National Weather Service United States Department of Commerce

The winter season brings a variety of adverse weather extremes. You may experience heavy snow, ice accumulation, freezing temperatures and wind chill. Winter storms are often called the "deceptive killers" since many deaths can be attributed to indirect causes of adverse weather. For example, icy roads lead to an increase in traffic accidents.  Prolonged exposure to the cold may enhance chances for hypothermia, and stress from snow removal my increase changes for heart  related problems. It is important to recognize the different types of extreme weather that can be experienced during the winter season.

 

Cold Temperatures

Exposure to cold can cause frostbite or hypothermia and become life-threatening. Infants and elderly people are most susceptible. What constitutes extreme cold varies in different parts of the country. In the South, near freezing temperatures are considered extreme cold. Freezing temperatures can cause severe damage to citrus fruit crops and other vegetation. Pipes may freeze and burst in homes that are poorly insulated or without heat. In the North, extreme cold means temperatures well below zero.
 
With a snow cover, an arctic cold wave hit northeast Kentucky during January of 1994. Dawn on Wednesday January 19th had observed temperatures of 20 to 30 degrees below zero. Ashland had 25 below zero, while Grayson had 31 degrees below zero. It was one of the coldest mornings in recorded history for northeast Kentucky.
 
Wind Chill is the temperature it “feels like” outside and is based on the rate of heat loss from exposed skin caused by the effects of wind and cold. As the wind increases, the body is cooled at a faster rate causing the skin temperature to drop. Wind Chill does not impact inanimate objects like car radiators and exposed water pipes, because these objects cannot cool below the actual air temperature.
 
The NWS will inform you when Wind Chill conditions reach critical thresholds. A Wind Chill Warning is issued when wind chill temperatures are life threatening. A Wind Chill Advisory is issued when wind chill temperatures are potentially hazardous.
 
Exposure to low wind chill values may increase your chances of frostbite. Frostbite is an injury to the body caused by freezing body tissue. The most susceptible parts of the body are the extremities such as fingers, toes, ear lobes, or the tip of the nose. Symptoms include a loss of feeling in the extremity and a white or pale appearance. Medical attention is needed immediately for frostbite. The area should be SLOWLY re-warmed.
 
 
The NWS will inform you when Wind Chill conditions reach critical thresholds. A Wind Chill Warning is issued when wind chill temperatures are life threatening. A Wind Chill Advisory is issued when wind chill temperatures are potentially hazardous. Refer to the chart below so that you will be able to judge the dangers of wind chill.
 
Wind Chill Chart
 
 

 

Snow

Heavy snow can immobilize a region and paralyze a city, stranding commuters, closing airports, stopping the flow of supplies, and disrupting emergency and medical services. Accumulations of snow can cause roofs to collapse and knock down trees and power lines. Homes and farms may be isolated for days and unprotected livestock may be lost. In the mountains, heavy snow can lead to avalanches. The cost of snow removal,repairing damages, and the loss of business can have severe economic impacts on cities and towns.
 
Northeast Kentucky was on the western edge of the heavy snow and strong winds from the storm of March 12 into the 14th in 1993. The media labeled this event the “the storm of the century". Snow accumulations of around 2 feet fell over Lawrence and Boyd Counties. For example, Ashland measured 24 inches on the 14th of March. Amounts dropped off toward a foot in portions of Greenup and Carter Counties. Grayson and Greenup both measured 14 inches on the ground. 
 

Ice Storms

Heavy accumulations of ice can bring down trees and topple utility poles and communication towers. Ice can disrupt communications and power for days while utility companies repair extensive damage. Even small accumulations of ice can be extremely dangerous to motorists and pedestrians. Bridges and overpasses are particularly dangerous because they freeze before other surfaces.
 

Ice storms are the result of prolonged periods of freezing rain. Freezing rain occurs if the warm layer in the atmosphere is deep and there is a shallow layer of below freezing air at the surface. The precipitation can begin as either rain and/or snow but becomes all rain in the warm layer. The rain falls back into the air that is below freezing but since the depth is shallow, the rain does not have time to freeze into sleet.

Upon hitting the ground or objects such as bridges and vehicles, the rain freezes on contact. Some of the most disastrous winter weather storms are due primarily to freezing rain.

 
 
 
 Image  courtesy of the NWS JetStream project
 
The ice storm of January 2009 caused considerable damage across the state of Kentucky. Snow moved up the Ohio River Valley and overspread northeast Kentucky during the predawn hours of Tuesday the 27th of January in 2009. By afternoon, the snow decreased and transitioned to intermittent light freezing rain. Temperatures were in the mid and upper 20s. The intensity of the freezing rain increased for the evening hours. Ice accretions of around a half inch were widespread across northeast Kentucky, with heavier amounts to the west. The intensity of the freezing rain decreased during the predawn hours of the 28th, while temperature crept up toward the freezing mark. The storm ended as a quick burst of snow, adding a coating of snow on top of the ice.
 
Numerous trees fell or sagged onto power lines. Evergreen trees were especially vulnerable. The trees were not only coated with ice, but the rain added weight to the snow that was already on the trees. Many roads were impassible due to downed trees and power lines. Homes sustained damage from fallen trees.
 
The storm caused Kentucky's largest power outage on record, with 609,000 homes and businesses without power across the state. Property damage was widespread, with the damage due to falling trees, large tree limbs and power lines weighed down by ice. In the Louisville metropolitan area, 205,000 lost power and it took up to 10 days to get everyone hooked back up. Area school systems were closed for an entire week. Several emergency shelters were set up across the affected region. In Louisville's local school system, 69 schools lost power.
 
Check the Kentucky Winter Weather Portal to learn more about preparing for winter weather, and how the National Weather Service can help keep you ready to face extreme winter weather.