An updated Atlantic hurricane season predication has been released this week by the National Oceanic & Atmospheric Administration’s (NOAA) Climate Prediction Center. The updated 2007 Atlantic Hurricane Season Outlook still maintains the expectations for an above-normal season, says the national weather agency.

As we enter the peak months (August through October) of the Atlantic hurricane season, NOAA scientists are predicting an 85 percent chance of an above-normal season, with the likelihood of 13 to 16 named storms, with seven to nine becoming hurricanes, of which three to five could become major hurricanes (Category 3 strength or higher on the Saffir-Simpson Hurricane Scale).

The development of key climate factors through early August has increased the confidence of an above-
normal season, and has also led the NOAA team to slightly tighten the ranges that had been given in their May outlook – due to development of La Niña-like conditions exerting influence. In May, NOAA predicted a range of 13-17 named storms, with seven to 10 becoming hurricanes, and three to five becoming major hurricanes.

The climate patterns responsible for the expected above-normal 2007 hurricane season continue to be the ongoing multi-decadal signal (the set of oceanic and atmospheric conditions that have spawned increased Atlantic hurricane activity since 1995), warmer-than-normal sea surface temperatures in key areas of the Atlantic Ocean and Caribbean Sea, and the El Niño/La Niña cycle, according to Gerry Bell, Ph.D., lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center based in Camp Springs, Md.

“Most of the atmospheric and oceanic conditions have developed as expected, and are consistent with those predicted in May,” said Bell. “The biggest wild card in the May outlook was whether or not La Niña would form, and if so, how strong it would be.

“Today’s El Niño/La Niña forecast from the Climate Prediction Center indicates a slightly greater than 50 percent probability that La Niña will form during the peak of the hurricane season. But more importantly, we are already observing wind patterns similar to those created by La Niña across the tropical Pacific Ocean and Caribbean Sea that
encourage tropical cyclone development. The conditions are ripe for an above-normal season.”

NOAA’s seasonal outlooks do not specify where and when tropical storms and hurricanes could strike. Nevertheless, during above-normal seasons many of the storms form over the tropical Atlantic Ocean. These systems generally track westward, towards the United States and the Caribbean Sea, thereby posing an increased threat to these regions.

So far this season, there have been three Atlantic named storms (Andrea, Barry and Chantal), which is slightly above average. On average, one to two storms develop in June and July. The Atlantic hurricane season runs from June 1 through November 30.

source:NOAA.