Sioux Falls, SD

Weather Forecast Office

Winter Preparedness

Upcoming Winter Awareness Dates

South Dakota - Winter Awareness Day - October 23, 2024

Iowa - Winter Awareness Day - November 7, 2024

Nebraska - Winter Awareness Day - November 7, 2024

Minnesota - Winter Awareness Week - November 18-22, 2024

Introduction

The weather has a habit of changing pretty quickly, especially during the winter season. Powerful winter 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 a moderate snow over a few hours to a massive blizzard with blinding, wind-driven snow that lasts 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 chart 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.

How the National Weather Service Keeps You Informed

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 & 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, Ice 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

Below is a break down the different alerts issued by the National Weather Service in Sioux Falls.

Product	What It Means	What You Should Do
Hazardous Weather Outlook	Will there be any hazardous winter weather in the next several days?	If any hazardous winter weather is expected, check back for later forecasts, information, and possible watches. Latest Hazardous Weather Outlook
Winter Weather Advisory	When any of the following criteria is expected to occur: Snow: > 3" to < 6" in 12 hours or 5" to 8" in 24 hours Sleet: Less than 1/2 inch in the next 24 hours Ice: Less than 1/4 of an inch Blowing Snow: Visibility occasionally reduced to 1/4 of a mile due to blowing snow with winds less than 35 mph.	On the Road: Unplowed/less traveled roads may be slick, so drive with caution. If blowing snow is occurring, drive at a safe speed and leave plenty of space between you and other drivers. At Home: Make sure you have the proper snow removing equipment to clear your sidewalks and driveways.
Winter Storm Watch	Alerts the public to the possibility of severe winter conditions. Watches are typically issued anywhere from 12 to 48 hours in advance of a winter storm. However, in some circumstances, watches may be issued longer than 48 hours in advance.	On the Road: Consider changing your travel plans. If you must drive, carry a winter survival kit in your car and be prepared for delays. At Home: Make sure you have the proper snow removing equipment to clear your sidewalks and driveways. If an exceptionally high amount of snow is forecast, be prepared to remain at home for a day or two.
Winter Storm Warning	When any of the following criteria is expected to occur: Snow: > 6" Sleet: 1/2 inch or more	On the Road: Seriously consider postponing any non-essential driving. If you must drive, carry a winter survival kit in your car and be prepared for delays. At Home: Make sure you have the proper snow removing equipment to clear your sidewalks and driveways. If an exceptionally high amount of snow is forecast, be prepared to remain at home for a day or two.
Cold Weather Advisory	Apparent temperature values are expected to be <= -25°F for all areas, except: Dakota and Dixon Counties in NE and Woodbury and Ida Counties in IA where values are expected to be <= -20°F	On the Road: Pack extra clothes and blankets in addition to your winter survival kit in your car in case you become stranded. At Home: If you go outdoors, dress accordingly by wearing well-insulated hats and gloves and putting on extra layers of clothing to keep warm. Frostbite could take place in as little as 30 minutes.
Extreme Cold Warning	Apparent temperature values are expected to be <= -35°F for all areas, except: Dakota and Dixon Counties in NE and Woodbury and Ida Counties in IA where values are expected to be <= -25°F	On the Road: Pack extra clothes and blankets in addition to your winter survival kit in your car in case you get stranded. At Home: Seriously consider postponing any outdoor plans. Wear well insulated clothing if you must go outdoors. Frostbite could take place in as little as 10 minutes.
Ice Storm Warning	Significant ice accumulations > 1/4 inch	On the Road: Refrain from driving except in emergency situations. Roads will likely be treacherous and maintaining control of your car will be very difficult. At Home: Be prepared for possible long duration power outages and refrain from walking on ice covered surfaces outside.
Blizzard Warning	Sustained wind or frequent gusts greater than or equal to 35 mph will accompany falling and/or blowing snow to frequently reduce visibility to less than or equal to 1/4 mile for three or more hours.	On the Road: Refrain from driving except in emergency situations, especially in open country. Always carry a winter survival kit in your car if you must drive. High winds and white-out conditions will make driving extremely dangerous. At Home: Be prepared to remain at home for a few days, especially if you live in a rural area. Snow drifts may be higher than 10 feet, so make sure you have the proper snow removing equipment.
Snow Squall Warning	Intense, but limited duration, periods of moderate to heavy snowfall, accompanied by gusty surface winds resulting in reduced visibilities and whiteout conditions.	On the Road: Be prepared to encounter these dangerous travel conditions and delay or adjust travel plans as possible. Always carry a winter survival kit in your car if you must drive. High winds and white-out conditions will make driving extremely dangerous. At Home: Remain at home until the short duration heavy snow band has ended and travel conditions have improved.

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 2024-2025 winter, the NWS 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 NWS Hazard Simplification Program. For more details, please see this fact sheet.

Wind Chill

What is the Wind Chill Temperature?

It 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.

Wind Chill Chart

The Wind Chill Chart above includes a frostbite indicator, showing the points where temperature, wind speed and exposure time will produce frostbite on humans. The chart above includes three shaded areas of frostbite danger. Each shaded area shows how long (30, 10 and 5 minutes) a person can be exposed before frostbite develops.

For example, a temperature of 0°F and a wind speed of 15 mph will produce a wind chill temperature of -19°F. Under these conditions, exposed skin can freeze in 30 minutes.

Note: Wind chill temperature is only defined for temperatures at or below 50°F and wind speeds above 3 mph. Bright sunshine may increase the wind chill temperature by 10 to 18°F.

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.

