The 2009 Atlantic hurricane season should be "near-normal" but that can still mean deadly and costly, the federal government said Thursday.
Forecasters estimated a 70 percent chance of having nine to 14 named storms, of which four to seven could become hurricanes, including one to three major hurricanes — Category 3, 4 or 5.
The forecast also cited a 50 percent probability of a near-normal season, a 25 percent probability of an above-normal season and a 25 percent probability of a below-normal season.
The federal government said forecasts have become a bit more difficult given weather changes.
"Global weather patterns are imposing a greater uncertainty in the 2009 hurricane season outlook than in recent years," the National Oceanic and Atmospheric Administration said in a statement.
"Shaping this seasonal outlook is the possibility of competing climate factors," it added. "Supporting more activity this season are conditions associated with the ongoing high-activity era that began in 1995, which include enhanced rainfall over West Africa, warmer Atlantic waters and reduced wind shear. But activity could be reduced if El Nino develops in the equatorial Eastern Pacific this summer or if ocean temperatures in the eastern tropical Atlantic remain cooler than normal."
Forecasters give a tropical storm a name when wind speeds reach 39 mph and upgrade it to a hurricane when sustained winds reach 74 mph. Major hurricanes have winds of more than 111 mph. The same type of storm is known as a typhoon or tropical cyclone in other parts of the world.
Call to action
Gerry Bell, lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center, noted that "the outlook is not just about the numbers, it’s also about taking action. Prepare for each and every season regardless of the seasonal outlook.
"Even a near- or below-normal season can produce landfalling hurricanes," he added, "and it only takes one landfalling storm to make it a bad season."
Most Atlantic tropical storms form between June 1 and Nov. 30, though some have formed both before and after those dates.
The 2008 season was the 14th most active since 1950, with 16 named tropical storms, including eight hurricanes, of which five were considered major.
Half of the 2008 tropical storms impacted the U.S. coast, including four hurricanes. Three of those made landfall in the U.S.
The long-term average has been 11 tropical storms, of which 6 become hurricanes and 2-3 of those major hurricanes.
Still in 'high-activity era'
The National Hurricane Center has observed that since 1995 the Atlantic has been in a "high-activity era." Last year was the 10th above-normal season since 1995.
A record four major hurricanes hit the United States in 2005, including Katrina which killed around 1,500 people along the Gulf Coast and caused $80 billion in damage, making it the costliest natural disaster in U.S. history.
NOAA on Thursday also predicted a below-normal hurricane season around Hawaii and the Central Pacific Basin, and a normal or below-normal season in the Eastern Pacific.
The government forecast is the latest of several to predict a less active Atlantic hurricane season than in 2008, when hurricanes Gustav and Ike shut offshore oil and natural gas production platforms in the Gulf of Mexico and refineries in Louisiana and Texas. Hundreds of lives were also lost, mostly in the Caribbean.
Ike caused an estimated $19.3 billion in damages in the United States, making it the fourth costliest hurricane ever.
Last week, private forecaster AccuWeather.com also reduced its forecast, predicting 10 named storms, not 12 as it had forecast in March.
AccuWeather also forecast that:
- Six of the storms will be hurricanes, down from eight predicted in March, with two of them rated category 3 or stronger on the five-step Saffir-Simpson scale.
- Three tropical storms will hit the U.S. coastline, including two hurricanes, one of which could be at least category 3 strength. That forecast is unchanged from March.
"Anywhere along the U.S. coast is susceptible to an impact, but the Texas coast early in the season and East Coast from Carolinas northward during the heart of the season are areas that have us worried," said AccuWeather Hurricane Forecaster Joe Bastardi said in a statement.
A weak El Nino pattern of warm water in the Pacific Ocean is expected to create wind shear to blow apart storms while cool water in the tropical Atlantic ocean will rob the storms of their primary energy source as dust and dry air blowing from Africa will inhibit storm development, AccuWeather said.