Ice dams form when snow and freezing temperatures come in contact with heat escaping from a roof structure. The right conditions need to be present for an ice dam to form. There must be snow, there must be warm portions in the upper part of the roof, and there must be cold portions on the lower part of the roof.
When heat melts the snow, it travels down to the coldest region of the roof; the roof edge. Here snow melt water re-freezes as it begins to drip off the roof edge. It does not take long for a little frozen bump on a roof edge to grow into a large ice dam.
Naturally, some regions of the country are more vulnerable to ice dams than others. Which areas get the worst ice dams? You need only look at the cities throughout the country with the largest snowfall.
The Northeast is well-known for its icy winter weather, and cities in this region often top the list for average yearly snow. The higher the snowfall totals, the greater the chances of ice dams forming.
Some of the snowiest cities in the Northeast include:
The upper Midwest also gets some serious snowfall each year, and this region is also prone to damaging ice dams. Cities with the highest yearly snowfall totals include:
The West isn’t immune to snowstorms, and some areas receive high snowfall counts each year. The snowiest places in this region include:
Of all the cities in the country, Valdez, Alaska takes the crown as the snowiest. Each year, the city gets about 326.3 inches of snow on average. Alaska, as a whole, gets a generous amount of snow each year, but nothing beats the totals seen in Valdez. Naturally, this city and other nearby cities are highly vulnerable to ice dams.
The truth is that any region that gets any accumulation of snow is vulnerable to ice dams. But these cities see the ice dams on a more frequent basis because of their extremely predictable high snowfall totals each year.