Winter Storms

Table of Contents
  1. Background
  2. Past Events & Location
  3. Extent
  4. Probability
  5. Impact & Vulnerability
  6. Hazard Vulnerability Summary Analysis

The National Weather Service defines a winter storm as a combination of heavy snow, blowing snow and/or dangerous wind chills. An ice storm as a storm which results in the accumulation of at least 0.25-inches of ice on exposed surfaces. Ice storms occur when cold air at the surface is overridden by warm, moist air. As the warm air advances and is lifted over the cold air, precipitation begins falling as rain, cools is it passes through the cold air mass below, and freezes upon contact with chilled surfaces at temperatures of 32°F or below.

Snowfall is precipitation that falls in the form of ice crystals and accumulates on contact with surfaces below 32°F. Snow is formed from moisture that freezes while still in the cloud, then falls through layers of below freezing temperatures.

Background

What is a Severe Winter Storm?

The NOAA National Severe Storms Laboratory defines a winter storm as an event in which the main types of precipitation are snow, sleet or freezing rain.

Why can winter storms be so dangerous?

Most deaths from winter storms are not directly related to the storm itself.

  • People die in traffic accidents on icy roads.
  • People die of heart attacks while shoveling snow.
  • People die of hypothermia from prolonged exposure to cold.

Everyone is potentially at risk during winter storms. The actual threat to you depends on your specific situation. Recent observations show that:

  • Of injuries related to ice and snow:
    • About 70% occur in automobiles.
    • About 25% are people caught out in the storm.
    • Majority are males over 40 years old.
  • Of injuries related to exposure to cold:
    • 50% are people over 60 years old.
    • Over 75% are males.
    • About 20% occur in the home.

Types of Winter Storm Alerts:

Winter Storm Warning: Issued when a combination of hazardous winter weather in the form of heavy snow, heavy freezing rain, or heavy sleet is imminent or occurring. Winter Storm Warnings are usually issued 12 to 24 hours before the event is expected to begin.

Winter Storm Watch: Issued 12-48 hours in advance of the onset of severe winter conditions. The watch may or may not be upgraded to a winter storm warning, depending on how the weather system moves or how it is developing.

Winter Storm Outlook: Issued prior to a Winter Storm Watch. The Outlook is given when forecasters believe winter storm conditions are possible and are usually issued 3 to 5 days in advance of a winter storm.

Winter Weather Advisories: Issued for accumulations of snow, freezing rain, freezing drizzle, and sleet which will cause significant inconveniences and, if caution is not exercised, could lead to life-threatening situations.

Frost/Freeze Warning: Below freezing temperatures are expected and may cause significant damage to plants, crops, or fruit trees. People who have homes without heat need to take added precautions.

Past Events & Location

Extent

Between 2000 and 2020, the BRADD Region received 4 FEMA disaster declarations for severe storms.

  • DR-1578-KY: Severe Winter Storm & Snow Record (2004)
  • DR-1818-KY: Severe Winter Storm (2009)
  • DR-4218-KY: Severe Winter Storm, Snowstorm, Flooding, Landslides, And Mudslides (2015)

The table below displays ice storm, winter storms, and heavy snow events that were reported to NOAA and NWS between 2000 and 2020. While not each of these events received a FEMA declaration, each showed clear characteristics of a severe winter storm.

Probability

Occurrence

Between 2000 and 2020 (21 years), the BRADD Region experienced 66 winter storm events. Please note that winter storm events, which share the same episode number from NCEI, are classified as the same event.

  • Allen County: 6 winter storm events/21 years = 0.29% chance of a winter storm events annually
  • Barren County: 9 winter storm events/21 years = 0.43% chance of a winter storm events annually
  • Butler County: 6 winter storm events/21 years = 0.29% chance of a winter storm events annually
  • Edmonson County: 8 winter storm events/21 years = 0.38% chance of a winter storm events annually
  • Hart County: 8 winter storm events/21 years= 0.38% chance of a winter storm event annually
  • Logan County: 6 winter storm events/21 years = 0.29% chance of a winter storm event annually
  • Metcalfe County: 6 winter storm events/21 years = 0.29% chance of a winter storm event annually
  • Monroe County: 5 winter storm events/21 years = 0.24% chance of a winter storm event annually
  • Simpson County: 6 winter storm events/21 years = 0.29% chance of a winter storm event annually
  • Warren County: 6 winter storm events/21 years = 0.29% chance of a winter storm event annually

