Peter Dailey is vice president and director of atmospheric science at catastrophe modeler AIR Worldwide.

What is the forecast for the 2013 hurricane season?

AIR catastrophe models are not meant to forecast the frequency or severity of hurricanes in any particular season. Rather, they are intended to help insurance companies understand and manage their potential losses over a range of potential future seasons. That said, AIR does monitor seasonal predictions made by others and the broad consensus is for an above average number of named storms and an elevated number of those storms becoming hurricanes. These forecasts, in general, are in line with the forecast recently published by NOAA, which predicts 12 to 18 named storms (with maximum winds of at least 39 mph), of which 6 to 10 are predicted to become hurricanes (with winds of at least 74 mph).

It is important to note, however, that a high level of hurricane activity does not necessarily correlate to an elevated potential for landfall or insured loss. High levels of loss are typically the result of strong hurricanes making landfall, which itself is dependent on a host of correlated factors including sea surface temperatures, wind shear conditions, and atmospheric steering currents.

Are the paths of storms expected to be different this year, following events such as Irene and Sandy? Will the storms be more violent?

No, there is no clear evidence that the paths of Atlantic storms will be statistically different than the long term average. Sandy and Irene were both products of a unique set of circumstances, and ultimately the track of each tropical cyclone is unique and challenging to forecast even days in advance. No technology exists today which can forecast individual storm tracks a season in advance. There is some evidence that warmer than average Atlantic Ocean temperatures can lead to more storms developing far from the U.S. and curving out to sea sooner, but this is an active area of research and no definitive conclusions have been reached.

While there are studies that suggest that elevated ocean temperatures (owing to climate change) may lead to less frequent but more intense hurricanes in the Atlantic, there is little evidence that storms occurring in any one season will be more or less violent than average due explicitly to the effects of climate change. Sea surface temperatures in the Atlantic and Pacific oceans are important to defining hurricane risk in North America. Atlantic Ocean temperatures are expected to remain warmer than average, as they have been since 1995, which would suggest an impetus for elevated activity. Pacific Ocean temperatures are expected to be close to average this year, suggesting that the ENSO cycle (El Nino / La Nina) will not play a very large role in the Atlantic.

Is hurricane forecasting cyclical? Are there 'seasons' that play out across many years?

Each hurricane season is unique and the hurricane forecasts published each season by various agencies are dependent upon a host of factors including predicted Atlantic sea surface temperatures and El Nino conditions. However, some aspects of the climate that influence the forecast move in cyclical patterns. The El Nino Southern Oscillation (ENSO, i.e., El Nino / La Nina) in the Pacific recurs over a period of 3 to 8 years and can significantly modulate Atlantic Ocean activity owing to its effects on vertical wind shear in the atmosphere. Other climate factors vary on different time scales, such as the Quasi-Biennial Oscillation, which has a two year repeat cycle. So, in some sense, the climatological factors that influence Atlantic hurricane activity do evolve over the course of several years, but since each factor has its evolution, it would be difficult to relate activity levels to any one "cycle".

Special Reports /

On Eve of Hurricane Season, a Q&A with AIR's Peter Dailey

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