Flooding is the number one natural disaster in the United States (FEMA Mitigation Directorate), causing more property destruction and financial loss than any other extreme weather event. While these hazards are talked about heavily during the summer months, flooding can cause dangerous impacts throughout the year. This is especially true in areas already prone to flooding such as along rivers or lake shores, and those that routinely deal with significant winter weather. For example, substantial melting of snow and ice in early spring can cause devastating results. Similar outcomes occur when rivers and streams are obstructed by large chunks of melting ice, a phenomenon popularly known as an ice jam. Many meteorological and hydrological processes can result in winter time flooding and it is important to be both aware of and prepared for these circumstances.
One way winter weather can contribute to flooding conditions is simply through the rapid melting of heavy snowpacks. Despite melting on the surface, early spring ground temperatures are often still below freezing. In this instance, water is not actively absorbed by the ground beneath and instead flows along the surface toward nearby rivers and lakes, raising water levels and increasing the chance for significant flooding. Flooding is also common as ice from frozen waterways begins to melt, break apart and flow downstream. If these often large pieces of ice approach either a natural or man-made obstruction (such as a river dam), the rivers flow can be impeded. This ice jam essentially blocks the natural movement of a river or stream and causes significant flooding. When the ice jam finally releases, built up water that was blocked from its usual flow rushes downstream and consequently contributes to serious flooding impacts.
Currently, not much can be done to prevent ice jams from occurring. However, it is essential for anyone living in areas prone to winter flooding to be aware of the danger and what can be done to minimize potential damage. In addition to purchasing flood insurance, the Federal Emergency Management Agency (FEMA) suggests making a flood evacuation plan and keeping important papers in a safe, waterproof place. Taking these precautionary steps can help reduce loss and destruction even during the most obscure or improbable of flooding scenarios.
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©2019 Weather Forecaster Dennis Weaver