{"id":1611,"date":"2022-07-10T11:07:19","date_gmt":"2024-07-10T11:25:19","guid":{"rendered":"http:\/\/ialert.com\/blog\/?p=1611"},"modified":"2026-04-28T02:13:58","modified_gmt":"2026-04-28T02:13:58","slug":"glossary-of-weather-terms-beginning-with-w","status":"publish","type":"post","link":"https:\/\/ialert.com\/blog\/weather-articles\/weather-glossary\/glossary-of-weather-terms-beginning-with-w\/","title":{"rendered":"Glossary of Weather Terms – Beginning with “W”"},"content":{"rendered":"

Confused about the difference between a Winter Storm Warning, Winter Weather Advisory, and Blizzard Warning<\/strong>? Wondering what a wind chill chart<\/strong> really means for frostbite risk, how a waterspout differs from a tornado<\/strong>, what wind shear<\/strong> does to thunderstorms, or what a whiteout<\/strong> looks like on the highway?<\/p>\n

Jump to weather terms beginning with the letter:<\/h3>\n

A<\/a> | B<\/a> | C<\/a> | D<\/a> | E<\/a> | F<\/a> | G<\/a> | H<\/a> | I<\/a> | J<\/a> | K<\/a> | L<\/a> | M<\/a> | N<\/a> | O<\/a> | P<\/a> | Q<\/a> | R<\/a> | S<\/a> | T<\/a> | U<\/a> | V<\/a> | W<\/a> | X<\/a> | Y<\/a> | Z<\/a><\/p>\n

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Weather Terms Beginning with “W”<\/strong><\/h3>\n

Waterspout<\/strong><\/h4>\n

A waterspout is a rotating column of air and water droplets extending from a cloud base to a water surface. There are two distinctly different types. Tornadic waterspouts form from a supercell thunderstorm’s mesocyclone directly over water and are every bit as dangerous as land tornadoes, they can produce winds exceeding 100 mph and should be treated with the same life-threatening urgency. Fair-weather waterspouts are weaker, non-supercell features that form on the water surface and build upward to the base of a developing cumulus cloud; they are typically EF0 intensity with winds of 40-80 mph, but still pose serious hazards to small watercraft. Fair-weather waterspouts are common along Florida’s Gulf and Atlantic coasts in summer and in the Great Lakes in autumn. When a waterspout, of either type, makes landfall, it becomes a tornado by definition. Marine Warnings are issued when waterspouts threaten harbors or near-shore areas. Small boats should never attempt to navigate through or near any waterspout.<\/p>\n

See also: Tornado Safety<\/a> | Criteria for a Tornado Warning<\/a><\/p>\n

Wet-Bulb Temperature<\/strong><\/h4>\n

The wet-bulb temperature is the lowest temperature to which air can be cooled by the evaporation of water at constant pressure. It is measured by a thermometer whose bulb is wrapped in a water-soaked wick and exposed to a moving air stream. The wet-bulb temperature lies between the dew point temperature (the lowest possible, if cooling to saturation) and the dry-bulb (regular air) temperature. It is critical for determining the rain\/snow transition line during winter storms: precipitation falls as snow when the wet-bulb temperature at the surface is at or below 32 degrees F, even if the air temperature reads slightly above freezing, which is why a forecast of 35 degrees can still mean snow accumulation. The wet-bulb globe temperature (WBGT) is also the primary measure of heat stress risk: a WBGT of 32 degrees C (90 degrees F) is considered a critical threshold for heat casualties in military and athletic contexts.<\/p>\n

Whiteout<\/strong><\/h4>\n

A whiteout is a dangerous weather condition in which blowing and drifting snow, or in extreme cases, heavy falling snow, reduces visibility to near zero while simultaneously eliminating all visual contrast between the snow-covered ground and an overcast sky. In a full whiteout, there are no shadows, no horizon, and no visual reference points of any kind, making it impossible to judge distance, direction, or depth. People caught in a ground blizzard whiteout on open terrain can become completely disoriented within seconds and may walk in circles, with fatal consequences in cold temperatures. Highway whiteouts caused by blowing snow or ground blizzards have triggered catastrophic multi-vehicle pile-ups on interstate highways across the Plains and Upper Midwest. A technical aviation whiteout can occur when an overcast sky matches the color and tone of a snow-covered surface, making terrain perception and safe landing extremely difficult even with instruments. The key safety rule in a driving whiteout: carefully pull completely off the roadway, not just to the shoulder; turn off your headlights (which can mislead following drivers); activate hazard lights only if there is no risk of being mistaken for a moving vehicle; and wait for conditions to improve.<\/p>\n

