|Formed||February 9, 1870|
|Jurisdiction||United States federal government|
|Headquarters|| Silver Spring, Maryland |
|Annual budget||US$1,124,149,000 (FY 2016)|
|Parent agency||National Oceanic and Atmospheric Administration|
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.
A government or state agency, sometimes an appointed commission, is a permanent or semi-permanent organization in the machinery of government that is responsible for the oversight and administration of specific functions, such as an intelligence agency. There is a notable variety of agency types. Although usage differs, a government agency is normally distinct both from a department or ministry, and other types of public body established by government. The functions of an agency are normally executive in character, since different types of organizations are most often constituted in an advisory role—this distinction is often blurred in practice however.
The Federal Government of the United States is the national government of the United States, a federal republic in North America, composed of 50 states, a federal district, five major self-governing territories, and several island possessions. The federal government is composed of three distinct branches: legislative, executive, and judicial, whose powers are vested by the U.S. Constitution in the Congress, the President, and the federal courts, respectively. The powers and duties of these branches are further defined by acts of congress, including the creation of executive departments and courts inferior to the Supreme Court.
The National Oceanic and Atmospheric Administration is an American scientific agency within the United States Department of Commerce that focuses on the conditions of the oceans, major waterways, and the atmosphere.
The NWS performs its primary task through a collection of national and regional centers, and 122 local Weather Forecast Offices (WFOs). As the NWS is an agency of the U.S. federal government, most of its products are in the public domain and available free of charge.
In 1870, the Weather Bureau of the United States was established through a joint resolution of Congress signed by President Ulysses S. Grantwith a mission to "provide for taking meteorological observations at the military stations in the interior of the continent and at other points in the States and Territories...and for giving notice on the northern (Great) Lakes and on the seacoast by magnetic telegraph and marine signals, of the approach and force of storms." The agency was placed under the Secretary of War as Congress felt "military discipline would probably secure the greatest promptness, regularity, and accuracy in the required observations." Within the Department of War, it was assigned to the U.S. Army Signal Service under Brigadier General Albert J. Myer. General Myer gave the National Weather Service its first name: The Division of Telegrams and Reports for the Benefit of Commerce.
In the United States Congress, a joint resolution is a legislative measure that requires passage by the Senate and the House of Representatives and is presented to the President for his approval or disapproval. Generally, there is no legal difference between a joint resolution and a bill. Both must be passed, in exactly the same form, by both chambers of Congress, and signed by the President to become a law. Only joint resolutions may be used to propose amendments to the United States Constitution and these do not require the approval of the President. Laws enacted by joint resolutions are not distinguished from laws enacted by bills, except that they are designated as resolutions as opposed to Acts of Congress.
The United States Congress is the bicameral legislature of the Federal Government of the United States. The legislature consists of two chambers: the House of Representatives and the Senate.
Ulysses S. Grant was an American soldier, politician, and international statesman, who served as the 18th president of the United States from 1869 to 1877. During the American Civil War Grant led the Union Army as its commanding general to victory over the Confederacy with the supervision of President Abraham Lincoln. During the Reconstruction Era, President Grant led the Republicans in their efforts to remove the vestiges of Confederate nationalism, racism, and slavery.
Cleveland Abbe – who began developing probabilistic forecasts using daily weather data sent by the Cincinnati Chamber of Commerce and Western Union, which he convinced to back the collection of such information in 1869 – was appointed as the Bureau's first chief meteorologist. In his earlier role as the civilian assistant to the chief of the Signal Service, Abbe urged the Department of War to research weather conditions to provide a scientific basis behind the forecasts; he would continue to urge the study of meteorology as a science after becoming Weather Bureau chief. While a debate went on between the Signal Service and Congress over whether the forecasting of weather conditions should be handled by civilian agencies or the Signal Service's existing forecast office, a Congressional committee was formed to oversee the matter, recommending that the office's operations be transferred to the Department of War following a two-year investigation.
Cleveland Abbe was an American meteorologist and advocate of time zones.
Cincinnati is a major city in the U.S. state of Ohio, and is the government seat of Hamilton County. Settled in 1788, the city is located at the northern side of the confluence of the Licking and Ohio rivers, the latter of which marks the state line with Kentucky. The city drives the Cincinnati–Middletown–Wilmington combined statistical area, which had a population of 2,172,191 in the 2010 census making it Ohio's largest metropolitan area. With a population of 296,943, Cincinnati is the third-largest city in Ohio and 65th in the United States. Its metropolitan area is the fastest growing economic power in the Midwestern United States based on increase of economic output and it is the 28th-largest metropolitan statistical area in the U.S. Cincinnati is also within a day's drive of 49.70% of the United States populace.
The Western Union Company is an American worldwide financial services and communications company. Its headquarters is in Meridian, Colorado, although the postal designation of nearby Englewood is used in its mailing address. Up until it discontinued the service in 2006, Western Union was globally the best-known American company in the business of exchanging telegrams.
The agency first became a civilian enterprise in 1890, when it became part of the Department of Agriculture. Under the oversight of that branch, the Bureau began issuing flood warnings and fire weather forecasts, and issued the first daily national surface weather maps; it also established a network to distribute warnings for tropical cyclones as well as a data exchange service that relayed European weather analysis to the Bureau and vice versa.The first Weather Bureau radiosonde was launched in Massachusetts in 1937, which prompted a switch from routine aircraft observation to radiosondes within two years. The Bureau prohibited the word "tornado" from being used in any of its weather products out of concern for inciting panic (a move contradicted in its intentions by the high death tolls in past tornado outbreaks due to the lack of advanced warning) until 1938, when it began disseminating tornado warnings exclusively to emergency management personnel.
