An overview of ice storms and their impact in the United States

Abstract

Ice storms, defined by the US National Weather Service as freezing rain accumulations over 0.635 cm (0.25 inch), are often costly and destructive. Formation processes include the classic 'melting' process and supercooled warm rain process. Freezing rain is most commonly found ahead of a warm front or occlusion, where warm air is lifted over a cold shallow layer near the surface. Other synoptic patterns conducive to freezing rain include arctic fronts, isentropic lift over an arctic air mass, and cold air damming. Causes of spatial and temporal variations in freezing rain include, but are not limited to, terrain and proximity to water. Areas with the most occurrences of freezing rain in the United States include the Pacific Northwest, Upper Midwest, and Northeast/Appalachian regions. Empirical forecasting methods and numerical weather prediction are currently used to predict freezing rain. Successful forecasting of ice storm events requires evaluation of the thermodynamic profile of the atmosphere. Local effects such as proximity to water and topography must be taken into account, and non-linear processes such as latent heating and cooling must not be ignored. Ice accumulation can cause tree damage, which, in addition to breakage of electrical cables, can lead to power outages. Deposition of ice also impacts road, rail, and air travel, with associated economic costs due to lost hours as workers are unable to travel. Ice storms also provide a significant risk to human health and life, with falling debris and slippery surfaces being primary threats.

A method to estimate freezing rain climatology from ERA-Interim reanalysis over Europe

“…For example, the ice coating formed on trees and power lines causes them to fail, leading to severe power outages, transportation disruption, delays in emergency responses and severe economic losses (Call, 2010;Lambert and Hansen, 2011). Lighter freezing rain events are also harmful because of their indirect effects, the most important being the reduced friction on road surfaces that results in increased rates of accidents, injuries, and difficulties in transportation (Degelia et al, 2015).…”

Short-Term Increase in Abundance of Foliage-Gleaning Insectivorous Birds Following Experimental Ice Storms in a Northern Hardwood Forest

“…Ice storms have heterogeneous effects on forested ecosystems as severity depends on stand age, species composition, elevation, proximity to water, slope, aspect, ground surface temperature, precipitation, and wind (Bruederle and Stearns, 1985;Seischab et al, 1993;Irland, 2000;Rhoads et al, 2002;Degelia et al, 2016). Damage wrought by icing ranges from loss of twigs and fine branches to the destruction of the entire crown of large trees (Rogers, 1923;Smith, 2000;Nielsen et al, 2003) with concomitant change to leaf area, canopy cover, and stand height (Rhoads et al, 2002;Weeks et al, 2009).…”

“…While ice storms occur relatively frequently, these storms are difficult to study due to their stochastic nature, large variability in intensity, and the spatially heterogenous nature of their effects over landscapes (Millward and Kraft, 2004;Wuebbles et al, 2014;Kayler et al, 2015;Degelia et al, 2016). The implementation of experimental ice storms of realistic intensity over a mature hardwood forest canopy in the White Mountains of New Hampshire, USA provided an uncommon opportunity to quantify interactions between insectivorous birds and their lepidopteran prey after glazing events of varying severities.…”

An Exceptional Case of Freezing Rain in Bucharest (Romania)

“…The extensive ice accumulation on the ground associated with freezing rain can lead to a significant impact on human activities, surface and air transportation, infrastructure and electrical power transmission [4][5][6][7]. Also, freezing rain events associated with a small accumulation of ice or those that occur over a short period can also result in transportation difficulties and an increase in the number of accidents [8].…”