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94-453: NSSL studies weather radar, tornadoes, flash floods, lightning, damaging winds, hail, and winter weather out of Norman, Oklahoma, using various techniques and tools in their HWT, or Hazardous Weather Testbed. NSSL meteorologists developed the first doppler radar for the purpose of meteorological observation, and contributed to the development of the NEXRAD (WSR-88D). NSSL has a partnership with

188-710: A severe weather event. Where possible, they were co-located with NWS Weather Forecast Offices (WFOs) to permit quicker access by maintenance technicians. The NEXRAD radars incorporated a number of improvements over the radar systems that were previously in use. The new system provided Doppler velocity, improving tornado prediction ability by detecting rotation present within the storm at different scan angles. It provided improved resolution and sensitivity, enabling operators to see features such as cold fronts , thunderstorm gust fronts , and mesoscale to even storm scale features of thunderstorms that had never been visible on radar. The NEXRAD radars also provided volumetric scans of

282-412: A 4 km resolution of precipitation, lightning threat, and more. WoF Tornado Threat Prediction (WoF-TTP) is a research project to develop a 0–1 hour, 1-km resolution suite of high detail computer models to forecast individual convective storms and their tornadic potential. Target future average lead-time for tornado warnings via WoF-TTP is 40–60 minutes. The technology and science developed to achieve

376-430: A Doppler lidar, a multi-channel microwave radiometer, and an Atmospheric Emitted Radiance Interferometer (AERI). CLAMPS meets a NOAA/NWS operational and research need of for profiles of temperature, humidity, and winds near the surface of the earth. NSSL's Field Observing Facilities and Support group (FOFS) is responsible for a device called an Electric Field Meter (EFM) that is attached, along with other instruments, to

470-478: A Parsivel (PARticle, SIze, VELocity) disdrometer. These can be deployed quickly in the field, in and around thunderstorms. NSSL launches special research weather balloon systems into thunderstorms. Measurements from the sensor packages attached to the balloons provide data about conditions inside the storm where it has often proved too dangerous for research aircraft to fly. PASIV is a balloon-borne instrument designed to capture images of water and ice particles as it

564-586: A combination of University of Oklahoma, NOAA and state organizations that work in collaboration. In 1962 a research team from the United States Weather Bureau's National Severe Storms Project (NSSP) moved from Kansas City, Missouri to Norman, Oklahoma , where, in 1956, the Cornell Aeronautical Laboratory had installed a 3 cm continuous-wave Doppler Weather Surveillance Radar-1957 ( WSR-57 ). This radar

658-516: A combination of observing systems ranging from radars to satellites on a national scale to produce precipitation forecasts. NMQ's prototype QPE products are also known as “Q2” - next-generation products combining the most effective multi-sensor techniques to estimate precipitation. NSSL scientists helped develop the Weather Surveillance Radar - 1988 Doppler (WSR-88D) radars, also known as NEXt-generation RADar (NEXRAD) . Since

752-489: A developing thunderstorm. They are also working on products that estimate wind shear and stability in the surrounding environment to forecast the future severity of the storm. NSSL uses special instruments mounted on the top of the National Weather Center that can measure the thermodynamic properties of the lowest 1–2 km of the atmosphere (boundary layer). Researchers study the data to learn more about

846-437: A false sense of security that a tornado was farther away from them than it really was, endangering residents in the storm's path. The Supplemental Adaptive Intra-Volume Low-Level Scan (SAILS) technique, deployed with Build 14 in the first half of 2014, allows operators the option to run an additional base scan during the middle of a typical volume scan. With one SAILS cut active on VCP 212, base scans occur about once every two and

940-557: A half minutes, with more frequent updates if AVSET terminates the volume scan early. Multiple Elevation Scan Option for Supplemental Adaptive Intra-Volume Low-Level Scan (MESO-SAILS) is an enhancement to SAILS, which allows the radar operator to run one, two or three additional base scans during the course of a volume scan, per the operators request. During June 2013, the Radar Operations Center first tested SAILSx2, which adds two additional low-level scans per volume. It