The United States Department of Agriculture (USDA), also known as the Agriculture Department, is the U.S. federal executive department responsible for developing and executing federal laws related to farming, forestry, and food. It aims to meet the needs of farmers and ranchers, promote agricultural trade and production, work to assure food safety, protect natural resources, foster rural communities and end hunger in the United States and internationally.
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain. Depending on its location and strength, a tropical cyclone is referred to by different names, including hurricane, typhoon, tropical storm, cyclonic storm, tropical depression, and simply cyclone. A hurricane is a tropical cyclone that occurs in the Atlantic Ocean and northeastern Pacific Ocean, and a typhoon occurs in the northwestern Pacific Ocean; in the south Pacific or Indian Ocean, comparable storms are referred to simply as "tropical cyclones" or "severe cyclonic storms".
A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculate the following variables: altitude, pressure, temperature, relative humidity, wind, cosmic ray readings at high altitude and geographical position (latitude/longitude). Radiosondes measuring ozone concentration are known as ozonesondes.
The Bureau would later be moved to the Department of Commerce in 1940.On July 12, 1950, bureau chief Francis W. Reichelderfer officially lifted the agency's ban on public tornado alerts in a Circular Letter, noting to all first order stations that "Weather Bureau employees should avoid statements that can be interpreted as a negation of the Bureau's willingness or ability to make tornado forecasts", and that a "good probability of verification" exist when issuing such forecasts due to the difficulty in accurately predicting tornadic activity. However it would not be until it faced criticism for continuing to refuse to provide public tornado warnings and preventing the release of the USAF Severe Weather Warning Center's tornado forecasts (pioneered in 1948 by Air Force Capt. Robert C. Miller and Major Ernest Fawbush) beyond military personnel that the Bureau issued its first experimental public tornado forecasts in March 1952. In 1957, the Bureau began using radars for short-term forecasting of local storms and hydrological events, using modified versions of those used by Navy aircraft to create the WSR-57 (Weather Surveillance Radar, 1957), with a network of WSR systems being deployed nationwide through the early 1960s; some of the radars were upgraded to WSR-74 models beginning in 1974.
The United States Department of Commerce is the Cabinet department of the United States government concerned with promoting economic growth. Among its tasks are gathering economic and demographic data for business and government decision-making, and helping to set industrial standards. This organization's main purpose is to create jobs, promote economic growth, encourage sustainable development and improve standards of living for all Americans. The Department of Commerce headquarters is the Herbert C. Hoover Building in Washington, D.C.
Col. Robert C. Miller, USAF (1920–1998), was an American meteorologist, who pioneered severe convective storms forecasting and applied research, developing an empirical forecasting method, identifying many features associated with severe thunderstorms, a forecast checklist and manuals, and is known for the first official tornado forecast, and it verified, in 1948.
Radar is a detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna and a receiver and processor to determine properties of the object(s). Radio waves from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.
The Weather Bureau became part of the Environmental Science Services Administration when that agency was formed in August 1966. The Environmental Science Services Administration was renamed the National Oceanic and Atmospheric Administration (NOAA) on October 1, 1970, with the enactment of the National Environmental Policy Act. At this time, the Weather Bureau became the National Weather Service.NEXRAD (Next Generation Radar), a system of Doppler radars deployed to improve the detection and warning time of severe local storms, replaced the WSR-57 and WSR-74 systems between 1988 and 1997. Bob Glahn has written a comprehensive history of the first hundred years of the National Weather Service.
The NWS, through a variety of sub-organizations, issues different forecasts to users, including the general public. Although, throughout history, text forecasts have been the means of product dissemination, the NWS has been using more forecast products of a digital, gridded, image or other modern format.Each of the 122 Weather Forecast Offices (WFOs) send their graphical forecasts to a national server to be compiled in the National Digital Forecast Database (NDFD). The NDFD is a collection of common weather observations used by organizations and the public, including precipitation amount, temperature, and cloud cover among other parameters. In addition to viewing gridded weather data via the internet, users can download and use the individual grids using a "GRIB2 decoder" which can output data as shapefiles, netCDF, GrADS, float files, and comma separated variable files. Specific points in the digital database can be accessed using an XML SOAP service.
The National Weather Service issues many products relating to wildfires daily. For example, a Fire Weather Forecast, which have a forecast period covering up to seven days, is issued by local Weather Forecast Offices (WFOs) daily, with updates as needed. The forecasts contain weather information relevant to fire control and smoke management for the next 12 to 48 hours, such as wind direction and speed, and precipitation. The appropriate crews use this information to plan for staffing and equipment levels, the ability to conduct scheduled controlled burns, and assess the daily fire danger. Once per day, NWS meteorologists issue a coded fire weather forecast for specific United States Forest Service observation sites that are then input into the National Fire Danger Rating System (NFDRS). This computer model outputs the daily fire danger that is then conveyed to the public in one of five ratings: low, moderate, high, very high, or extreme.
