Heavy rainfall from scattered thunderstorms is expected across the Southwest, Intermountain West, and Plains. Isolated dry thunderstorms may initiate additional fires across the west. The coastal Carolinas may experience flash floods in the coming days due to repeated thunderstorms. Additionally, a wave of intense summer heat will hit the Southern Plains and central Gulf Coast States this week. Read More >
Upcoming Winter Awareness Dates
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
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, Wind Chill, 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 and Wind Chill
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. |
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: 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. |
Winter Storm Warning |
When any of the following criteria is expected to occur: Snow: > 6" in 12 hours or > 8" in 24 hours 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. |
Wind Chill Advisory |
Wind Chill values are expected to be |
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. |
Wind Chill Warning |
Wind Chill values are expected to be |
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. |
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.
Extreme Cold
Extremely cold air comes every winter in at least part of the country and affects millions of people across the United States. The arctic air, together with brisk winds, can lead to dangerously cold wind chill values and life threatening conditions.
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 |
|
Hypothermia |
Shivering
Stiff Muscles
Confusion
Difficulty Speaking
Sleepiness |
|
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:
If you become stranded in your vehicle:
Outside:
Below are some tips for staying warm if you must venture outside in a winter storm or cold weather.
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:
Should you become caught outside in a violent winter storm:
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!
SciJinks: How Does Snowflakes Form? |
NSSL: Severe Weather 101 -Winter Weather |
NWS: Winter Weather Safety for You and Your Family |
NWS: Winter Safety |
NWS JetStream: Wind Chill |
NWS: Wind Chill Chart |
NWS: Wind Chill Brochure |
NWS: Cold Weather Safety |
NWS: Winter Driving Preparedness |
NWS: Winter Storms - The Deceptive Killers |
FEMA: When the Sky Turns Gray |
FEMA: Snowstorms and Extreme Cold |
FEMA: Be Prepared for a Winter Storm |
Red Cross: Winter Storm Safety |
NWS: Dressing for Cold Weather |
Owlie Skywarn: Winter Storms |
Videos
Check out these new videos created by the National Weather Service!
Winter Survival Kit for Your Vehicle
Winter Forecasting: Uncertainty
Probabilistic Snowfall Information
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Media use of NWS Web News Stories is encouraged! Please acknowledge the NWS as the source of any news information accessed from this site. |
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