1034-736: A known coverage gap was filled when the Langley Hill radar in southwestern Washington was installed, using the last remaining spare. This radar opportunity was spearheaded by a public campaign led by Professor Cliff Mass at the University of Washington, and likely helped the NWS office in Portland, Oregon issue a timely warning for the Manzanita, OR EF-2 tornado in October, 2016. In 2021,

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1128-490: A list of upcoming improvements to the WSR-88D system. Beyond dual-polarization, the advent of phased array radar will probably be the next major improvement in severe weather detection. Its ability to rapidly scan large areas would give an enormous advantage to radar meteorologists. Its additional ability to track both known and unknown aircraft in three dimensions would allow a phased array network to simultaneously replace

1222-500: A phenomenon known as "The Cone of Silence" is present with all NEXRAD radars. The term describes the lack of coverage directly above the radar sites. There are currently seven Volume Coverage Patterns (VCP) available to NWS meteorologists, with an eighth in the process of replacing one of the existing seven. Each VCP is a predefined set of instructions that control antenna rotation speed, elevation angle, transmitter pulse repetition frequency and pulse width. The radar operator chooses from

1316-471: A range of 230 km (140 mi). Super Resolution provides reflectivity data with a sample size of 0.25 km (0.16 mi) by 0.5 degree, and increase the range of Doppler velocity data to 300 km (190 mi). Initially, the increased resolution is only available in the lower scan elevations. Super resolution makes a compromise of slightly decreased noise reduction for a large gain in resolution. The improvement in azimuthal resolution increases

1410-560: A rapid basis to collect data or coordinate field operations. NSSL researchers with the University of Oklahoma built their first mobile Doppler weather radar in 1993. Current versions of mobile radars (for example, NSSL's NOXP) can be driven into positions very close to storms, observing details that are typically out of sight of the beam of more distant WSR-88D radars. NSSL has also used mobile radars to study tornadoes, hurricanes, dust storms, winter storms, mountain rainfall, and even biological phenomena. NSSL installed, operates and maintains

1504-477: A result, in many cases when severe weather was farther from the radar site, forecasters could not provide as timely severe weather warnings as possible. The Automated Volume Scan Evaluation and Termination (AVSET) algorithm helps solve this problem by immediately ending the volume scan when precipitation returns at higher scan angles drop below a set threshold (around 20 dBZ). This can often allow for more volume scans per hour, improving severe weather detection without

1598-630: A rich dataset with a diverse range of applications, including severe weather diagnosis and climatological information. NOAA's Hazardous Weather Testbed (HWT) is jointly managed by NSSL, the Storm Prediction Center (SPC) and the National Weather Service Oklahoma City/Norman Weather Forecast Office (OUN) on the University of Oklahoma campus inside the National Weather Center. The HWT is designed to accelerate

1692-584: A special research balloon and launched into thunderstorms. As they are carried up through electrified storms, these EFMs are designed to measure the strength and direction of the electric fields that build up before lightning strikes occur. Data from this instrument helps researchers learn more about the electrical structure of storms. NSSL operates two mobile laboratories (custom built by an ambulance company) called NSSL6 and NSSL7, outfitted with computer and communication systems, balloon launching equipment, and weather instruments. These mobile labs can be deployed on

1786-622: A truck. The mobile radar can be driven into position as a storm is developing to scan the atmosphere at low levels, below the beam of WSR-88D radars. NSSL has used mobile radars to study tornadoes, hurricanes, dust storms, winter storms, mountain rainfall, and even biological phenomena. Forecasting a Continuum of Environmental Threats (FACETs) serves as a broad-based framework and strategy to help focus and direct efforts related to next-generation science, technology and tools for forecasting environmental hazards. FACETs will address grid-based probabilistic threats, storm-scale observations and guidance,

1880-529: A volume up to 4 times, depending on the operators choice. The angles are as follows, alongside their respective scan frequencies: The operator can not use MESO-SAILS alongside MRLE simultaneously. If one is selected while the other is active, the NEXRAD algorithms will automatically set the other "off". Started on March 13, 2013, the SLEP, or Service Life Extension Program, is an extensive effort to keep and maintain

