Winter Storm Warnings


A. Warning Responsibility

The National Weather Service is responsible for the timely issuance of weather warnings to the public, including the approach of winter storms.

Know what winter storm WATCHES and WARNINGS mean:

WINTER STORM WATCH: Severe winter conditions, such as heavy snow and/or ice, are possible within the next day or two. Prepare now!

WINTER STORM WARNING: Severe winter conditions have begun or are about to begin in your area. Stay indoors!

BLIZZARD WARNING: Snow and strong winds will combine to produce a blinding snow(near zero visibility), deep drifts, and life-threatening wind chill. Seek refuge immediately!

WINTER WEATHER ADVISORY: Winter weather conditions are expected to cause significant inconveniences and may be hazardous. If caution is exercised, these situations should not become life-threatening. The greatest hazard is often to motorists.

FROST/FREEZE WARNING: Below freezing temperatures are expected and may cause significant damage to plants, crops, or fruit trees. In areas unaccustomed to freezing temperatures, people who have homes without heat need to take added precautions.

B. Definitions

Ice Storm-Freezing rain or drizzle is called an ice storm. Moisture falls in liquid form but freezes upon impact. The term "heavy" is used to indicate an ice coating sufficiently heavy to cause significant damage to trees, overhead wires, and similar objects.

Snow-"Snow" is a forecast, without a qualifying word such as "occasional" or "intermittent," means that the fall of snow is of a steady nature and will probably continue for several hours without letup.

"Heavy snow warnings" are issued to the public when a fall of four inches or more is expected in a 12-hour period, or a fall of six inches or more is expected in a 24-hour period. Some variations on these rules may be used in different parts of the country. Where four-inch snowfalls are common, the emphasis on heavy snow is generally associated with six or more inches of snow. In other parts of the country where heavy snow is infrequent, or in metropolitan areas with heavy traffic, a snowfall of two or three inches will justify a heavy snow warning.

"Snow Flurries" are defined as snow falling for short durations at intermittent periods; however, a snowfall during the flurries may reduce visibilities to an eighth of a mile or less. Accumulations from snow flurries are generally small.

"Snow squalls" are brief, intense falls of snow and are comparable to summer rain showers. They are accompanied by gusty surface winds.

"Blowing and drifting snow" generally occur together and result from strong winds and falling snow or loose snow on the ground. "Blowing snow" is defined as snow lifted from the surface by the wind and blown about to a degree that horizontal visibility is greatly restricted.

"Drifting snow" is used in forecasts to indicate that strong winds will blow falling snow or loose snow on the ground into significant drifts. In the northern plains, the combination of blowing and drifting snow, after a substantial snowfall has ended, is often referred to as "ground blizzard."

"Blizzards" are the most dramatic and perilous of all winter storms, characterized by low temperatures and by strong winds bearing large amounts of snow. Most of the snow accompanying a blizzard is in the form of fine, powdery particles of snow which are whipped in such great quantities that at time visibility is only a few yards.

"Blizzard warnings" are issued when winds with speeds of at least 35 mph are accompanied by considerable falling or blowing snow and temperatures of 20 degrees F or lower are expected to prevail for an extended period of time.

"Severe blizzard warnings" are issued when blizzards of extreme proportions are expected and indicate wind withe speeds of at least 45 mph plus a great density of falling or blowing snow and a temperature of 10 degrees F or lower.

A "cold-wave warning" indicates an expected rapid fall in temperature within a 24-hour period which will require substantially increased protection to agricultural, industrial, commercial, and social activities. The temperature falls and minimum temperatures required to justify cold wave warnings vary with the changing of the season and with geographic location. Regardless of the month or the section of the country, a cold wave warning is a red flag alert to the public that during a forthcoming forecast period a change to very cold weather will require greater that normal protective measures.

"Hazardous Driving (Travelers') Warnings" are issued to indicate that falling, blowing, or drifting snow, freezing rain or drizzle, sleet or strong winds will make driving difficult.

"Stockmen's Warnings" alert ranchers and farmers that livestock will require protection from a large accumulation of snow or ice, a rapid drop in temperatures, or strong wind.

Wind Chill Factor-Strong winds combined with low temperatures cause a very rapid cooling of exposed surfaces. Unprotected portions of the body, such as the face or hands, can chill rapidly and should be protected as much as possible from the cold wind. A very strong wind combined with a temperature slightly below freezing can have the same chilling effect as a temperature nearly 50 degrees F lower in a calm atmosphere. Arctic explorers and military experts have developed a term called the "wind chill factor," which states the cooling effect of various wind and temperature combinations. In certain areas, the Weather Service issues this information as the "wind chill index." The following descriptive scale compares a 20 degrees F temperature with different wind speeds.

Wind with


20 Degrees F

Wind-Chill Index






----------- --------------- -----------
10 MPH 2 Degrees F Very Cold
20 MPH -9 Degrees F Bitter Cold
30 MPH -20 Degrees F Extreme Cold

Winter Storm Safety Rules-Keep ahead of a winter storm by listening to the latest National Weather Service warning and bulletins on radio and television.