The local Weather Forecast Offices of the NWS also, under a prescribed set of criteria, issue Fire Weather Watches and Red Flag Warnings as needed, in addition to issuing the daily fire weather forecasts for the local service area. These products alert the public and other agencies to conditions which create the potential for extreme fires. On the national level, the NWS Storm Prediction Center issues fire weather analyses for days one and two of the forecast period that provide supportive information to the local WFO forecasts regarding particular critical elements of fire weather conditions. These include large-scale areas that may experience critical fire weather conditions including the occurrence of "dry thunderstorms," which usually occur in the western U.S., and are not accompanied by any rain due to it evaporating before reaching the surface.
State and federal forestry officials sometimes request a forecast from a WFO for a specific location called a "spot forecast," which are used to determine whether it will be safe to ignite a prescribed burn and how to situate crews during the controlling phase. Officials send in a request, usually during the early morning, containing the position coordinates of the proposed burn, the ignition time, and other pertinent information. The WFO composes a short-term fire weather forecast for the location and sends it back to the officials, usually within an hour of receiving the request.
The NWS assists officials at the scene of large wildfires or other disasters, including HAZMAT incidents, by providing on-site support through Incident Meteorologists (IMET).IMETs are NWS forecasters specially trained to work with Incident Management Teams during severe wildfire outbreaks or other disasters requiring on-site weather support. IMETs travel quickly to the incident site and then assemble a mobile weather center capable of providing continuous meteorological support for the duration of the incident. The kit includes a cell phone, a laptop computer, and communications equipment, used for gathering and displaying weather data such as satellite imagery or numerical forecast model output. Remote weather stations are also used to gather specific data for the point of interest, and often receive direct support from the local WFO during such crises. IMETs, approximately 70 to 80 of which are employed nationally, can be deployed anywhere a disaster strikes and must be capable of working long hours for weeks at a time in remote locations under rough conditions.
The National Weather Service uses local branches, known as Weather Forecast Offices or WFOs, to issue products specific to those areas. Each WFO maintains a specific area of responsibility spanning multiple counties, parishes or other jurisdictions within the Continental United States – which, in some areas, cover multiple states – or individual possessions; the local offices handle responsibility of composing and disseminating forecasts and weather alerts to areas within their region of service. Some of the products that are only issued by the WFOs are severe thunderstorm and tornado warnings, flood, flash flood, and winter weather watches and warnings, some aviation products, and local forecast grids. The forecasts issued by a WFO are available on their individual pages within the Weather.gov website, which can be accessed through either forecast landing pages (which identify the office that disseminates the weather data) or via the alert map featured on the main page of the National Weather Service website.
The NWS supports the aviation community through the production of several forecasts. Each area's WFO has responsibility for the issuance of Terminal Aerodrome Forecasts (TAFs) for airports in their jurisdiction.TAFs are concise, coded 24-hour forecasts (30-hour forecasts for certain airports) for a specific airport, which are issued every six hours with amendments as needed. As opposed to a public weather forecast, a TAF only addresses weather elements critical to aviation; these include wind, visibility, cloud cover and wind shear.
Twenty-one NWS Center Weather Service Units (CWSU) are collocated with the Federal Aviation Administration (FAA) Air Route Traffic Control Centers (ARTCC). Their main responsibility is to provide up-to-the-minute weather information and briefings to the Traffic Management Units and control room supervisors. Special emphasis is given to weather conditions that could be hazardous to aviation or impede the flow of air traffic in the National Airspace System. Besides scheduled and unscheduled briefings for decision-makers in the ARTCC and other FAA facilities, CWSU meteorologists also issue two unscheduled products. The Center Weather Advisory (CWA) is an aviation weather warning for thunderstorms, icing, turbulence, and low cloud ceilings and visibilities. The Meteorological Impact Statement (MIS) is a two- to 12-hour forecast that outlines weather conditions expected to impact ARTCC operations.
The Aviation Weather Center (AWC), located in Kansas City, Missouri, is a central aviation support facility operated by the National Weather Service, which issues two primary products:
The Storm Prediction Center (SPC) in Norman, Oklahoma issues severe thunderstorm and tornado watches in cooperation with local WFOs which are responsible for delineating jurisdictions affected by the issued watch, and SPC also issues mesoscale discussions focused upon possible convective activity. SPC compiles reports of severe hail, wind, or tornadoes issued by local WFOs each day when thunderstorms producing such phenomena occur in a given area, and formats the data into text and graphical products. It also provides forecasts on convective activity through day eight of the forecast period (most prominently, the threat of severe thunderstorms, the risk of which is assessed through a tiered system conveyed among six categories – general thunderstorms, marginal, slight, enhanced, moderate, or high – based mainly on the expected number of storm reports and regional coverage of thunderstorm activity over a given forecast day), and is responsible for issuing fire weather outlooks, which support local WFOs in the determination of the need for Red Flag Warnings.
The Weather Prediction Center in College Park, Maryland provides guidance for future precipitation amounts and areas where excessive rainfall is likely,while local NWS offices are responsible for issuing Flood Watches, Flash Flood Watches, Flood Warnings, Flash Flood Warnings, and Flood Advisories for their local County Warning Area, as well as the official rainfall forecast for areas within their warning area of responsibility. These products can and do emphasize different hydrologic issues depending on geographic area, land use, time of year, as well as other meteorological and non-meteorological factors (for example, during the early spring or late winter a Flood Warning can be issued for an ice jam that occurs on a river, while in the summer a Flood Warning will most likely be issued for excessive rainfall).
In recent years, the NWS has enhanced its dissemination of hydrologic information through the Advanced Hydrologic Prediction Service (AHPS).The AHPS allows anyone to view near real-time observation and forecast data for rivers, lakes and streams. The service also enables the NWS to provide long-range probabilistic information which can be used for long-range planning decisions.
