Below Average Hurricane Season, Colorado State Forecasters Say
A well below-average hurricane season continues to be on tap for the Atlantic basin in 2015, Colorado State University Tropical Meteorology forecasters said in a Tuesday press release.
While hurricane season still has nearly four months until it ends Nov. 30, there are currently no brewing storms to worry about. And not much in the way of rain to end the territory’s months-long drought.
While David Sanchez, a meteorologist at the National Weather Service in San Juan said Tuesday that he expects showers to increase Wednesday morning through Friday, the amount of rainfall won’t help much.
“It’s not going to be enough to end the drought,” he said.
He said a tropical wave should pass south of St. Croix late Saturday into Sunday, which should bring a bit of rain to that island.
As for a wave now coming off the west coast of Africa, Sanchez said that three or four days ago, it appeared that it would develop into something stronger, but that forecast has changed.
“It will pass as an open wave” around the Aug. 14, he said.
Meanwhile, the Colorado State team indicated that the tropical Atlantic continues to exhibit conditions that are less conducive for tropical cyclone formation, and a strong El Niño event has already developed.
“Historical data indicate fewer storms form in these conditions,” lead author Phil Klotzbach said.
He said Caribbean vertical shear, which inhibits the development of hurricanes, was at record high levels through the end of July.
"So far, the 2015 season is exhibiting characteristics similar to the 1965, 1972, 1982, 1987 and 1997 hurricane seasons, all of which had below-normal activity," Klotzbach said.
The team is calling for eight named storms during the Atlantic hurricane season, which officially runs from June 1 to November 30. The eight named storms include Ana, Bill and Claudette, which have already formed. Of those eight named storms, researchers expect two to become hurricanes and one to reach major hurricane strength with sustained winds of 111 miles per hour or greater.
The long-term average stands at 12 names storms, 6.5 hurricanes and two major hurricanes.
The team bases its forecasts on over 60 years of historical data that include Atlantic sea surface temperatures; sea level pressures; vertical wind shear, which is the change in wind direction and speed with height in the atmosphere; El Niño, which is the warming of waters in the central and eastern tropical Pacific; and other factors.
The team predicts that 2015 tropical cyclone activity will be about 40 percent of the average season. By comparison, 2014’s tropical cyclone activity was about 75 percent of the average season.
The report also includes the probability of major hurricanes making landfall on U.S. soil and the Caribbean. They put it at 12 percent for the Caribbean.
The CSU team will issue two-week forecasts beginning Tuesday and continuing every other Tuesday through the remainder of the peak of the Atlantic hurricane season.
This is the 32nd year that CSU researchers have issued the Atlantic basin season hurricane forecast. William Gray launched the report in 1984.
The CSU forecast is intended to provide a best estimate of activity to be experienced during the upcoming season, not an exact measure.
Klotzbach cautioned coastal residents to take the proper precautions, regardless of the below-average basinwide forecast. Inactive Atlantic hurricane seasons can still have major U.S. hurricane damage, with three relatively recent notable examples being Hurricane Betsy in 1965, Hurricane Alicia in 1983 and Hurricane Andrew in 1992.
“It takes only one landfall event near you to make this an active season,” he said.