Extratropical cyclones (ETCs) are significantly more complex than tropical cyclone systems. Their primary energy source is not the warmth of ocean waters as in the case of tropical cyclones, but rather the contrast in temperatures between the poles and the equator. ETCs exist in a dynamic set of atmospheric conditions and typically comprise several meteorological features that constantly interact with one another. Because they tend to be most frequent during winter months, ETCs are often referred to simply as winter storms or, in extreme cases where frozen precipitation is involved, blizzards.
Dr. Robert Fovell, Professor of Atmospheric and Oceanic Sciences at the University of California, Los Angeles, and a globally recognized expert in numerical modeling techniques, undertook a year-long peer review of AIR's approach to modeling extratropical cyclone hazard. According to Dr. Fovell, AIR "…combines NWP and stochastic techniques in a new way...a unique approach that results in a highly realistic view of the risk from extratropical cyclones."
Winterstorms in Europe: Numerical Weather Prediction
Because a purely statistical approach is insufficient to capture the meteorological complexity of extratropical cyclones, AIR pioneered the use of physical modeling in the insurance industry’s first probabilistic catastrophe model to use numerical weather predication (NWP)— the AIR Extratropical Cyclone for Europe.
NWP is an advanced technology used by all major meteorological agencies around the world. It allows the complex three-dimensional structure of the damaging winds associated with these storms to be accurately represented in time and space—including the fine-scale features that contribute to the strongest surface winds.
Expanding on Innovation: Winter Storms in the U.S.
Based on the success of the European ETC model, AIR expanded its capabilities in numerical modeling to the United States. The AIR Winter Storm Model for the United States—the first U.S. model to use NWP technology— simulates separate and distinct footprints for damaging winds, precipitation, and freeze. Because wind, precipitation and temperature damage property differently, AIR's winter storm model features damage functions that capture the specific mechanisms by which each of these storm components inflicts damage.
AIR currently offers extratropical cyclone models for:
United States (contiguous)
- Czech Republic
- United Kingdom*
* Includes coastal storm surge flooding
Listed below are additional materials of interest to companies exposed to extratropical cyclone, or winter storm, risk: