Path of Hurricane Bill (2009)
An “active to extremely active” hurricane season is expected for the Atlantic Basin this year according to the seasonal outlook issued today by NOAA’s Climate Prediction Center, a division of the National Weather Service.
Across the entire Atlantic Basin for the six-month season, which begins June 1, NOAA is projecting a 70 percent probability of the following ranges:
- 14 to 23 Named Storms (top winds of 39 mph or higher), including:
- 8 to 14 Hurricanes (top winds of 74 mph or higher), of which:
- 3 to 7 could be Major Hurricanes (Category 3, 4 or 5; winds of at least 111 mph)
“If this outlook holds true, this season could be one of the more active on record,” said Jane Lubchenco, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. “The greater likelihood of storms brings an increased risk of a landfall.”
The outlook ranges exceed the seasonal average of 11 named storms, six hurricanes and two major hurricanes. Expected factors supporting this outlook are:
- Upper atmospheric winds conducive for storms. Wind shear, which can tear apart storms, will be weaker since El Niño in the eastern Pacific has dissipated. Strong wind shear helped suppress storm development during the 2009 hurricane season.
- Warm Atlantic Ocean water. Sea surface temperatures are expected to remain above average where storms often develop and move across the Atlantic. Record warm temperatures – up to four degrees Fahrenheit above average – are now present in this region.
- High activity era continues. Since 1995, the tropical multi-decadal signal has brought favorable ocean and atmospheric conditions in sync, leading to more active hurricane seasons. Eight of the last 15 seasons rank in the top 10 for the most named storms with 2005 in first place with 28 named storms.
“The main uncertainty in this outlook is how much above normal the season will be. Whether or not we approach the high end of the predicted ranges depends partly on whether or not La Niña develops this summer,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center.
“At present we are in a neutral state, but conditions are becoming increasingly favorable for La Niña to develop.”
NOAA scientists will continue to monitor evolving conditions in the tropics and will issue an updated hurricane outlook in early August, just prior to what is historically the peak period for hurricane activity.