Climate Change

Climate change has the potential to increase the severity of winter storms throughout the United States. Heavy snowfall and winter storms have increased in frequency in recent years. A 2012 study published in Geophysical Research Letters found that Arctic Amplification has increased snow and ice storms. As the Arctic warms and ice melts, the Arctic is less able to reflect sunlight thereby trapping heat and warming the atmosphere. This warming affects atmospheric circulation patterns that increases moisture in the air so that when temperatures drop and a storm front moves through, it is more likely to produce large amounts of snow. As the earth continues to gradually warm, this research indicates that communities should prepare to face harsher winters, more often.

Overall Probability

The BRADD Region experiences a moderate probability of future winter storms due to past events and as outlined using the classification definitions from FEMA. .

Impact & Vulnerability

Human-made structures such as buildings, light posts, and telephone poles are directly affected by winter storms. When heavy snow settles on the roofs of buildings it can cause a collapse due to extreme weight. Other structures can freeze and break due to accumulated from an ice storm. Essentially, almost any human-made object is indirectly vulnerable during an ice or snow storm. This is because broken and snapped objects such as tree branches and lights from light posts that break and fall during an ice or snow storm can cause damage to whatever is lying underneath them, i.e. cars.

Winter storms have the potential to impact the natural environment. Extended periods of snow covered grounds can alter habitats and the timing of certain species’ routines. Most all vegetation is absent from bloom during the times of winter storms, however ice storms can damage and even destroy trees, bushes, etc. If a winter storms occurs at an unexpected time of year it could ruin crop growth and natural vegetation.
The general population is vulnerable to any winter storm. Anyone exposed to the conditions of a storm will be impacted or will need to take steps to prevent an impact. Populations that are isolated will have difficulties obtaining adequate supplies. Winter storms give way to horrible road conditions, which can quarantine these populations for weeks at a time. Elderly populations or individuals with medical conditions may be adversely impacted by lack of electricity from downed power lines and inaccessible transportation networks.

Economy
Winter storms can have an economic impact on the community by forcing closure of businesses. Vehicular accidents and damage caused to buildings from snow loads may also increase insurance pay-outs.

It is predicted that due to climate change, there will be changes in snowfall across all of North America. The first seasonal snowfall may be delayed, there may be less overall snowfall, and there may be more events of rainfall/ice instead of snowfall. There are already declines in heavy snowfall in the southeastern United Sates due to rising temperatures. There is limited evidence correlating a decrease in ice storms to climate change; however, “Ning and Bradley project that the transition line between snow and rain will move 2º latitude northward by the end of the century. There is also limited evidence on hail projections. Some projects, however, show that there may be a longer hail season with larger hail, leading to more damage.”

The number of extreme cold events has been below average in recent winters in Kentucky. The freeze-free season is the amount of time between the last time it was 32º F in the spring and the first recorded 32º F in the fall. The season has lengthened across the United States and is 6 days longer in the Southeast region.

Potential impacts include:
  • Warmer winters
  • Decrease in cold precipitation (snow, hail, sleet)
  • Decrease in snowmelt events
  • Impacts to growing season and harvest
  • Economic impacts due to heating and infrastructure degradation

Hazard Vulnerability Summary Analysis

The BRADD Region experiences high vulnerability to winter storms due to past events, infrastructure impacts, and concern from local officials. For a look at vulnerability by county, click on the links below.

  • Between 2000 and 2020, NOAA and NWS reported 16 severe winter storms in Allen County.
  • On average, Allen County has experienced 6 winter storm events/21 years. This equates to a 0.29% chance of a winter storm event in Allen County annually.
  • In 2013, freezing rain from a winter storm caused a tree to fall on a house which resulted in $10,000 of property damage.

Because of these factors, Allen County experiences moderate vulnerability to winter storm events. Scottsville reflects Allen County’s overall history of winter storms, and therefore experiences moderate vulnerability as well.
  • Between 2000 and 2020, NOAA and NWS reported 20 severe winter storms in Barren County.
  • On average, Barren County has experienced 9 winter storm events/21 years. This equates to a 0.43% chance of a winter storm event in Barren County annually.
  • In 2010, icy road conditions resulting from a winter storm claimed the life of a Barren County driver.

