Here we go again. If you've spotted a new water stain in the ceiling since the snow and ice earlier this month, it probably was caused by ice damming.
Almost unheard of in these parts 10 years ago — actually, until the winter of 2006-07 — ice damming has become almost as common in late fall and winter in Oklahoma as deer season.
Transplanted Northerners might wonder what the hubbub is about. Ice damming is as common as snow shovels in northern climes. (Come to think of it, snow shovels, too, have popped up in stores around here with every snowstorm for several years now. Is Oklahoma drifting north?)
Ice damming is when ice builds up along the edges of roofs and backs up under shingles and flashing. When it melts, it damages roofs and causes leaks, usually along walls. On-and-off-again melting is the worst.
Around here, damming seems to take a combination of ice and snow, or sleet and snow. Blowing snow alone doesn't accumulate, or cause damming.
It looks like damming can occur even when the air temperature doesn't rise above freezing. The sun on a freezing but clear day causes enough melting, especially on a dark roof, to let water run — then freeze again and back up at nightfall, then melt again sometime after sunrise, and cause damage.