A team of scientists at Colorado State University led by Dr. Phil Klotzbach released their April forecast for the upcoming Atlantic Hurricane Season. Their forecast calls for 7 named storms, 3 hurricanes, and 1 major (Category 3 or higher) hurricane. These numbers are well below the 30 year averages of 12, 6, and 3 respectively. The forecasts are based on nearly 30 years of statistical data as well as comparisons to previous hurricane seasons. The report mentions that current atmospheric and oceanic patterns are similar to that of 2014. The 2014 Atlantic Hurricane Season, which also saw below normal activity, had 8 named storms, 6 hurricanes, and 2 major hurricanes.
There are many potential factors that ultimately determine how many tropical cyclones form in a given hurricane season. These factors include wind shear, dry air, ocean temperatures, the phase of the El Nino Southern Oscillation, and the location of semi-permanent pressure systems like the Bermuda-Azores High. The April forecast calls for El Nino to persist into the hurricane season which has been linked to less active Atlantic hurricane seasons due to increased wind shear in the main development region. Like in 2014, seas surface temperatures are anomalously low from the Cape Verde Islands west to the Central Atlantic. However, they are warmer than normal in the Gulf of Mexico.
In addition to 2014, Klotzbach’s team identified four other previous seasons with similar atmospheric and oceanic patterns in the Atlantic which were 1957, 1987, 1991 and 1993. One of these years may jump out to long time New England residents because 1991 was the year when parts of the region were struck by Category 2 Hurricane Bob in August and severely impacted by an unnamed hurricane known now as “The Perfect Storm” in October. Hurricane Audrey also caused significant damage in June 1957 along parts of the Louisiana and Texas coastlines. It goes without saying that it is critical residents along vulnerable coastlines prepare for a potential hurricane every year regardless of the pre-season forecasts.
While the potential exists for a below normal hurricane season, this does not mean that it cannot be a destructive or notable season. In 2014 we had Hurricane Arthur make landfall along the Outer Banks of North Carolina in July, disrupting Fourth of July festivities as far north as New England. A Category 2 hurricane, Arthur was the strongest hurricane to make landfall in the United States since Hurricane Ike in 2008 and the earliest hurricane to strike North Carolina. Bermuda was also hit by two hurricanes (Fay and Gustav) a week apart later in the season. Even if there are fewer hurricanes predicted, it does not mean that the strongest hurricanes cannot form. Southern Florida was devastated by Category 5 Hurricane Andrew in 1992, a year with only six named storms.
Many people question the accuracy of pre-season hurricane forecasts as they are on occasion very different from what actually transpires. One of the reasons pre-season forecasts are useful is that they to provide guidance to local, state, and federal officials. If the forecast calls for an active season, governments can take extra steps to prepare should a hurricane head their way. Even though the forecast this time around calls for a below average number of tropical storms and hurricanes, scientists are unable to predict how strong the tropical cyclones that form will be or where they will go. It only takes one storm to make a hurricane season historic so everyone needs to be prepared.