A weather warning generally refers to an alert issued by a meteorological agency to warn citizens of approaching dangerous weather. A weather watch, on the other hand, typically refers to an alert issued to indicate that conditions are favorable for the development of dangerous weather patterns, although the dangerous weather conditions themselves are not currently present.
The Bureau of Meteorology is responsible for issuing weather warnings in Australia. The Bureau's warnings can be separated into severe thunderstorm warnings and severe weather warnings. Severe thunderstorm warnings are issued when either a severe thunderstorm is reported or if existing thunderstorms are expected to become severe. [1] Severe weather warnings are issued when severe weather is occurring or expected in an area, which are not solely related to severe thunderstorms. [2]
In Canada, governmental weather warnings and watches are issued by the Environment Canada. Environment Canada defines an advisory as "an alert to cover a wide array of deteriorating weather conditions," a watch as "when conditions favour that severe weather forming" and a warning as "severe weather is actually occurring or is imminent." [3] Additionally, Environment Canada breaks down weather alerts based upon the specific type of hazardous weather. These alerts are regionally issued throughout Canada and include, but are not limited to, winter storms, extreme temperature(including tornadoes), wind, tsunami, tropical cyclones, and extreme precipitation amounts.
MetService is the National Meteorological Service of New Zealand, and is designated by the Minister of Transport to provide New Zealand's authorised meteorological warning service. [4] MetService issues Severe Weather Outlooks, Watches and Warnings under a Code of Practice that enables others to distribute this information in the national interest. Like the United States NWS, MetService breaks down weather warnings and watches based on the specific type of hazardous weather – heavy rain, heavy snow, severe gales, and other weather likely to cause significant disruption to the general public or specific industry groups. MetService also provides Severe Thunderstorm Outlooks, Watches, and Warnings to deal with heavy rain and strong wind gusts caused by thunderstorms, as well as large hail and damaging tornadoes.
In the Philippines, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) issues rainfall advisories, thunderstorm advisories, gale warnings, flood warnings, and tropical cyclone wind signals.
The Swedish Meteorological and Hydrological Institute uses terminology based on other countries. Yellow level means forecast of weather that can mean some risks and disturbances to transport and other parts of society. Amber level is for weather that can mean danger, damage, and larger disturbances. Red level is for weather that can mean big danger, serious damage, and major disturbances. This can refer to many types of weather related events such as wind, flooding, snow, forest fires, etc. Sweden does not have as severe weather as some other countries, so red events in Sweden would normally not cause large international headlines.
Until 2021 the SMHI its own warning level terminology, Class 1, 2 and 3, fairly much corresponding to Yellow, Amber and Red.
The Met Office, the United Kingdom's national weather service, does not issue separate weather warnings and watches, but has an analogous system of flash warnings and advance warnings that serve the same general role of weather warnings and weather watches, respectively. Other official meteorological departments may use similar systems but use different terms.
The Met Office and other weather services have three colour coded warning levels:
Thunderstorm warnings both Severe and Watch are also issued as of 2018.
In the United States, governmental weather warnings and watches are issued by the National Weather Service, which is itself a branch of the National Oceanic and Atmospheric Administration. The NWS defines a watch as "the risk of hazardous weather or hydrologic event [increasing] significantly, but its occurrence, location, and/or timing is still uncertain" and a warning as "hazardous weather or hydrologic event [that] is occurring, is imminent, or has a very high probability of occurring". [5] Additionally, the NWS breaks down weather warnings and watches based upon the specific type of hazardous weather. These warnings and watches include, but are not limited to, flooding, severe local storms, tropical cyclones, and winter storms.