Daily river forecasts are issued by the thirteen River Forecast Centers (RFCs) using hydrologic models based on rainfall, soil characteristics, precipitation forecasts, and several other variables. The first such center was founded on September 23, 1946.Some RFCs, especially those in mountainous regions, also provide seasonal snow pack and peak flow forecasts. These forecasts are used by a wide range of users, including those in agriculture, hydroelectric dam operation, and water supply resources.
The National Weather Service Ocean Prediction Center (OPC) in College Park, Marylandissues marine products for areas that are within the national waters of the United States. NWS national centers or Weather Forecast Offices issue several marine products:
The National Hurricane Center (NHC) and the Central Pacific Hurricane Center (CPHC), respectively based in Miami, Florida and Honolulu, Hawaii, are responsible for monitoring tropical weather in the Atlantic, and central and eastern Pacific Oceans. In addition to releasing routine outlooks and discussions, the guidance center initiates advisories and discussions on individual tropical cyclones, as needed. If a tropical cyclone threatens the United States or its territories, individual WFOs begin issuing statements detailing the expected effects within their local area of responsibility. The NHC and CPHC issue products including tropical cyclone advisories, forecasts, and formation predictions, and warnings for the areas in the Atlantic and parts of the Pacific.
The Climate Prediction Center (CPC) in College Park, Maryland is responsible for all of the NWS's climate-related forecasts. Their mission is to "serve the public by assessing and forecasting the impacts of short-term climate variability, emphasizing enhanced risks of weather-related extreme events, for use in mitigating losses and maximizing economic gains." Their products cover time scales from a week to seasons, extending into the future as far as technically feasible, and cover the land, the ocean and the atmosphere, extending into the stratosphere. Most of the products issued by the center cover the Contiguous U.S. and Alaska.
Additionally, Weather Forecast Offices issue daily and monthly climate reports for official climate stations within their area of responsibility. These generally include recorded highs, lows and other information (including historical temperature extremes, fifty-year temperature and precipitation averages, and degree days). This information is considered preliminary until certified by the National Climatic Data Center.
The primary network of surface weather observation stations in the United States is composed of Automated Surface Observing Systems (ASOS). The ASOS program is a joint effort of the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DOD).ASOS stations are designed to support weather forecast activities and aviation operations and, at the same time, support the needs of the meteorological, hydrological, and climatological research communities. ASOS was especially designed for the safety of the aviation community, therefore the sites are almost always located near airport runways. The system transmits routine hourly observations along with special observations when conditions exceed aviation weather thresholds (e.g. conditions change from visual meteorological conditions to instrument meteorological conditions). The basic weather elements observed are: sky condition, visibility, present weather, obstructions to vision, pressure, temperature, dew point, wind direction and speed, precipitation accumulation, and selected significant remarks. The coded observations are issued as METARs and look similar to this:
METAR KNXX 121155Z 03018G29KT 1/4SM +TSSN FG VV002 M05/M07 A2957 RMK PK WND 01029/1143 SLP026 SNINCR 2/10 RCRNR T2 SET 6///// 7//// 4/010 T10561067 11022 21056 55001 PWINO PNO FZRANO
Getting more information on the atmosphere, more frequently, and from more locations is the key to improving forecasts and warnings. Due to the large installation and operating costs associated with ASOS, the stations are widely spaced. Therefore, the Cooperative Observer Program (COOP), a network of approximately 11,000 mostly volunteer weather observers, provides much of the meteorological and climatological data to the country. The program, which was established in 1890 under the Organic Act, currently has a twofold mission:
The National Weather Service also maintains connections with privately operated mesonets such as the Citizen Weather Observer Program for data collection, in part, through the Meteorological Assimilated Data Ingest System (MADIS). Funding is also provided to the CoCoRaHS volunteer weather observer network through parent agency NOAA.
NWS forecasters need frequent, high-quality marine observations to examine conditions for forecast preparation and to verify their forecasts after they are produced. These observations are especially critical to the output of numerical weather models because large bodies of water have a profound impact on the weather. Other users rely on the observations and forecasts for commercial and recreational activities. To help meet these needs, the NWS's National Data Buoy Center (NDBC) in Hancock County, Mississippi operates a network of about 90 buoys and 60 land-based coastal observing systems (C-MAN). The stations measure wind speed, direction, and gust; barometric pressure; and air temperature. In addition, all buoy and some C-MAN stations measure sea surface temperature, and wave height and period.Conductivity and water current are measured at selected stations. All stations report on an hourly basis.
Supplemental weather observations are acquired through the United States Voluntary Observing Ship (VOS) program.It is organized for the purpose of obtaining weather and oceanographic observations from transiting ships. An international program under World Meteorological Organization (WMO) marine auspices, the VOS has 49 countries as participants. The United States program is the largest in the world, with nearly 1,000 vessels. Observations are taken by deck officers, coded in a special format known as the "ships synoptic code", and transmitted in real-time to the NWS. They are then distributed on national and international circuits for use by meteorologists in weather forecasting, by oceanographers, ship routing services, fishermen, and many others. The observations are then forwarded for use by the National Climatic Data Center (NCDC) in Asheville, North Carolina.
