Title: River Ice Jam Potential

Purpose: There are two main types of ice jams ... freeze-up and break-up. Freeze-up ice jams occur during the early winter months whereas break-up ice jams occur during the late winter months as Spring emerges. Break-up ice jams pose a significant threat, as large chunks of ice tend to aggregate and cause flooding and damages to infrastructure. If any potential of warming patterns and precipitation which could accelerate ice thaw and cause the ice to break-up, this tool will aid forecasters with assessing the possibility of an ice jam.

Comments: Freezing Degree Days (FDD) are simply the freezing temperature (32°F) minus the daily mean temperature. It is simply a measure of how cold it has been and how long it has been cold. A greater number indicates that temperatures have been well below freezing over time. In calculating FDD, any missing daily data from the sites shown on the map are replaced with the average FDD for that particular missing day.

Potential Max Ice Thickness is the square root of AFDD in where the maximum temperature was ≤ 32°F. It is simply meant to be an estimate and not actual ground truth.