Wind Advisory<\/strong><\/h4>\n

A Wind Advisory is issued by the NWS when sustained winds of 31-39 mph or wind gusts of 46-57 mph are expected and could create hazardous conditions for driving high-profile vehicles (tractor-trailers, recreational vehicles, buses, vehicles towing trailers), cause minor property damage such as downed branches and scattered debris, and make conditions unpleasant or difficult for pedestrians and cyclists. Exact thresholds vary by NWS office and local climate, areas accustomed to frequent strong winds have higher thresholds than sheltered areas where such winds are rare. A Wind Advisory is upgraded to a High Wind Warning when sustained winds are forecast to reach 40 mph or higher, or wind gusts 58 mph or higher. A Lake Wind Advisory is issued separately for strong winds over the Great Lakes or other large bodies of water that create dangerous boating conditions but do not yet meet the threshold for a Gale Warning.<\/p>\n

Wind Chill<\/strong><\/h4>\n

Wind chill is the perceived decrease in air temperature felt by exposed human skin due to the combined effect of low temperature and wind speed. Wind accelerates heat loss from the skin through convective cooling, the faster the wind, the more rapidly body heat is stripped away. The NWS Wind Chill Index, updated to its current formula in 2001, is calculated for temperatures at or below 50 degrees F and wind speeds at or above 3 mph, using a model based on actual human facial skin cooling rates rather than the older formula based on water freezing. At an air temperature of -20 degrees F with a 30 mph wind, the wind chill index is approximately -51 degrees F, at which exposed skin can develop frostbite in under 10 minutes. The NWS issues Wind Chill Advisories when wind chills are expected to reach -10 to -24 degrees F and Wind Chill Warnings when wind chills reach -25 degrees F or lower. Prevention: cover all exposed skin, stay dry (wet clothing loses 90% of its insulating value), limit outdoor time, and watch for the early signs of frostbite, numbness, tingling, and skin that appears white or gray.<\/p>\n

See also: Wind Chill Chart<\/a> | How is Wind Chill Calculated?<\/a> | What is Frostbite?<\/a> | What is Hypothermia?<\/a><\/p>\n\n\n\n\n\n\n\n\n\n\n
Winter Storm Alert Levels Compared<\/caption>\n
Product<\/th>\nConditions<\/th>\nTimeframe<\/th>\nAction<\/th>\n<\/tr>\n<\/thead>\n
Winter Weather Advisory<\/td>\nLight mix of snow\/sleet\/freezing rain; 1-3 inches snow; 0.1-0.24 in ice<\/td>\nOccurring or imminent<\/td>\nAllow extra travel time; use caution<\/td>\n<\/tr>\n
Winter Storm Watch<\/td>\nSignificant winter weather possible; 6+ inches snow or 0.25+ in ice<\/td>\n24-48 hours out<\/td>\nPrepare emergency supplies; review plans<\/td>\n<\/tr>\n
Winter Storm Warning<\/td>\nHeavy snow (6+ inches in 12 hrs or 8+ in 24 hrs), ice, or blizzard conditions<\/td>\nOccurring or imminent<\/td>\nAvoid travel; significant threat to life\/property<\/td>\n<\/tr>\n
Blizzard Warning<\/td>\nSnow + sustained 35+ mph winds + visibility under 1\/4 mile for 3+ hours<\/td>\nOccurring or imminent<\/td>\nDo NOT travel; life-threatening conditions<\/td>\n<\/tr>\n
Ice Storm Warning<\/td>\nFreezing rain accumulation of 0.25 inch or more<\/td>\nOccurring or imminent<\/td>\nAvoid all travel; power outages likely; dangerous ice<\/td>\n<\/tr>\n
Wind Chill Warning<\/td>\nWind chills -25 degrees F or lower<\/td>\nOccurring or imminent<\/td>\nLimit outdoor exposure; frostbite in under 10 min<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Wind Direction<\/strong><\/h4>\n

Wind direction is the direction from which the wind is blowing, reported in degrees clockwise from true north in meteorological convention, or by compass direction (N, NE, E, SE, S, SW, W, NW). A critical and commonly misunderstood convention: a “southerly wind” or “south wind” blows FROM the south toward the north, it is named for where it comes from, not where it is going. Wind vanes point into the wind, indicating its direction of origin. Official NWS surface observations measure wind at the standard height of 10 meters (33 feet) above the ground. Wind direction is critically important in determining what type of air mass is being advected into an area: southerly winds bring warm, moist Gulf of Mexico air northward; northerly winds bring cold, dry Arctic air southward; easterly winds along the Gulf Coast signal onshore flow bringing moisture and potential for heavy rainfall.<\/p>\n