Upper air weather data is essential for weather forecasting and research. The NWS operates 92 radiosonde locations in North America and ten sites in the Caribbean. A small, expendable instrument package is suspended below a 2 metres (6.6 ft) wide balloon filled with hydrogen or helium, then released daily at or shortly after 1100 and 2300 UTC, respectively. As the radiosonde rises at about 300 meters/minute (1,000 ft/min), sensors on the radiosonde measure profiles of pressure, temperature, and relative humidity. These sensors are linked to a battery-powered radio transmitter that sends the sensor measurements to a ground receiver. By tracking the position of the radiosonde in flight, information on wind speed and direction aloft is also obtained. The flight can last longer than two hours, and during this time the radiosonde can ascend above 35 km (115,000 ft) and drift more than 200 km (120 mi) from the release point. When the balloon has expanded beyond its elastic limit and bursts (about 6 m or 20 ft in diameter), a small parachute slows the descent of the radiosonde, minimizing the danger to lives and property. Data obtained during the flights is coded and disseminated, at which point it can be plotted on a Skew-T or Stuve diagram for analysis. In recent years, the National Weather Service has begun incorporating data from AMDAR in its numerical models (however, the raw data is not available to the public).
The National Weather Service has developed a multi-tier concept for forecasting or alerting the public to all types of hazardous weather:
Short-fused weather warnings and advisories issued by local NWS forecast offices are generally less than 500–5,000 square miles (1,300–12,900 km2) in area. Warnings for severe local storms are intended to be issued preceding the arrival of severe weather at a particular locale by one hour or less; the NWS also issues warnings and advisories for various hydrological and non-hydrological events including floods, non-thunderstorm high winds, winter storms, intense heat or cold, fire weather and marine hazards, which vary in timepsan depending on the weather situation (inland and coastal warnings for tropical cyclones are issued by the National Hurricane Center (NHC), a guidance center of the National Oceanic and Atmospheric Administration). The NWS defines a warning as a "hazardous weather or hydrologic event [that] is occurring, is imminent, or has a very high probability of occurring" and an advisory as "[highlighting] special weather conditions that are less serious than a warning [...] for events that may cause significant inconvenience, and if caution is not exercised, [..] could lead to situations that may threaten life and/or property." In earnest, they indicate that hazardous weather conditions are occurring that may pose a risk to life and property, and are intended to direct the general public to take immediate action and heed safety precautions; it also has the side purpose of directing emergency management personnel to be on standby in case the weather situation leads to property damage or casualties. Severe thunderstorm and flood warnings indicate that organized severe thunderstorms or flooding are occurring, whereas tornado warnings are issued if a storm is indicated to be producing an observed tornado or exhibits strong, low-level rotation.
The process of issuing a warning or advisory begins with observations of a hydrological or extreme weather event that is either occurring at present (through radar imagery, reports from local television and radio stations, or ground observations by local law enforcement, civil defense officials, media outlets or storm spotters) or is forecast to occur within 12 to 24 hours. If after collaboration a warning or advisory is deemed necessary, the Weather Forecast Office will generate a bulletin product via the Advance Weather Interactive Processing System (AWIPS) and then disseminate the alert through various communication routes accessed by the media and various agencies, on the internet, to NOAA satellites, and on NOAA Weather Radio.
The product outlines the alert type, the issuing WFO, the sections of government subdivisions (county, parish or boroughs) covered by the alert, and its time of expiration (based on the local time zone). Some products – particularly for severe thunderstorm, tornado and flood warnings – include a tag requesting Emergency Alert System activation to trigger public alert messages via television, radio stations, NOAA Weather Radio, and smartphone apps and messaging services. For local storm events, the warning or advisory product also outlines a meteorological summary of the most recent storm location or local storm report issued prior to the product's issuance (including the approximate area in statute miles and estimated speed and direction), associated hazards, impacts, municipalities and designated land areas (and, if applicable, highway mile markers) covered by the alert, and boilerplate action messages informing the public of safety precautions they need to take or advising them to be vigilant of any warnings or weather statements that may be issued by their local National Weather Service office. A statement may be issued as a follow-up message to a warning, watch, or emergency, which may update, extend, or cancel the previously issued product or be used as a notification of significant weather for which no type of alert is currently in effect for a given location or is expected to be in effect.
In situations where a forecaster indicates a significant threat of extremely severe and life-threatening weather with an ongoing local weather event, enhanced wording may be used to note the heightened threat by a significant local storm event. In April 2012, the NWS introduced the Impact Based Warning system at its Weather Forecast Offices in Wichita and Topeka, Kansas, and Springfield, St. Louis and Kansas City/Pleasant Hill, Missouri; the pilot project – which would expand to 80 Weather Forecast Offices overseen by the Central, Eastern, Southern and Western Region Headquarters by the spring of 2015 – incorporate message tags within the main body of the product describing the source of the hazard report, damage potential, and if applicable, radar indications or physical observations of tornadoes or the possibility of a tornado; hazards are also summarized at the close of the product text (describing estimated maximum hail size and wind gusts, and if applicable, if a storm has the potential to produce a tornado or in the event of a tornado warning, the basis of the warning or its damage threat).The wording "Particularly Dangerous Situation" (PDS), which originated by the Storm Prediction Center for use in tornado watch products during expected high-end severe weather outbreaks, is subjectively issued. It is occasionally issued with tornado warnings, normally if a large tornado capable of producing EF3 to EF5 damage or staying on the ground for long-duration – sometimes uninterrupted – paths has been reported (although a tornado emergency may be issued in such cases if the tornado is expected to track into a densely populated area). PDS warnings for other alerts occur with even less frequency, and their criteria varies depending on the alert type to which the wording is applied.