BE PREPARED...Before the Storm Strikes:

Check battery powered equipment. A portable radio or television set may be your only contact with the world outside the winter storm. Also, check emergency cooking facilities and flashlights. Have extra batteries.

Check your supply of heating fuel. Fuel carriers may not be able to make deliveries if a winter storm buries your area in snow.

Check your food and stock an extra supply. Your supplies should include food that requires no cooking or refrigeration in case of power failure.

Have an emergency heating source available, such as a fireplace, wood stove, space heater, etc. Learn to use properly to prevent a fire hazard due to overheated coal or oil-burning stoves, fireplaces, heaters, etc. Have proper ventilation.

Check fire extinguisher and smoke detector to ensure they are working properly.

Check your supply of any necessary medications, first-aid items, and baby items.

Stay indoors during storms and cold snaps unless in peak physical condition. If you must go out, avoid over-exertion.

Don't kill yourself shoveling snow. It is extremely hard work for anyone in less than prime physical condition, and can bring on a heart attack, a major cause of death during and after winter storms.

Rural residents: Make necessary trips for supplies before the storm develops or not at all. Arrange for emergency heat supply in case of power failure. Be sure camp stoves and lanterns are filled.

Dress to fit the season-If you spend much time outdoors, wear loose-fitting, lightweight, warm clothing in several layers; layers can be removed to prevent perspiring and subsequent chill. Outer garments should be tightly woven, water repellent, and hooded. The hood should protect much of your face and cover your mouth to ensure warm breathing and protect your lungs from the extremely cold air. Remember that entrapped, insulating air, warmed by body heat, is the best protection against cold. Layers of protective clothing are more effective and efficient than single layers of thick clothing. Mittens, snug at the wrists, are better protection than fingered gloves.

Your automobile can be your best friend--or worst enemy--during winter storms, depending on your preparations. Get your car "winterized" before the storm season begins. Everything on the checklist shown below should the taken care of before winter storms strike your area:

Ignition System




Tight Exhaust System

Snow Tires Installed




Cooling System



Fuel System

Wiper Blades

Winter-Grade Oil

Winter Storm Car Kit-Be equipped for the worst. Carry a winter storm car kit, especially if cross country travel is anticipated or if you live in the northern states.

The kit should contain blankets or sleeping bags; matches and candles; empty 3-pound coffee can and plastic cover, with tissues and paper towels for sanitary purposes; a smaller can and water-proof matches to melt snow for drinking water; water container; extra clothing; high- calorie, nonperishable food; compass and road maps; knife; first aid kit; shovel; sack of sand(or cat litter); flashlight or signal light with extra batteries; windshield scraper; booster cables; two tow chains; fire extinguisher; axe; and a tool kit.

Winter travel by automobile is serious business. Keep these points in mind, especially for severe storms:

1. If the storm exceeds or even tests your limitations, seek available refuge immediately.

2. Plan your travel and select primary and alternate routes.(Let someone know your plans.)

3. Check latest weather information on your radio.

4. Try not to travel alone; two or three persons are preferable.

5. Travel in a convoy with other vehicles, if possible.

6. Always fill your gasoline tank before entering open country, even for a short distance.

7. Drive carefully, defensively.

Trapped by a Blizzard in a Vehicle

Avoid overexertion and exposure. Exertion from attempting to push your car, shoveling heavy drifts, and performing other difficult chores during the strong winds, blinding snow, and bitter cold of a blizzard may cause a heart attack-even for persons in apparently good physical condition.

Stay in your vehicle. Do not attempt to walk out of a blizzard. Disorientation comes quickly in blowing and drifting snow. Being lost in open country during a blizzard is almost certain death.

Don't panic.

Keep fresh air in your car. Freezing wet snow and wind-driven snow can completely seal the passenger compartment.

Beware the gentle killer: Carbon monoxide and oxygen starvation. Run the motor and heater sparingly, and only with the downwind window open for ventilation.

Exercise by clapping hands and moving arms and legs vigorously from time to time, and do not stay in one position for long.

Turn on dome light at night, to make the vehicle visible to work crews.

Keep watch. Do not permit all occupants of a car to sleep at once.

Livestock-Blizzards take a terrible toll in livestock. For both humane and economic reasons, stockmen should take necessary precautions in advance of severe winter storms.

Move livestock, especially young livestock, into sheltered areas (frequently called "shelter belts") properly oriented and laid out. These provide better protection for range cattle than shed- type shelters, which may cause cattle to overcrowd, with consequent overheating and respiratory disorders.

Haul extra feed to feeding areas before the storm arrives. Storm duration is the largest determinant of livestock losses; if the storm lasts more than 48 hours, emergency feed methods are required. Range cattle are hardy and can survive extreme winter weather providing they have some non confining type of shelter from the wind and are able to feed at frequent intervals.

Autopsies of cattle killed by winter storms have shown the cause of death to be dehydration, not cold or suffocation. Because cattle cannot lick enough snow to satisfy their thirst, stockmen are advised to use heaters in water tanks to provide livestock with water and feed after prolonged exposure to winter storm conditions.