For the six-month hurricane season, which begins June 1, NOAA’s Atlantic Hurricane Season Outlook says there is a 70 percent likelihood of 13 to 20 named storms (winds of 39 mph or higher), of which 7 to 11 could become hurricanes (winds of 74 mph or higher), including 3 to 6 major hurricanes (Category 3, 4 or 5; winds of 111 mph or higher).

These ranges are well above the seasonal average of 12 named storms, 6 hurricanes and 3 major hurricanes.

“With the devastation of Sandy fresh in our minds, and another active season predicted, everyone at NOAA is committed to providing life-saving forecasts in the face of these storms and ensuring that Americans are prepared and ready ahead of time.” said Kathryn Sullivan, Ph.D., NOAA acting administrator. “As we saw first-hand with Sandy, it’s important to remember that tropical storm and hurricane impacts are not limited to the coastline. Strong winds, torrential rain, flooding, and tornadoes often threaten inland areas far from where the storm first makes landfall.”

Three climate factors that strongly control Atlantic hurricane activity are expected to come together to produce an active or extremely active 2013 hurricane season. These are:

• A continuation of the atmospheric climate pattern, which includes a strong west African monsoon, that is responsible for the ongoing era of high activity for Atlantic hurricanes that began in 1995;
• Warmer-than-average water temperatures in the tropical Atlantic Ocean and Caribbean Sea; and
• El Niño is not expected to develop and suppress hurricane formation.

“This year, oceanic and atmospheric conditions in the Atlantic basin are expected to produce more and stronger hurricanes,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster with NOAA’s Climate Prediction Center. “These conditions include weaker wind shear, warmer Atlantic waters and conducive winds patterns coming from Africa.”

NOAA’s seasonal hurricane outlook is not a hurricane landfall forecast; it does not predict how many storms will hit land or where a storm will strike. Forecasts for individual storms and their impacts will be provided throughout the season by NOAA’s National Hurricane Center.

New for this hurricane season are improvements to forecast models, data gathering, and the National Hurricane Center communication procedure for post-tropical cyclones. In July, NOAA plans to bring online a new supercomputer that will run an upgraded Hurricane Weather Research and Forecasting (HWRF) model that provides significantly enhanced depiction of storm structure and improved storm intensity forecast guidance.

Also this year, Doppler radar data will be transmitted in real time from NOAA’s Hurricane Hunter aircraft. This will help forecasters better analyze rapidly evolving storm conditions, and these data could further improve the HWRF model forecasts by 10 to 15 percent.

The National Weather Service has also made changes to allow for hurricane warnings to remain in effect, or to be newly issued, for storms like Sandy that have become post-tropical. This flexibility allows forecasters to provide a continuous flow of forecast and warning information for evolving or continuing threats.