Wind Gust<\/strong><\/h4>\n

A wind gust is a rapid, sudden increase in wind speed significantly above the sustained (time-averaged) wind speed, typically lasting less than 20 seconds. The NWS officially defines a gust as a wind speed variation where the difference between peaks and lulls during a 2-minute observation period is at least 10 knots (approximately 11.5 mph). Gusts in severe thunderstorms regularly reach 60-80 mph; downburst events can produce gusts of 80-100+ mph over a localized area. In tropical cyclones, the maximum sustained wind (1-minute average) is used for category classification, while gusts typically run 15-25% higher. High Wind Warnings and Wind Advisories specify both sustained wind speed thresholds and separate peak gust thresholds because gusts are often what cause the most acute damage to structures, trees, and vehicles.<\/p>\n

Wind Shear<\/strong><\/h4>\n

Wind shear is any change in wind speed or direction over a short distance, either horizontally or vertically. The most meteorologically significant form is vertical wind shear, the change in wind speed and direction from the surface to the upper atmosphere. Vertical wind shear is the primary ingredient distinguishing severe, long-lived supercell thunderstorms from ordinary short-lived cells. Low-level jet streams, bands of fast wind at 1,000-5,000 feet altitude that develop over the Southern Plains on warm nights, provide intense low-level wind shear that dramatically enhances tornado potential in the overnight and early morning hours. For aviation, wind shear near airports creates sudden, dangerous changes in an aircraft’s airspeed during the critical phases of takeoff and landing. Several major airliner crashes in the 1970s and 1980s were attributed to microburst-induced wind shear, leading to the development of Terminal Doppler Weather Radar (TDWR) at major airports for low-level wind shear detection.<\/p>\n

Winter Storm Warning<\/strong><\/h4>\n

A Winter Storm Warning is issued by the NWS when hazardous winter weather conditions are occurring or expected within 12-24 hours that meet or exceed criteria varying by region. The typical national threshold is 6 inches of snow in 12 hours, 8 inches of snow in 24 hours, or significant ice accumulation of 0.25 inch or more. In areas of the South and lower Mid-Atlantic that are unaccustomed to winter weather and lack the infrastructure to cope with it, lower thresholds apply, even 2-3 inches of snow can trigger a Winter Storm Warning if roads are likely to become impassable. During a Winter Storm Warning, all unnecessary travel should be avoided. Prepare at home by having at least 3 days of emergency supplies: food, water, medications, extra blankets, a battery-powered or hand-crank weather radio, and backup heat sources. Keep your vehicle’s fuel tank at least half full to prevent fuel line freezing and to ensure you can run the heater if stranded.<\/p>\n

See also: Winter Storms, A Preparedness Guide<\/a> | Winter Storm Watch vs Warning vs Advisory<\/a> | OSHA Safe Winter Driving<\/a><\/p>\n

Winter Storm Watch<\/strong><\/h4>\n

A Winter Storm Watch is issued when the potential for a significant winter weather event exists within 24-48 hours but conditions are favorable rather than certain, a Watch means the National Weather Service believes there is a good chance of a storm but details of timing, track, and intensity are not yet locked in. The Watch is the time to act before the storm: buy emergency supplies now (stores will sell out of essentials), check vehicle condition (battery, antifreeze, wiper blades, tires), review plans for school and work closures, identify backup shelter, and charge all electronic devices. A Winter Storm Watch is typically updated to a Winter Storm Warning approximately 12-24 hours before onset as the forecast becomes more certain. Occasionally, a Watch is canceled if the storm tracks away or fails to materialize, but treating a Watch as a guarantee is far safer than ignoring it.<\/p>\n

Winter Weather Advisory<\/strong><\/h4>\n

A Winter Weather Advisory is issued when winter weather conditions are expected to cause significant inconvenience and may be hazardous to travelers, but do not meet the threshold for a Winter Storm Warning. A Winter Weather Advisory typically covers expected snowfall of 1-3 inches, light freezing rain or drizzle that could ice over bridges and overpasses, patchy frost, or blowing snow that reduces visibility. The key message of a Winter Weather Advisory is: roads will be slippery, allow extra travel time, and use caution. It is the lowest tier of the NWS three-level winter weather alert system (Advisory at the base, then Watch for advance notice, then Warning for imminent or occurring dangerous conditions). Even an Advisory should not be dismissed, a thin glaze of freezing rain from a “mere” Winter Weather Advisory has caused multi-vehicle highway accidents killing dozens of people.<\/p>\n