Until September 30, 2007, local offices of the National Weather Service issued warnings for severe thunderstorms, tornadoes, flash flooding and marine hazards using geopolitical boundaries. The implementation of storm-based warnings on October 1, 2007, saw alerts for these meteorological or hydrological threats be delineated by polygonal shapes in map-based weather hazard products, which outline the specified sections of government sub-jurisdictions that the warning covers, based on the projected path of a storm as determined by Doppler radar at the time of the warning's issuance; however, entire counties/parishes may sometimes be included in the warning polygon, especially if they encompass a small geographical area.Warnings can be expanded, contracted (by removing jurisdictions where SPC and NWS forecasters no longer consider there to be a viable threat of severe weather, in which case, the storm-based warning may take on a trapezoidal representation in map-based watch products) or canceled before their set time of expiration by local NWS offices.
The NWS also releases Experimental Severe Weather Impact products for use on social media accounts maintained by local forecast offices as well as the Enhanced Data Display (EDD), an experimental pilot project created by the Charleston, West Virginia office's WeatherReady Nation initiative. The product provides a graphical depiction of short-fuse warnings and watches (specifically, tornado and severe thunderstorm watches and warnings, and flash flood warnings), showing a map of the warning area (outlined as a red polygon) and locations (including communities and interstate highways) that will be impacted. For severe thunderstorm, tornado and flash flood warnings, the estimated population count of the warned area and approximate totals of public schools and hospitals within the warning area as well as the maximum forecast intensity of hail size, wind gusts and potential tornadoes; tornado warnings referenced in the impact product also denote whether the warning was issued based on radar indication or ground confirmation.
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NOAA Weather Radio All Hazards (NWR), promoted as "The Voice of the National Weather Service", is a special radio system that transmits uninterrupted weather watches, warnings and forecasts 24 hours a day directly from a nearby NWS office, with the broadcasts covering across 95–97% of the United States' population. The system – which is owned and operated by the NWS – consists of 1,030 transmitters, covering all 50 states; adjacent coastal waters; Puerto Rico; the U.S. Virgin Islands; and the U.S. Pacific Territories of American Samoa, Guam and the Northern Mariana Islands. NWR requires a scanner or special radio receiver capable of picking up the signal. Individual NWR stations broadcast any one of seven allocated frequencies centered on 162 MHz (known collectively as "weather band") in the marine VHF radio band. In recent years, national emergency response agencies such as the Federal Emergency Management Agency (FEMA) and the Department of Homeland Security have begun to take advantage of NWR's ability to efficiently reach a large portion of the U.S. population. When necessary, the system can also be used (in conjunction with the Emergency Alert System) to broadcast civil, natural and technological emergency and disaster alerts and information, in addition to those related to weather – hence the addition of the phrasing "All Hazards" to the name.
The NOAA Weather Wire Service (NWWS) is a satellite data collection and dissemination system operated by the National Weather Service, which was established in October 2000. Its purpose is to provide state and federal government, commercial users, media and private citizens with timely delivery of meteorological, hydrological, climatological and geophysical information. All products in the NWWS data stream are prioritized, with weather and hydrologic warnings receiving the highest priority (watches are next in priority). NWWS delivers severe weather and storm warnings to users in ten seconds or less from the time of their issuance, making it the fastest delivery system available. Products are broadcast to users via the AMC-4 satellite.
The Emergency Managers Weather Information Network (EMWIN) is a system designed to provide the emergency management community with access to a set of NWS warnings, watches, forecasts and other products at no recurring cost. It can receive data via radio, internet, or a dedicated satellite dish, depending on the needs and capabilities of the user.
NOAAPORT is a one-way broadcast communication system which provides NOAA environmental data and information in near real-time to NOAA and external users. This broadcast service is implemented by a commercial provider of satellite communications utilizing C band.
The agency's online service, Weather.gov, is a data rich website operated by the NWS that serves as a portal to hundreds of thousands of webpages and more than 300 different NWS websites. Through its homepage, users can access local forecasts by entering a place name in the main forecast search bar, view a rapidly updated map of active watches and warnings, and select areas related to graphical forecasts, national maps, radar displays, river and air quality data, satellite images and climate information. Also offered are XML data feeds of active watches and warnings, ASOS observations and digital forecasts for 5x5 kilometer grids. All of NWS local weather forecast offices operate their own region-tailored web pages, which provide access to current products and other information specific to the office's local area of responsibility. Weather.gov superseded the Interactive Weather Information Network (IWIN), the agency's early internet service which provided NWS data from the 1990s through the mid-2000s.
Since 1983, the NWS has provided external user access to weather information obtained by or derived from the U.S. Government through a collection of data communication line services called the Family of Services (FOS), which is accessible via dedicated telecommunications access lines in the Washington, D.C., area. All FOS data services are driven by the NWS Telecommunication Gateway computer systems located at NWS headquarters in Silver Spring, Maryland. Users may obtain any of the individual services from NWS for a one-time connection charge and an annual user fee.
The WSR-88D Doppler weather radar system, also called NEXRAD, was developed by the National Weather Service during the mid-1980s, and fully deployed throughout the majority of the United States by 1997. There are 158 such radar sites in operation in the U.S., its various territorial possessions and selected overseas locations. This technology, because of its high resolution and ability to detect intra-cloud motions, is now the cornerstone of the agency's severe weather warning operations.