A tornado warning is a public warning that is issued by weather forecasting agencies to an area in the direct path of a tornado, or a severe thunderstorm capable of producing one, and advises individuals in that area to take cover. Modern weather surveillance technology such as Doppler weather radar can detect rotation in a thunderstorm, allowing for early warning before a tornado develops. They are also commonly issued based on reported visual sighting of a tornado, funnel cloud, or wall cloud, typically from weather spotters or the public, but also law enforcement or local emergency management. When radar is unavailable or insufficient, such ground truth is crucial. In particular, a tornado can develop in a gap of radar coverage, of which there are several known in the United States.
A tornado watch is a statement issued by weather forecasting agencies to advise the public that atmospheric conditions in a given region may lead to the development of tornadoes within the region over a period of several hours. In addition to the potential for tornado development, thunderstorms that develop within the watch area may contain large hail, straight-line winds, intense rainfall and/or flooding that pose a similar damage risk as the attendant tornado threat.
A severe thunderstorm watch is a statement issued by weather forecasting agencies to advise the public that atmospheric conditions in a given region may lead to the development of severe thunderstorms within the region over a period of several hours. The criteria for issuing a watch varies by country, and may also include torrential rainfall and tornadoes. A watch may also be issued several hours ahead of the arrival of a mature and organized complex of storms, or more clustered or discrete storm activity.
A severe thunderstorm warning is a type of public warning for severe weather that is issued by weather forecasting agencies worldwide when one or more severe thunderstorms have been detected by Doppler weather radar, observed by weather spotters, or reported by an emergency management agency, law enforcement, or the general public. Unlike a watch, a warning is issued to areas in the direct path of active severe thunderstorms, that are expecting a direct impact typically within an hour. Severe thunderstorms can cause property damage and injury due to large hail, high winds, and flooding due to torrential rainfall. The exact criteria to issue a warning varies from country to country.
The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the purposes of protection, safety, and general information. It is a part of the National Oceanic and Atmospheric Administration (NOAA) branch of the Department of Commerce, and is headquartered in Silver Spring, Maryland, within the Washington metropolitan area. The agency was known as the United States Weather Bureau from 1890 until it adopted its current name in 1970.
The Storm Prediction Center (SPC) is a US government agency that is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the United States Department of Commerce (DoC).
Tropical cyclone warnings and watches are alerts issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local population and civil authorities to make appropriate preparation for the cyclone, including evacuation of vulnerable areas where necessary. It is important that interests throughout the area of an alert make preparations to protect life and property, and do not disregard it on the strength of the detailed forecast track.
A gale warning is an alert issued by national weather forecasting agencies around the world in an event that maritime locations currently or imminently experiencing winds of gale force on the Beaufort scale. Gale warnings allow mariners to take precautionary actions to ensure their safety at sea or to seek safe anchorage and ride out the storm on land. Though usually associated with deep low-pressure areas, winds strong enough to catalyze a gale warning can occur in other conditions too, including from anticyclones, or high-pressure systems, in the continental interior. The winds are not directly associated with a tropical cyclone.
This article describes severe weather terminology used by the National Weather Service (NWS) in the United States, a government agency operating within the Department of Commerce as an arm of the National Oceanic and Atmospheric Administration (NOAA).
The Edmonton tornado of 1987, an event also known as Black Friday to Edmontonians, was a powerful and devastating tornado that ripped through the eastern parts of Edmonton, Alberta, Canada and parts of neighbouring Strathcona County on the afternoon of Friday, July 31, 1987. It was one of seven other tornadoes in central Alberta the same day.
A red flag warning is a forecast warning issued by the National Weather Service (NWS) in the United States to inform the public, firefighters, and land management agencies that conditions are ideal for wildland fire combustion, and rapid spread. After drought conditions or a dry season, when humidity is very low, and especially when there are high or erratic winds, the Red Flag Warning becomes a critical statement for firefighting agencies. These agencies often alter their staffing and equipment resources dramatically to accommodate the forecast risk. To the public, a Red Flag Warning means high fire danger with increased probability of a quickly spreading vegetation fire in the area within 24 hours.