Straight-Line Wind Damage vs. Tornado Damage<\/strong><\/h4>\n

Distinguishing between tornado damage and straight-line wind damage from a thunderstorm downdraft or derecho is a critical post-storm task for NWS damage survey teams, since each type generates a separate official record. Tornado damage characteristics: debris and tree falls radiating outward from a central path, pointing toward a central line from multiple different directions; curved or arcing damage swaths; structures impacted from varying directions simultaneously (a roof blown off in one direction while an adjacent wall was pushed from a different direction). Straight-line wind damage characteristics: all debris and tree falls consistently in one direction, parallel to the wind vector; linear or slightly fan-shaped damage pattern; consistent structural damage direction across the affected area. Dual-polarization Doppler radar velocity signatures also help distinguish rotating (tornado) from non-rotating (straight-line wind) events in real time. Official NWS tornado counts depend on accurate post-storm damage surveys confirming rotation.<\/p>\n

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Frequently Asked Questions, “W” Weather Terms<\/strong><\/h3>\n

What is the difference between a Winter Storm Warning, Winter Weather Advisory, and Blizzard Warning?<\/h4>\n

These are three different tiers of winter weather alerts. A Winter Weather Advisory means winter conditions will cause inconvenience and hazardous driving but are below storm thresholds, typically 1-3 inches of snow or light freezing rain. A Winter Storm Warning means heavy snow (6+ inches in 12 hours or 8+ in 24 hours), significant ice, or other serious winter hazards are occurring or imminent, avoid travel. A Blizzard Warning is the most specific: it requires snow combined with sustained winds of 35+ mph AND visibility under 1\/4 mile for 3 or more consecutive hours, conditions that are life-threatening in open areas.<\/p>\n

What is wind chill and how quickly can it cause frostbite?<\/h4>\n

Wind chill is the perceived temperature based on the combined effect of cold air and wind, which accelerates heat loss from exposed skin. At -20 degrees F with 30 mph winds, the wind chill is about -51 degrees F, exposed skin can develop frostbite in under 10 minutes. At -40 degrees F wind chill, frostbite can develop in under 5 minutes. The NWS issues Wind Chill Advisories when wind chills are expected to reach -10 to -24 degrees F and Wind Chill Warnings when they reach -25 degrees F or lower. Key prevention: cover all exposed skin, limit outdoor time, and stay dry, wet clothing loses 90% of its insulating value.<\/p>\n

What is the difference between a waterspout and a tornado?<\/h4>\n

A waterspout is a rotating column of air and condensation extending from a cloud to a water surface. Tornadic waterspouts form from a supercell’s mesocyclone over water and are just as dangerous as land tornadoes. Fair-weather waterspouts are weaker columns that form at the water surface and build upward to a growing cumulus cloud, typically EF0 intensity with winds of 40-80 mph. If a tornadic waterspout moves ashore, it becomes a tornado. Fair-weather waterspouts are common along Florida’s coasts in summer and in the Great Lakes in fall and spring. Small boats should never attempt to navigate through or near a waterspout.<\/p>\n

What is wind shear and why does it matter?<\/h4>\n

Wind shear is any change in wind speed or direction over distance or altitude. Vertical wind shear, wind changing speed and direction from the surface to the upper atmosphere, is the single most critical ingredient for tornado-producing supercell thunderstorms. Low-level jet streams that develop over the Southern Plains at night (speeds of 30-70 mph at 2,000-3,000 feet altitude) provide intense low-level shear that dramatically increases tornado potential. For aviation, wind shear near airports creates sudden, dangerous changes in airspeed during takeoff and landing. Several major airliner crashes have been attributed to microburst-induced wind shear.<\/p>\n

What should you do when a Winter Storm Warning is issued?<\/h4>\n

When the NWS issues a Winter Storm Warning, you should avoid all unnecessary travel during the warning period. If you must travel, carry an emergency kit including blankets, extra clothing, food, water, a flashlight, jumper cables, a snow brush and ice scraper, sand or kitty litter for traction, and a fully charged phone. At home, have at least 3 days of emergency supplies including food, water, medications, a battery-powered or hand-crank radio, and backup heat sources. Keep your vehicle’s fuel tank at least half full to prevent fuel lines from freezing and to ensure you can evacuate or run the heater if stranded.<\/p>\n

What is a whiteout and how dangerous is it?<\/h4>\n

A whiteout is a condition caused by blowing and drifting snow so dense that visibility drops to near zero while simultaneously eliminating all contrast between the snow-covered ground and an overcast sky. In a whiteout, there are no shadows, no horizon, and no visual reference points, making it impossible to judge distance, direction, or depth. People caught in a ground blizzard whiteout can become completely disoriented within seconds and walk in circles. Highway whiteouts have caused catastrophic multi-vehicle pile-ups. If driving and a whiteout develops, carefully pull completely off the road, turn off your lights, put on your hazard lights only if you cannot be mistaken for a moving car, and wait.<\/p>\n

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