Symptoms and First Aid

Symptoms

First Aid

Frostbite

Discolored skin (flushed, white, greyish-yellow, blue)

Skin that feels unusually firm or waxy

Numbness

Handle the affected area gently and do not rub it.
Warm slowly by soaking the affected area in warm (not hot) water until it appears red and feels warm.
Loosely bandage the affected area with dry, sterile dressings. If the person's fingers or toes are frostbitten, place dry, sterile gauze between them to keep them separated.
Avoid breaking any blisters and do not allow the affected area to refreeze.

Hypothermia

Shivering

Stiff Muscles

Confusion

Difficulty Speaking

Sleepiness

If your temperature is 96°F or less, you feel cold and sluggish, or are having trouble thinking clearly, see your doctor immediately or go to the nearest emergency room!
Otherwise, gently move the person to a warm place, remove any wet clothing, and dry the person. Give them rescue breathing or CPR if needed.
Warm the core first (trunk, abdomen), not the extremities (hands, feet). Warming extremities first could cause shock, or drive cold blood towards the heart, causing heart failure. Hot water bottles or hot packs may be used to help warm, but must be wrapped in a towel or blanket before applying.

Safety

Being safe in dangerous winter weather means not only to taking the appropriate steps during the storm, but also having the right supplies beforehand. If you wait to stock up on supplies until a watch or warning is issued, you run the risk of the supplies being out of stock or the store being closed.

At Home:

Beforehand

The checklist below provides some basic guidance on what to have in your house/apartment during the winter should you be trapped by the snow or lose electricity. This is not an exhaustive list.

Food and water are vital necessities during a winter storm; however, these foods should be safe to consume should power be lost. Use the checklist below to help stock your shelves.

**If permissible, a generator is a valuable asset to power key household appliances. Carefully follow all directions provided with the generator!**

Additional information on assembling home disaster kits can be found on the FEMA website.

During the Event

During severe winter weather, the best advice is to stay inside your house. Plummeting temperatures and high winds that often accompany winter storms allow frostbite and hypothermia to set in quickly if you are outside. Also, road conditions will likely be very treacherous, especially if you live in rural areas. Monitor local media outlets for the latest information on the storm.

In Your Vehicle:

Beforehand

Each fall, take the time to go through your vehicle and winterize it.

More importantly, make sure you carry a winter survival kit in your car in case you get stranded. You can use a large plastic tote or box to hold all of the needed items. If you already have one in your car, go through it and make sure it is fully stocked and ensure that any perishable items are still good to use. Items that should be in a winter survival kit are covered in the checklist below.

During the Event

If you must drive during or immediately after a winter storm:

Check road conditions by calling 511.
Travel in the day and do not travel alone.
Stay on the main roads and avoid back road shortcuts.
Let someone know your destination, your route, and when you expect to arrive.
Drive cautiously and leave plenty of space between you and the car ahead of you.

If you become stranded in your vehicle:

Break out your emergency winter survival kit!
Turn on your hazard lights and hand a distress flag from the radio antenna or window.
Remain in your vehicle where rescuers can find you, unless a shelter is VERY close.
Periodically run the engine and heater for about 10 minutes every hour to keep warm.
Check the exhaust pipe periodically and slightly open a downwind window to avoid carbon monoxide poisoning.
Eat and drink regularly but avoid caffeine and alcohol.
Exercise to maintain body heat but avoid overexertion.
Turn on the inside light at night so work crews or rescuers can see you.
Take turns sleeping with one person awake at all times to look for rescue crews.
Once the storm passes, leave the car and proceed on foot, if necessary.

Outside:

Below are some tips for staying warm if you must venture outside in a winter storm or cold weather.

Wear several layers of loose-fitting, lightweight, warm clothing (shirts, pants, socks, etc.) rather than one layer of heavy clothing. The outer garments should be tightly woven and water repellent.
Wear mittens, which are warmer than gloves.
Wear a hat which will prevent the loss of body heat.
Cover your mouth with a scarf to protect your lungs.
Avoid overexertion, such as shoveling heavy snow, pushing a car, or walking in deep snow. The strain from the cold and the hard labor may cause a heart attack. Sweating could lead to a chill and hypothermia.

If you are planning to take a hunting, camping, or other extended outdoor trip in the mid fall to mid spring timeframe, pay attention to the weather in the days leading up to the trip. If severe winter weather is forecast, consider postponing the trip. If you do head out:

Pack extra warm clothes, such as coats, hats, and mittens, as well as an additional change of regular clothes should you get wet. Many times, especially in the fall, warm summer-like weather can precede a dangerous winter storm, lulling people into a false sense of security.
Let friends and family know your travel plans and carry a cell phone. Ask people back home to routinely check the weather and call you if conditions are expected to deteriorate.
If you own a smartphone and have internet access at your location, you can use your phone to check on the latest weather conditions and if any watches and/or warnings are issued.
Carry a portable radio or NOAA Weather Radio to check on weather conditions.

Should you become caught outside in a violent winter storm:

If a building or structure is nearby (less than a quarter of a mile away), seek shelter there.
If there is not shelter nearby, Stay Put! You could become disoriented by the blinding snow.
Build a lean-to or hollow out a snow save to shield yourself from the wind.
Stay dry and cover all exposed parts of the body.
Start a fire for heat and to attract attention. Place rocks around the fire to absorb and reflect heat.
Do not eat snow because it will lower your body temperature. Melt it first.

Educational Materials

Winter storms can bring snow, sleet, and freezing rain across the entire United States and its territories. In some cases the temperature can drop over 50 degrees in a matter of hours. Refer to the resources below to learn how winter storms form, and how you can keep you and your family safe!