1974-407: Is WSR-88D ( Weather Surveillance Radar, 1988, Doppler ). NEXRAD detects precipitation and atmospheric movement or wind . It returns data which when processed can be displayed in a mosaic map which shows patterns of precipitation and its movement. The radar system operates in two basic modes, selectable by the operator – a slow-scanning clear-air mode for analyzing air movements when there

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2068-495: Is freely available to users outside of the NWS, including researchers , media , and private citizens . The primary goal of NEXRAD data is to aid NWS meteorologists in operational forecasting . The data allows them to accurately track precipitation and anticipate its development and track. More importantly, it allows the meteorologists to track and anticipate severe weather and tornadoes. Combined with ground reports, tornado and severe thunderstorm warnings can be issued to alert

2162-775: Is a network of 159 high-resolution S-band Doppler weather radars operated by the National Weather Service (NWS), an agency of the National Oceanic and Atmospheric Administration (NOAA) within the United States Department of Commerce , the Federal Aviation Administration (FAA) within the Department of Transportation , and the U.S. Air Force within the Department of Defense . Its technical name

2256-406: Is investigating to see if both the aircraft surveillance and weather surveillance functions can be combined into one radar. Combining the operational capabilities of these various radar systems into a single radar unit would result in fiscal savings and consume fewer resources. NSSL researchers teamed up with several universities to build a mobile Doppler radar: a Doppler radar mounted on the back of

2350-431: Is launched into, and rises up through, a thunderstorm. The instrument is flown as part of a “train” of other instruments connected one after another to a balloon. These other instruments measure electrical field strength and direction, and other variables such as temperature, dewpoint, pressure and winds. NSSL has a mobile, trailer-based boundary layer profiling facility using commercially available sensors. CLAMPS contains

2444-657: Is little or no activity in the area, and a precipitation mode , with a faster scan for tracking active weather. NEXRAD has an increased emphasis on automation , including the use of algorithms and automated volume scans. In the 1970s, the U.S. Departments of Commerce, Defense, and Transportation, agreed that to better serve their operational needs, the existing national radar network needed to be replaced. The radar network consisted of WSR-57 developed in 1957, and WSR-74 developed in 1974. Neither system employed Doppler technology, which provides wind speed and direction information. The Joint Doppler Operational Project (JDOP)

2538-575: Is not always possible with SAILS cuts, as the base 0.5 degree scan travels below the formation of mesovortices at closer distances to the radar. MRLE consecutively scans either the two, three or four lowest scan angles during the middle of a typical volume scan, allowing more frequent surveillance of mesovortex formation during QLCS events. MRLE will be deployed on a non-operational basis in RPG 18.0 in spring of 2018, with possible operational deployment with RPG 19.0, if proven useful or of importance. Deployment

2632-524: Is successful, forecasts likely could improve lead time by factors of 2 to 4 times. The Weather Research and Forecast (WRF) model is the product of a collaboration between the meteorological research and forecasting communities. Working at the interface between research and operations, NSSL scientists have been some of the main contributors to WRF development efforts and continue to provide operational implementation and testing of WRF. The NSSL WRF generates daily, real-time 1- to 36-hour experimental forecasts at

2726-407: The 2011 Super Outbreak , use the images to plan post event damage surveys. Emergency responders use On-Demand to produce high-resolution street maps of affected areas, so they can more effectively begin rescue and recovery efforts and damage assessments. NSSL's Development Lab includes four wall-mounted plasma screen displays and enough room for at least 10 workstations. A large round table occupies

2820-836: The Cooperative Institute for Severe and High-Impact Weather Research and Operations (CIWRO) at the University of Oklahoma that enables collaboration and participation by students and visiting scientists in performing research. The Lab also works closely with the Storm Prediction Center (SPC) and the National Weather Service Norman Forecast Office , which are co-located at the National Weather Center (NWC) in Norman, Oklahoma . The NWC houses

2914-868: The Four Corners region; the area around the Northwest Angle in Minnesota; an area near the Connecticut River in Vermont ; and areas near the borders of the Oklahoma and Texas Panhandles . Notably, many of these gaps lie in tornado alley . At least one tornado has gone undetected by WSR-88D as a result of such a coverage gap – an EF1 tornado in Lovelady, Texas in April 2014. As a result of

