Karen Clark & Company has released the KCC US Winter Storm Model Version 3.0, after company scientists and engineers analysed and incorporated the latest scientific information to further refine the advanced physical model.

“The winter storm peril, while not a solvency threat for major insurers, can produce large losses, as was demonstrated in February of 2021,” said Karen Clark, KCC cofounder and chief executive.

“A $30 billion winter storm event would not be a surprise today,” she said.

Version 3.0 introduces a refined method for calculating the effects of terrain on winter storms. In addition, new secondary building characteristics have been introduced for each sub-peril to capture the unique impacts of wind, snow/ice, and freezing temperatures on different building features and mitigation measures.

The company said: “While the annual expected losses from winter storms have not increased significantly, the probabilities of $20 billion and larger losses have increased.

“The KCC Winter Storm Model captures the two types of winter storms: extratropical cyclones and arctic air outbreaks.

“North American ETCs are large low-pressure systems, such as Nor’easters, that cause damage mainly due to strong winds and snow and ice accumulation.

“Arctic air outbreaks, often associated with high-pressure systems, are periods in which extremely cold polar air plunges south into the mid-latitudes, which can cause extensive damage due to long durations of subfreezing temperatures.

“The most recent notable example is the February 2021 event that caused nearly $20 billion in insured losses, as forecast by the KCC model.”

KCC said there was no current scientific consensus on how climate change was impacting the frequency or severity of winter storms in the US.

However, there is evidence that the severity of Arctic air outbreaks may increase as temperatures warm, due to a phenomenon called Arctic amplification. Scientists have observed that the Arctic is warming at a faster rate than the global average.

A warmer Arctic decreases the difference between the cold arctic air and the warm air in the mid-latitude regions, weakening the polar vortex.

When the polar vortex is weak, freezing arctic temperatures are more likely to dip down into the mid-latitudes, increasing the likelihood of anomalously cold temperatures in areas not generally prepared for these conditions.