This article describes severe weather terminology used by the Meteorological Service of Canada, a branch within Environment and Climate Change Canada. The article primarily describes various weather warnings, and their criteria. Related weather scales and general weather terms are also addressed in this article. Some terms are specific to certain regions.
In weather forecasting in the United States, "particularly dangerous situation" (PDS) is enhanced wording used by the National Weather Service to convey special urgency in some watch or warning messages for unusually extreme and life-threatening severe weather events, above and beyond the average severity for the type of event. It is used in the format "This is a particularly dangerous situation..." at the discretion of the issuing forecaster. A watch or warning bearing the phrase is referred to as a PDS watch or PDS warning as shorthand jargon.
Severe weather is any dangerous meteorological phenomenon with the potential to cause damage, serious social disruption, or loss of human life. These vary depending on the latitude, altitude, topography, and atmospheric conditions. High winds, hail, excessive precipitation, and wildfires are forms and effects, as are thunderstorms, downbursts, tornadoes, waterspouts, tropical cyclones, and extratropical cyclones. Regional and seasonal phenomena include blizzards (snowstorms), ice storms, and duststorms.
A Special Weather Statement is a form of weather advisory. Special Weather Statements are issued by the National Weather Service of the United States (NWS) and the Meteorological Service of Canada (MSC). There are no set criteria for special weather statements in either country.
The National Severe Weather Warning Service is a service provided by the Met Office in the United Kingdom. The purpose of this service is to warn the public and emergency responders of severe or hazardous weather which has the potential to cause danger to life or widespread disruption. This allows emergency responders to put plans into place to help protect the public and also allowing the public to make necessary preparations.
A wind chill warning was a hazardous weather statement previously issued by both local forecast offices of the National Weather Service (NWS) in the United States and by the Meteorological Service of Environment and Climate Change Canada (ECCC) when wind chills were forecast to reach values low enough for residents and travelers to be susceptible to life-threatening medical conditions or death associated with accelerated body heat loss. In both Canada and the United States the "wind chill warning" has been replaced with the "extreme cold warning."
The 2019–20 South Pacific cyclone season was a slightly above-average season in which tropical cyclones formed within the South Pacific Ocean to the east of 160°E. The season officially ran from November 1, 2019, to April 30, 2020, however a tropical cyclone could form at any time between July 1, 2019, and June 30, 2020, and would count towards the season total. The season began on November 22 with the formation of Tropical Cyclone Rita, which would later become a severe tropical cyclone. The season has been near-average in terms of activity, with 8 tropical cyclones and 4 severe tropical cyclones forming during the season. The season featured Cyclone Harold, the first Category 5 severe tropical cyclone in the basin since Cyclone Gita, and one of the strongest since Cyclone Winston. During the season, tropical cyclones are officially monitored by the Fiji Meteorological Service (FMS), Australian Bureau of Meteorology (BOM) and New Zealand's MetService. The United States Armed Forces through the Joint Typhoon Warning Center (JTWC) also monitors the basin and issue unofficial warnings for American interests. The FMS attaches a number and an F suffix to tropical disturbances that form in or move into the basin while the JTWC designates significant tropical cyclones with a number and a P suffix. The FMS, BoM and MetService all use the Australian Tropical Cyclone Intensity Scale and estimate wind speeds over a period of ten minutes, while the JTWC estimated sustained winds over a 1-minute period, which are subsequently compared to the Saffir–Simpson hurricane wind scale (SSHWS).
National Weather Service - Norman, Oklahoma is a Weather Forecast Office (WFO) of the National Weather Service based in Norman, Oklahoma, which is responsible for forecasts and the dissemination of weather warnings and advisories for central and most of western Oklahoma, and western portions of north Texas. It is located in the National Weather Center on the University of Oklahoma campus, where it acts as one of the NOAA Weather Partners, a group of close-together weather-related agencies of the National Oceanic and Atmospheric Administration. NWS Norman is currently overseen by Mark Fox, who serves as the Meteorologist In Charge of the office.
The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.