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3008-570: The Multi-Radar Multi-Sensor (MRMS) system , and will automatically produce severe weather and precipitation products for improved decision-making capability within NOAA. NSSL: On-Demand is a web-based tool based on WDSS-II that helps confirm when and where severe weather occurred by mapping radar-detected circulations or hail on Google Earth satellite images. National Weather Service (NWS) forecast offices, including those affected by

3102-588: The 1980s. However, it took four years to allow the prospective contractors to develop their proprietary models. Unisys was selected as the contractor, and was awarded a full-scale production contract in January 1990. Installation of an operational prototype was completed in the fall of 1990 in Norman, Oklahoma . The first installation of a WSR-88D for operational use in daily forecasting was in Sterling, Virginia on June 12, 1992. The last system deployed as part of

3196-638: The Cimarron radar, located 15 miles (24 km) west of Oklahoma City. This enabled NSSL to perform dual Doppler experiments while scanning storms with both radars simultaneously. A deliberate decision to collocate research with operations led the National Severe Storms Forecast Center to move from Kansas City to Norman in 1997, changing its name to the Storm Prediction Center. This move would allow for improved collaborations between NSSL and SPC. Some three years later in 2000,

3290-705: The JDOP published a paper providing the concepts for the development and operation of a national weather radar network. In 1979, the NEXRAD Joint System Program Office (JSPO) was formed to move forward with the development and deployment of the proposed NEXRAD radar network. That year, the NSSL completed a formal report on developing the NEXRAD system. When the proposal was presented to the Reagan administration , two options were considered to build

3384-693: The Metropolitan Weather Hazard Protection Act of 2015. The act mandates that any city with a population of 700,000 or more must have Doppler Radar coverage <6,000 feet above ground level. The bill passed the Senate , but died in a House committee. It is not likely that additional WSR-88Ds will be deployed, as the production line was shut down in 1997, and the National Weather Service has an insufficient budget to restart production. In 2011,

3478-605: The NMQ/Q2 project to produce flash flood forecasts at 1-km/5-min resolution. FLASH project development continues to be an active collaboration between members of NSSL's Stormscale Hydrometeorology and Hydromodeling Groups, and the HyDROS Lab at the University of Oklahoma. The Coastal and Inland Flooding Observation and Warning (CI-FLOW) project is a demonstration projection that predicts the combined effects of coastal and inland floods for coastal North Carolina. CI-FLOW captures

3572-688: The NWS Forecast Office in the future. In the 1990s, NSSL developed the Warning Decision Support System, to enhance NWS warning capabilities. NSSL continues to work on the next generation WDSS-II (Warning Decision Support System: Integrated Information/NMQ) , a tool that quickly combines data streams from multiple radars, surface and upper air observations, lightning detection systems, and satellite and forecast models. This improved and expanded system will eventually be moved to National Weather Service operations as

3666-689: The National Weather Service office in Slidell, Louisiana announced that they would move the office's NEXRAD from the office building in Slidell west to Hammond at the end of 2022. Along with a lower elevation angle, the new location would enable lower level monitoring of storm activity in the Baton Rouge area, where the lowest sampling elevation would drop from 4000-6000 feet above the surface to 300-600 feet. The NEXRAD site located in Cayey, Puerto Rico

3760-486: The OKLMA. Thousands of points can be mapped for an individual lightning flash to reveal its location and the development of its structure. NSSL scientists hope to learn more about how storms produce intra-cloud and cloud-to-ground flashes and how each type is related to tornadoes and other severe weather. NSSL researchers are working on products that use GOES satellite data to identify rapidly growing clouds that might indicate

3854-485: The University of Oklahoma built their first Mobile Mesonet (MM) vehicles, a.k.a. “probes,” in 1992. Probes are modified minivans with a suite of weather instruments mounted atop a roof rack and a complex of computer and communication equipment inside. NSSL scientists drive these through storms and storm environments to make measurements of temperature, pressure, humidity and wind. NSSL's 2DVD takes high speed video pictures, from two different angles, of anything falling from

