Winter Storms Have Grown More Devastating

Severe winter storms that leave behind millions of dollars in damage have become less common in the United States over the last five decades. But at the same time, individual storms have become more massive and destructive.

Climatologists suspect that these changes in winter weather are a consequence of global warming.

Between 1949 and 2003, the continental US faced 202 catastrophic winter storms, each causing over one million dollars in damage. They dumped freezing rain and snow, usually propelled by strong winds, and in some cases were followed by rapid thawing that led to floods.

The northeastern states were frequently hit by devastating weather. New York had the most storms of any state, at 83, followed by Pennsylvania with 77. Idaho and Arizona got off relatively lightly compared to the rest of the nation, with three severe storms apiece.

The winter storm track, however, has gradually moved farther south. States in the south-central US now see storms more often in winter, particularly Texas where they have doubled in number since the 1960s and 1970s. Overall though, large blizzards have become less common, dropping from an average for the country of 39 per decade to 30.

While there are fewer storms, recent ones cover greater area. During the 1950s and early 1960s, a winter storm would travel through an average of five or six states. By the late 1990s, that figure had nearly doubled to ten states per storm.

Altogether the 202 major blizzards left damage costing $35.2 billion in 2003 US dollars. A single snowstorm that swept through most of the eastern states from March 11 to 14 in 1993 accounted for $1.8 billion of the expense. The eastern half of the continental US received the brunt of losses, amounting to 88% of insurance claims between 1949 to 2003.

Blizzards in recent years have been exceptionally severe and costly. A fiscal calibration of the damage from each storm, used to measure a storm's intensity, reveals a huge rise in a typical storm's fury. During the late 1970s, storm cleanup averaged $8.4 million per state. That has climbed to $40 million per state in recent years.

Storms are particularly bigger and more damaging across the southern two-thirds of the country. Average recovery costs per storm in the south have nearly tripled since 1964.