NU Online News Service, May 30, 12:14 p.m. EDT
Despite the appearance of two pre-season tropical storms there is no change in the Atlantic hurricane forecast, which calls for an average year of storms, says one catastrophe modeler.
With the official start of the Atlantic Hurricane Season set to begin June 1, catastrophe modeler RMS released its pre-season commentary, saying conditions remain right for the total number of tropical storms “to be near the long-term average of 10.7 tropical storms.”
The season was kicked off early with Tropical Strom Alberto on May 19. RMS says Alberto is the earliest tropical storm to occur since Tropical Storm Ana on April 20, 2003.
The second named storm of the season, Tropical Strom Beryl, formed on May 27 and made landfall on Monday May 28.
According to the National Weather Service, Beryl, now a tropical depression, is centered off the coast of South Carolina moving east-northeast with sustained winds of 35 mph. The storm is expected to move along or just off the coast of North and South Carolina tonight before moving out into the Atlantic. The storm could strengthen over the next 48 hours and regain tropical-storm strength later today, the National Weather Service says.
RMS notes that while some existing conditions could drive higher Atlantic basin-activity, other factors, such as higher wind shear over the Atlantic, have increased “the likelihood of a near-normal season in 2012.”
RMS says sea-surface temperatures, which drive storms, are below average in the Atlantic main, but just above average in the Caribbean and Gulf of Mexico.
“The status of the El Niño-Southern Oscillation (ENSO) can also play a part in affecting the total number of storms during a season, with a higher number of tropical storms typically correlated with La Niña conditions and a lower number correlated with El Niño conditions,” says Neena Saith, director of catastrophe response at RMS. “There is a high amount of uncertainty associated with the seasonal forecasts, especially given the difficulty in predicting Atlantic sea-surface temperatures pre-season.”
The report cites the U.S. Climate Prediction Center as saying La Niña conditions dissipated in April, with “both oceanic and atmospheric patterns indicating a transition to ENSO-neutral conditions.”
RMS also notes that while the seasonal prediction calls for an average Hurricane season, it does not predict landfall rates or insured losses in the “Americas [that] remain highly dependent upon specific storm tracks and the behavior of individual storms.”