National Weather Service meteorologists use an advanced information processing, display and telecommunications system, the Advance Weather Interactive Processing System (AWIPS), to complete their work. These workstations allow them to easily view a multitude of weather and hydrologic information, as well as compose and disseminate products. The NWS Environmental Modeling Center was one of the early users of the ESMF common modeling infrastructure. The Global Forecast System (GFS) is one of the applications that is built on the framework.
In 2016, the NWS significantly increased the computational power of its supercomputers, spending $44 million on two new supercomputers from Cray and IBM. This was driven by relatively lower accuracy of NWS' Global Forecast System (GFS) numerical weather prediction model, compared to other global weather models.This was most notable in the GFS model incorrectly predicting Hurricane Sandy turning out to sea until four days before landfall; while the European Centre for Medium-Range Weather Forecasts' model predicted landfall correctly at seven days. The new supercomputers increased computational processing power from 776 teraflops to 5.78 petaflops.
Critics such as University of Washington professor Cliff Masshave pointed out that NWS forecasts are not as accurate as they could be, and that this has resulted in inaccurate daily weather forecasts and dangerously bad predictions concerning the location and intensity of extreme weather events like blizzards and hurricanes. Certain private companies, the British Met Office, the European Centre for Medium-Range Weather Forecasts (ECMWF), and the Northwest Regional Modeling Consortium in Seattle have been cited as producing more accurate predictions in certain circumstances. According to critics, causes include:
The Next Generation Global Prediction System project at NWS aims to address some of these criticisms by running a unified high-quality model that takes advantage of more recent research results.
While respected as one of the premier weather organizations in the world, the National Weather Service has been perceived by some conservatives as competing unfairly with the private sector.National Weather Service forecasts and data, being works of the federal government, are in the public domain and thus available to anyone for free in accordance with United States law. From time to time, the situation receives official review to ascertain if a leaner, more efficient approach may be had by some degree of privatization.
In 1983, under the administration of President Ronald Reagan, NOAA administrator John V. Byrne announced a proposal to sell all of the agency's weather satellites at auction with the intent to repurchase the weather data from private contractors that would acquire the satellites. Under the proposal, 30% of NOAA's workforce would be reviewed for potential layoffs, and certain specialty forecasts of agricultural and economic importance would be eliminated. NOAA also proposed outsourcing of weather observation stations, NOAA Weather Radio and computerized surface analysis to private companies. The proposal was met with negative reaction among the public, members of Congress and consumer advocacy groups (including most notably, Ralph Nader), objecting to the possibility of weather information intended for the public domain being sold to private entities that would profit from the sale of the data. The proposal to sell the satellite network failed in a Congressional vote, while other aspects of the proposal to dismantle portions of NOAA's agencies were eventually scuttled.
In 2005, Pennsylvania Senator Rick Santorum introduced the National Weather Service Duties Act of 2005,a bill which would have prohibited the NWS from freely distributing weather data. The bill was widely criticized by users of the NWS's services, especially by emergency management officials who rely on the National Weather Service for information during situations such as fires, flooding, or severe weather. Groups such as the Aircraft Owners and Pilots Association condemned the bill's restrictions on weather forecasting as threatening the safety of air traffic, noting that 40% of all aviation accidents are at least partially weather-related. The bill attracted no cosponsors, and died in committee during the 2005 Congressional session.
Skywarn is a program of the United States' National Weather Service (NWS). Its mission is to collect reports of localized severe weather. These reports are used to aid forecasters in issuing and verifying severe weather watches and warnings and to improve the forecasting and warning processes and the tools used to collect meteorological data. Reports are also used by local emergency managers and public safety officials.
A tornado warning is an alert issued by national weather forecasting agencies to warn the public that severe thunderstorms with tornadoes are imminent or occurring. It can be issued after a tornado, funnel cloud and rotation in the clouds has been spotted by the public, storm chasers, emergency management or law enforcement.
A tornado watch is issued when weather conditions are favorable for the development of severe thunderstorms called a supercell that are capable of producing tornadoes. A tornado watch therefore implies that it is also a severe thunderstorm watch. A tornado watch must not be confused with a tornado warning. In most cases, the potential exists for large hail and/or damaging winds in addition to tornadoes.
A Severe Thunderstorm Watch is issued when weather conditions are favorable for the development of severe thunderstorms. If thunderstorms are expected to be of sufficient strength such that there is a significant risk that they may produce tornadoes, then a Tornado Watch is issued. A Severe Thunderstorm Watch can also be upgraded to a Tornado Watch if conditions originally forecasted for limited to no tornadic development change to allow possible tornado formation. A watch must not be confused with a Severe Thunderstorm Warning.
A severe thunderstorm warning is issued by the National Weather Service when trained storm spotters or Doppler weather radar indicate that a thunderstorm is producing or will soon produce dangerously large hail or high winds, capable of causing significant damage. In the United States, severe thunderstorm warnings do not account for lightning, a significant hazard in any thunderstorm, or flooding caused by a thunderstorm's extreme rainfall. A similar warning is issued by Environment Canada's Meteorological Service of Canada from their offices in Vancouver, Edmonton, Toronto, Montreal and Dartmouth. Skywarn issues the severe thunderstorm warnings for the United Kingdom. Just as in the United States, lightning does not warrant a severe thunderstorm warning. In Australia, severe thunderstorm warnings are issued by the Bureau of Meteorology for all Australian states.