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3948-610: The VCPs based on the type of weather occurring: The specific VCP currently in use at each NEXRAD site is available. Deployed from March to August 2008 with all level II data, the Super Resolution upgrade permitted the capability of the radar to produce much higher resolution data. Under legacy resolution, the WSR-88D provides reflectivity data at 1 km (0.62 mi) by 1 degree to 460 km (290 mi) range, and velocity data at 0.25 km (0.16 mi) by 1 degree to

4042-679: The Warning Decision Support System - Integrated Information (WDSS-II) and the National Mosaic Quantitative Precipitation Estimation system. MRMS is a system with automated algorithms that quickly and intelligently integrate data streams from multiple radars, surface and upper air observations, lightning detection systems, and satellite and forecast models. Numerous two-dimensional multiple-sensor products offer assistance for hail, wind, tornado, quantitative precipitation estimation forecasts, convection, icing, and turbulence diagnosis. The MRMS system

4136-481: The WoF-TTP goal hopes to improve the prediction of other convective weather threats such as large hail and damaging winds. NSSL's Mesoscale Ensemble (NME) is an experimental analysis and short-range ensemble forecast system. These forecasts are designed to be used by forecasters as a 3-D hourly analysis of the environment. The National Mosaic and Multi-sensor Quantitative Precipitation Estimation (NMQ) system uses

4230-445: The advantage of providing useful lead times for all locations downstream of the hazards, and continually removes the warning from areas where threat has already passed. The Flooded Locations And Simulated Hydrographs Project (FLASH) was launched in early 2012 to improve the accuracy and timing of flash flood warnings. FLASH uses forecast models, geographic information, and real-time high-resolution, accurate rainfall observations from

4324-530: The atmosphere allowing operators to examine the vertical structure of storms and could act as wind profilers by providing detailed wind information for several kilometers above the radar site. The radars also had a much increased range allowing detection of weather events at much greater distances from the radar site. WSR-88D development, maintenance, and training are coordinated by the NEXRAD Radar Operations Center (ROC) located on

4418-686: The city—passed over the site after it made landfall. NEXRAD radars based in Houston, Shreveport and Fort Polk were used to fill gaps in radar coverage within portions of Southwestern Louisiana until the Lake Charles site was rebuilt; the NWS Radar Operations Center also deployed a SMART-R vehicle on loan from the University of Oklahoma to provide supplemental radar data on Hurricane Delta in advance of its track into

4512-867: The complex interaction between rainfall, river flows, waves, and tides and storm surge, and how they will impact ocean and river water levels. NSSL, with support from the NOAA National Sea Grant, leads the large and unique interdisciplinary team. In an effort to support NWS forecasters, NSSL investigates methods and techniques to diagnose severe weather events more quickly and accurately. NSSL has more than ten NWS workstations—the Advanced Weather Interactive Processing System 2 (AWIPS2) —available for use in product evaluation. NSSL uses these AWIPS2 stations to test and demonstrate warning products and techniques that have been developed here that will be available in

4606-586: The continental United States, often for terrain or budgetary reasons, or remoteness of the area. Such notable gaps include most of Alaska ; several areas of Oregon , including the central and southern coast and much of the area east of the Cascade Mountains; many portions of the Rocky Mountains ; Pierre, South Dakota ; portions of northern Texas ; large portions of the Nebraska panhandle ;

4700-631: The coverage gap, initial reports of tornadic activity were treated with skepticism by the local National Weather Service forecast office. Coverage gaps can also be caused during radar outages, especially in areas with little to no overlapping coverage. For example, a hardware failure on July 16, 2013 resulted in an outage and coverage gap for the Albany, New York area that lasted through early August. A coverage gap in North Carolina encouraged Senator Richard Burr to propose S. 2058, also known as

4794-410: The creation of new techniques, strategies and applications to better estimate and forecast precipitation amounts, locations and types. The National Mosaic and Multi-sensor Quantitative Precipitation Estimation system (NMQ) uses a combination of observing systems ranging from radars to satellites on a national scale to produce precipitation forecasts. The MRMS system is the proposed operational version of

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4888-475: The current Air Route Surveillance Radar network, saving the United States government billions of dollars in maintenance costs. The National Severe Storms Laboratory predicts that a phased array system will eventually replace the current network of WSR-88D radar transmitters. NEXRAD data is used in multiple ways. It is used by National Weather Service meteorologists and (under provisions of U.S. law )

