2015 Atlantic hurricane season predicted to be below average

Researchers at Colorado State University (CSU) expect an Atlantic hurricane season below average in 2015, with the CSU Tropical Meteorology Project team calling for eight named storms over the June 1 to Nov. 30 season.

Citing the development of a strong El Nino event and unfavourable hurricane formation conditions in the tropical Atlantic, CSU reported on its website Tuesday that these factors support an expectation the hurricane season for the Atlantic basin in 2015 will be well below average.

The team predicts that 2015 tropical cyclone activity will be about 40% of the average season, the website article notes. “By comparison, 2014’s tropical cyclone activity was about 75% of the average season.”

Of the named storms – three of which (Ana, Bill and Claudette) have already formed – two are expected to become hurricanes and one to reach major hurricane strength, with sustained winds of 111 miles/hour or greater.

Beyond the eight named storms, two hurricanes and one major hurricane, the forecast report indicates the total season includes 25 named storm days, eight hurricane days, and 0.5 major hurricane days.

Phil Klotzbach, lead author of the forecast report, advises coastal residents to be prepared despite the prediction of a below-average hurricane season. Inactive Atlantic hurricane seasons can still have major U.S. hurricane damage, CSU reports, citing Hurricane Andrew in 1992 as one example.

Related: U.S. researchers predict below-average 2015 Atlantic hurricane season

The report also includes post-July 31 predictions of the probability of major hurricanes making landfall on U.S. soil:

• 23% for the entire U.S. coastline (full-season average for the last century is 52%);

• 12% for the U.S. East Coast, including the Florida peninsula (full-season average for the last century is 31%);

• 12% for the Gulf Coast from the Florida panhandle westward to Brownsville (full-season average for the last century is 30%); and

• 12% for the Caribbean (full-season average for the last century is 42%).

A chart in the forecast report lists the post-July 31 hurricane impact probabilities for 2015, with Florida at the top of the list for hurricane with 22%, Texas at 13%, Louisiana at 12% and North Carolina at 11%. For major hurricane, the top states are Florida at 8%, followed by Texas and Louisiana at 4% each, and North Carolina at 3%.

“We expect the remainder of the Atlantic basin hurricane season to accrue Net Tropical Cyclone (NTC) activity approximately 35% of the seasonal average,” the report abstract notes.

The CSU forecasts are based on more than 60 years of historical data, including Atlantic sea surface temperatures, sea level pressures, vertical wind shear (the change in wind direction and speed with height in the atmosphere), El Nino (warming of waters in the central and eastern tropical Pacific), and other factors. The forecast is intended to provide a best estimate of activity to be experienced during the upcoming season, not an exact measure.