NOAA Weather Radio is an automated 24-hour network of VHF FM weather radio stations in the United States that broadcast weather information directly from a nearby National Weather Service office. The routine programming cycle includes local or regional weather forecasts, synopsis, climate summaries, synopsis or zone/lake/coastal waters forecasts. During severe conditions the cycle is shortened into: hazardous weather outlooks, short-term forecasts, special weather statements or tropical weather summaries. It occasionally broadcasts other non-weather related events such as national security statements, natural disaster information, environmental and public safety statements sourced from the Federal Communications Commission's (FCC) Emergency Alert System. NOAA Weather Radio uses automated broadcast technology that allows for the recycling of segments featured in one broadcast cycle seamlessly into another and more regular updating of segments to each of the transmitters. It also speeds up the warning transmitting process.
The Storm Prediction Center (SPC) is a 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).
The Advanced Weather Interactive Processing System (AWIPS) is a technologically advanced processing, display, and telecommunications system that is the cornerstone of the United States National Weather Service's (NWS) operations.
The United States National Centers for Environmental Prediction (NCEP) delivers national and global weather, water, climate and space weather guidance, forecasts, warnings and analyses to its Partners and External User Communities. These products and services are based on a service-science legacy and respond to user needs to protect life and property, enhance that nation's economy and support the nation's growing need for environmental information. The centers form part of the National Weather Service.
The National Severe Storms Laboratory (NSSL) is a National Oceanic and Atmospheric Administration (NOAA) weather research laboratory under the Office of Oceanic and Atmospheric Research. It is one of seven NOAA Research Laboratories (RLs).
This article describes severe weather terminology used by the National Weather Service (NWS) in the United States. The NWS, a government agency operating as an arm of the National Oceanic and Atmospheric Administration (NOAA) branch of the United States Department of Commerce (DoC), defines precise meanings for nearly all of its weather terms. This article describes NWS terminology and related weather scales used by the agency. Some terms may be specific to certain cities or regions.
First Warning is the name of a severe weather warning system designed for broadcast television stations, typically those in the United States. A weather advisory product based on First Warning, called First Alert, is an automated version of this product, which has come into widespread use by television stations and is marketed under different names depending on the graphics service vendor.
The tornado outbreak of January 1–2, 2006, was one of the largest tornado outbreaks ever recorded in the month of January behind the January 2008 tornado outbreak sequence the January 12–13, 2006, tornadoes, the January 17–18, 1999 tornado outbreak, the January 21-23, 2017 tornado outbreak, and the January 21–23, 1999 tornado outbreak. The outbreak affected much of the Central and Southern United States and produced 20 tornadoes. The tornadoes caused considerable damage in the states of Kentucky and Georgia. There were no tornado related fatalities and only minor injuries were reported.
A Particularly Dangerous Situation (PDS) is a type of enhanced wording first used by the Storm Prediction Center (SPC), a national guidance center of the United States National Weather Service, for tornado watches and eventually expanded to use for other severe weather watches and warnings. It is issued at the discretion of the forecaster composing the watch or warning and implies that there is an enhanced risk of very severe and life-threatening weather, usually a major tornado outbreak or a long-lived, extreme derecho event, but possibly another weather hazard such as an exceptional flash flood or fire.
A Local Storm Report (LSR) is transmitted by the National Weather Service (NWS) when it receives significant information from storm spotters, such as amateur radio operators, storm chasers, law enforcement officials, civil defense personnel, firefighters, EMTs or public citizens, about severe weather conditions in their warning responsibility area. Those reports are received by local National Weather Service offices (WFOs), and they can be used to issue Severe Thunderstorm Warnings, Tornado Warnings, and other weather warnings/bulletins, in addition to the LSR.
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.
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 David Andra, who serves as the Meteorologist In Charge of the office.
The National Weather Service Boston/Norton, Massachusetts is a local office of the National Weather Service (NWS), run under the auspices of the NWS' Eastern Region. This Weather Forecast Office (WFO) is responsible for monitoring weather conditions throughout most of Southern New England. The Southern New England Weather Forecast Office provides warning and forecast services for most of Massachusetts, Northern Connecticut, all of Rhode Island, and Cheshire and Hillsborough counties in Southern New Hampshire. However, Cheshire and Hillsborough counties in New Hampshire was transferred to the NWS WFO in Gray, Maine effective on December 3, 2014 at 8 AM EST. Besides public weather services, WFO Norton (BOX) provides marine, aviation, fire weather, and hydrological forecast services. Additional hydrologic information is provided by the co-located Northeast River Forecast Center (NERFC).
National Weather Service - Pleasant Hill/Kansas City, Missouri is a Weather Forecast Office (WFO) of the National Weather Service, which is responsible for forecasts and the dissemination of weather warnings and advisories for 37 counties in northern and western Missouri and seven counties in extreme eastern Kansas, including the Kansas City and St. Joseph metropolitan areas. Though, as the Storm Prediction Center (SPC) in Norman, Oklahoma is responsible for issuing severe thunderstorm and tornado watches, the Pleasant Hill/Kansas City WFO only composes outline and status updates for SPC-issued watches affecting any portion of its designated County Warning Area.
The National Weather Service Fort Worth, Texas is a local weather forecast office of the National Weather Service responsible for monitoring weather conditions for 46 counties in north central Texas, including the Dallas-Fort Worth Metro Area and Waco, Texas.
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