Bob Hill is the Brookings County emergency manager.

This week will feature information I have gathered from the National Weather Service over the years regarding severe winter weather.

The weather has a habit of changing quickly, especially during winter. Powerful storms driven by jet streams that often exceed 200 mph can bring copious amounts of snow and ice, along with blowing snow and whiteout conditions. In some cases the temperature can drop over 50 degrees in a matter of hours. Whether it be exposure to the cold, vehicle accidents caused by slick roads or fires resulting from the improper use of heaters, hundreds of people are injured or killed each year as a direct result of winter weather.  

Winter storms range from moderate snow over a few hours to massive blizzards that last for several days. Some winter storms are large enough to affect several states while others affect only a single community.

High winds, freezing rain or sleet, heavy snowfall, and dangerously cold temperatures are the main hazards associated with winter storms. Impassable snow drifts can maroon people at home without utilities or other services for days after an event. Heavy snowfall and blizzards easily trap motorists in their vehicles and make walking to find help a deadly effort. Bitter cold temperatures and wind chills during and after a winter storm can lead to hypothermia and kill anyone caught outside for too long. The aftermath of a winter storm can impact a community or region for days, weeks or even months, incurring steep economic costs.

The information below shows how the different types of winter precipitation are formed.

• Snow: Frozen precipitation that never melts during its descent to the surface
• Sleet: Frozen precipitation falls through a warm layer and melts, then falls through another cold layer that is deep enough to refreeze the raindrops into pellets before hitting the ground.
• Freezing rain: Frozen precipitation falls through a warm layer and melts, then falls on surfaces that are below freezing and solidifies, resulting in an even coating of ice on streets, trees, cars, and power lines.
• Rain: Frozen precipitation that falls through a deep warm layer and melts into liquid before reaching the ground. Water droplets are classified as rain if they are 0.5 millimeters or greater in size, whereas droplets smaller than 0.5 millimeters are classified as drizzle. 

The National Weather Service issues four “tiers” of alerts to inform you of incoming hazardous weather. Please take a moment to review and understand the differences between them.

Outlook

• Timing: Up to seven days out
• Issued when significant winter weather is possible, but not guaranteed — a “heads-up”
• You should: Monitor forecasts for additional information
• Types of outlooks: Hazardous weather outlooks and weather story graphic

Watch

• Timing: Two to three days before the event
• Increasing confidence that dangerous winter weather which could threaten life and property will occur
• You should: Start taking necessary precautions in case the event happens
• Types of watches: Winter storm, extreme cold watch

Warning

• Timing: Within 24 to 48 hours of the event
• High confidence of a winter weather event which could threaten life and property — is the most serious of alerts
• You should: Continue and finish preparing for the storm as well as monitor for updated warning statements
• Types of warnings: Winter storm, blizzard, iIce storm, extreme cold, and snow squall

Advisory

• Timing: Within 24 to 36 hours of the event
• Events not expected to pose a significant risk to life & property, but could still impact travel or other activities
• You should: Exercise caution when traveling and be prepared for any possible impacts
• Types of advisories: Winter weather, cold weather

Extreme cold

Extremely cold air comes every winter in at least part of the country and affects millions of people across the United States. Extreme cold can come with (wind chill) or without wind — cold is cold and can quickly become life threatening if the proper precautions aren’t followed. 

New for the 2024-25 winter, the weather service will no longer issue wind chill warnings or wind chill advisories. Instead, extreme cold warnings and cold weather advisories will be issued, which are based on apparent temperature. Apparent temperature is the ambient air temperature when there is no wind (calm conditions) or the wind chill when there is wind. These changes are part of the weather service's Hazard Simplification Program.  

Wind chill

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.

Frostbite

Occurs when the body’s survival mechanisms kick in during extremely cold weather. To protect your vital inner organs, the body will cut off the circulation to your extremities: fingers, toes, nose, ears, etc., which will eventually freeze and cause damage to body tissue. This can occur within a matter of minutes during extremely cold temperatures if exposed skin is improperly protected.  

 Hypothermia

Is caused by prolonged exposure to very cold temperatures and occurs when a person’s body temperature drops below 96°F. While hypothermia is most likely to occur at very cold temperatures, it can also occur at cool temperatures (above 40°F) if a person become chilled from rain, sweat, or submersion in cold water.

 If you or someone you care about must venture outdoors during extreme cold this winter, dress in layers. Cover exposed skin to reduce your risk of frostbite or hypothermia. Try to seek shelter from the wind as much as possible while outside. Once inside again, change into dry clothing immediately if you are wet.

To be continued next week; until then, remember to Keep an Eye On the Sky.

Bob the EM