4982-442: The current NEXRAD network in working order for as long as possible. These improvements include Signal Processor upgrades, Pedestal upgrades, Transmitter upgrades, and shelter upgrades. The program is anticipated to be finished by 2022, which coincides with the beginnings of a nationwide implementation of Multi-function Phased Array Radars (see below). WSR-88D has coverage gaps below 10,000 feet (or no coverage at all) in many parts of

5076-546: The first Doppler weather radar became operational in Norman in 1974, NSSL has worked to extend its functionality, and proved to the NOAA National Weather Service (NWS) that Doppler weather radar was important as a nowcasting tool. The NWS now has a network of 158 NEXRADs. Dual-polarized (dual-pol) radar technology is truly a NOAA-wide accomplishment. NSSL spent nearly 30 years researching and developing

5170-570: The first NOAA Hazardous Weather Testbed (HWT) Spring Experiment took place. This would become an annual event to evaluate operational and experimental models and algorithms with the NWS. NSSL is organized into three primary divisions: Forecasting a Continuum of Environmental Threats (FACETs) serves as a broad-based framework and strategy to help focus and direct efforts related to next-generation science, technology and tools for forecasting environmental hazards. FACETS will address grid-based probabilistic threats, storm-scale observations and guidance,

5264-402: The forecaster, threat grid tools, useful output, effective response, and verification. The Warn-on-Forecast (WoF) research project aims to deliver a set of technologies for FACETs on a variety of space and time scales. WoF aims to create computer-model projections that accurately predict storm-scale phenomena such as tornadoes, large hail, and extremely localized rainfall. If Warn-on-Forecast

5358-493: The forecaster, threat grid tools, useful output, effective response, and verification. The Multi-Year Reanalysis Of Remotely-Sensed Storms (MYRORSS – pronounced “mirrors”) NSSL and the National Climatic Data Center (NCDC) to reconstruct and evaluate numerical model output and radar products derived from 15 years of WSR-88D data over the coterminous U.S. (CONUS). The end result of this research will be

5452-432: The ground causing damage. Dual-pol is the most significant enhancement made to the nation's radar network since Doppler radar was first installed in the early 1990s. More than 350 FAA radars and by 2025, nearly 150 of the nation's Doppler weather radars will need to be either replaced or have their service life extended. Phased array radars have been used by the military for many years to track aircraft. NSSL's MPAR program

5546-514: The grounds of the University of Oklahoma Westheimer Airport (KOUN) in Norman, Oklahoma. The University of Louisiana at Monroe in Monroe, Louisiana operates a "WSR-88D clone" radar that is used by local National Weather Service offices in Shreveport , Little Rock and Jackson to fill gaps in NEXRAD coverage in northeastern Louisiana, southeastern Arkansas and western Mississippi. However,

5640-587: The installation program was installed in North Webster, Indiana on August 30, 1997. In 2011, the new Langley Hill NEXRAD was added at Langley Hill, Washington to better cover the Pacific Coast of that area; other radars also filled gaps in coverage at Evansville, Indiana and Ft. Smith, Arkansas , following the initial installations. The site locations were strategically chosen to provide overlapping coverage between radars in case one failed during

5734-417: The middle of the room for lunchtime “brown bag” discussions and other meetings. Researchers, forecasters and developers are using the lab to evaluate new platforms and techniques in real-time as a team. The workstations in the lab can be quickly adapted for visualization and incorporation of unique data sources including dual-pol and phased array radars. NSSL created a powerful research and development tool for

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5828-444: The national WSR-88D radar network and NCEP's North American Mesoscale model product to automatically locate regions of thunderstorm activity. It is able to identify deep rotating updrafts that indicate a supercell thunderstorm at 1 km resolution every five minutes in these regions. NSSL participates in field research projects to collect weather data to increase knowledge about thunderstorm behavior and thunderstorm hazards. PECAN

5922-478: The need for hardware upgrades AVSET was initially deployed in RPG build 12.3, in Fall of 2011. One of the primary weaknesses of the WSR-88D radar system was the lack of frequency of base (0.5 degree) scans, especially during severe weather. Forecasters, and TV viewers at home, often had access to images that were four or five minutes old, and therefore had inaccurate information. TV viewers at home could be lulled into