    • Because of these factors, Barren County experiences moderate vulnerability to winter storm events. Cave City, Glasgow, and Park City reflect Barren County’s overall history of winter storms, and therefore experience moderate vulnerability as well.
  • Between 2000 and 2020, NOAA and NWS reported 19 severe winter storms in Butler County.
  • On average, Butler County has experienced 6 winter storm events/21 years. This equates to a 0.29% chance of a winter storm event in Butler County annually.
  • In 2018, 1,200 customers were left without power as a result of ice accumulation on powerlines.

Because of these factors, Butler County experiences moderate vulnerability to winter storm events. Morgantown, Rochester, and Woodbury all reflect Butler County’s overall history of winter storms, and therefore experience moderate vulnerability as well.
  • Between 2000 and 2020, NOAA and NWS reported 15 severe winter storms in Edmonson County.
  • On average, Edmonson County has experienced 8 winter storm events/21 years. This equates to a 0.38% chance of a winter storm event in Edmonson County annually.
  • In 2018, a number of trees fell as a result of ice accumulation.

Because of these factors, Edmonson County experiences moderate vulnerability to winter storm events. Brownsville reflects Edmonson County’s overall history of winter storms, and therefore experiences moderate vulnerability as well.
  • Between 2000 and 2020, NOAA and NWS reported 23 severe winter storms in Hart County.
  • On average, Hart County has experienced 8 winter storm events/21 years. This equates to a 0.38% chance of a winter storm event in Hart County annually.
  • In 2021, winter storm conditions led to a fatal crash on Interstate 65 in Hart County.

Because of these factors, Hart County experiences moderate vulnerability to winter storm events. Bonnieville, Horse Cave, and Munfordville reflect Hart County’s overall history of winter storms, and therefore experience moderate vulnerability as well.
  • Between 2000 and 2020, NOAA and NWS reported 16 severe winter storms in Logan County.
  • On average, Logan County has experienced 6 winter storm events/21 years. This equates to a 0.29% chance of a winter storm event in Logan County annually.
  • In February of 2015, 13 inches of snow accumulated across Logan County.

Because of these factors, Logan County experiences moderate vulnerability to winter storm events. Adairville, Auburn, Lewisburg, and Russellville reflect Logan County’s overall history of winter storms, and therefore experience moderate vulnerability as well.
  • Between 2000 and 2020, NOAA and NWS reported 16 severe winter storms in Metcalfe County.
  • On average, Metcalfe County has experienced 6 winter storm events/21 years. This equates to a 0.29% chance of a winter storm event in Metcalfe County annually.
  • In February of 2016, 10 to 14 inches of snow accumulated across Metcalfe County.

Because of these factors, Metcalfe County experiences moderate vulnerability to winter storm events. Edmonton reflects Metcalfe County’s overall history of winter storms, and therefore experiences moderate vulnerability as well.
  • Between 2000 and 2020, NOAA and NWS reported 14 severe winter storms in Monroe County.
  • On average, Monroe County has experienced 5 winter storm events/21 years. This equates to a 0.24% chance of a winter storm event in Monroe County annually.
  • In January of 2016, 8 to 10 inches of snow accumulated across Monroe County.

Because of these factors, Monroe County experiences moderate vulnerability to winter storm events. Fountain Run, Gamaliel, and Tompkinsville reflect Monroe County’s overall history of winter storms, and therefore experience moderate vulnerability as well.
  • Between 2000 and 2020, NOAA and NWS reported 16 severe winter storms in Simpson County.
  • On average, Simpson County has experienced 6 winter storm events/21 years. This equates to a 0.29% chance of a winter storm event in Simpson County annually.
  • In January of 2016, 1 foot of snow accumulated across Simpson County.

Because of these factors, Simpson County experiences moderate vulnerability to winter storm events. Franklin reflects Simpson County’s overall history of winter storms, and therefore experiences moderate vulnerability as well.
  • Between 2000 and 2020, NOAA and NWS reported 18 severe winter storms in Warren County.
  • On average, Warren County has experienced 6 winter storm events/21 years. This equates to a 0.29% chance of a winter storm event in Warren County annually.
  • In January of 2015, winter weather conditions caused $40,000 in property damage in Warren County.

Because of these factors, Warren County experiences moderate vulnerability to winter storm events. Bowling Green, Plum Springs, Oakland, Smiths Grove, and Woodburn reflect Warren County’s overall history of winter storms, and therefore experience moderate vulnerability as well.