with tornadic peak winds of 157 mph or better, hit the United States.

That was Andrew, which devastated South Florida in August 1992, during one of those lull years.