6016-572: The need of more frequent low-level scans during quasi-linear convective systems (QLCSs). During QLCSs, it is not uncommon for brief and otherwise un-noticeable mesovortices to spawn at points along the line. Due to untimely radar data and time being taken to complete the entire volume, these vortices often spawn without warning or prior notice. With MRLE, the operator has the choice between 2 and 4 low-level scans. Unlike MESO-SAILS , which scans at one angle and can only do up to 3 low-level scans per volume, MRLE scans at 4 possible angles, and can cut into

6110-459: The operator. All NEXRADs have a dish diameter of 9.1 m (30 ft) and an aperture diameter of 8.5 m (28 ft). Using the predetermined VCPs, NEXRADs have a traditional elevation minimum and maximum ranging from 0.1 to 19.5 degrees, although the non-operational minimum and maximum spans from −1 to +45 degrees. Unlike its predecessor, the WSR-74 , the antenna can not be manually steered by

6204-522: The operator. WSR-88D Level I data is the recorded output of the digital receiver. Spatial resolution varies with data type and scan angle – level III data has a resolution of 1 km x 1 degree in azimuth, while super-res level II, (implemented in 2008 nationwide), has a resolution of 250m by 0.5 degrees in azimuth below 2.4 degrees in elevation. The NEXRAD radar system continually refreshes its three-dimensional database via one of several predetermined scan patterns. These patterns have differing PRFs to fit

6298-509: The public about dangerous storms. NEXRAD data also provides information about rainfall rate and aids in hydrological forecasting. Data is provided to the public in several forms, the most basic form being graphics published to the NWS website. Data is also available in two similar, but different, raw formats. Available directly from the NWS is Level III data, consisting of reduced resolution, low- bandwidth base products as well as many derived, post-processed products; Level II data consists of only

6392-406: The radar systems: allow corporate bids to build the systems based on the schematics of the previously developed prototype radar or seek contractors to build their own systems using predetermined specifications. The JSPO group opted to select a contractor to develop and produce the radars that would be used for the national network. Radar systems developed by Raytheon and Unisys were tested during

6486-466: The radar to distinguish between rain, hail, and snow, something the horizontally polarized radars cannot accurately do. Early trials showed that rain, ice pellets , snow, hail, birds, insects, and ground clutter all have different signatures with dual polarization, which could mark a significant improvement in forecasting winter storms and severe thunderstorms. The deployment of the dual polarization capability (Build 12) to NEXRAD sites began in 2010 and

6580-430: The radar's status as being part of the NEXRAD network is disputed. A standard WSR-88D operates in the S band , at a frequency of around 2800 MHz, with a typical gain around 53 dB using a center-fed parabolic antenna. The pulse repetition frequency (PRF) varies from 318 to 1300 Hz with a maximum power output of 700 kW at Klystron output, although dependent on the volume coverage pattern (VCP) selected by

6674-604: The radar, the researchers found a pattern that showed the tornado beginning to form before it could be visually detected on the film. The researchers named this phenomenon the Tornado Vortex Signature (TVS). Research using this radar led to the concept that would later go on to become the NWS NEXRAD WSR-88D radar network. In 1973, the Laboratory commissioned a second Doppler weather radar, named

6768-501: The range at which tornadic mesoscale rotations can be detected. This allows for faster lead time on warnings and extends the useful range of the radar. The increased resolution (in both azimuth and range) increases the detail of such rotations, giving a more accurate representation of the storm. Along with providing better detail of detected precipitation and other mesoscale features, Super Resolution also provides additional detail to aid in other severe storm analysis. Super Resolution extends

6862-433: The range of velocity data and provides it faster than before, also allowing for faster lead time on potential tornado detection and subsequent warnings. WSR-88D sites across the nation have been upgraded to polarimetric radar , which adds a vertical polarization to the traditional horizontally polarized radar waves, in order to more accurately discern what is reflecting the signal. This so-called dual polarization allows

6956-506: The region (nearly paralleling that of Hurricane Laura) in late October. Operational service to the Lake Charles NEXRAD radar site was restored in January 2021, following a four-month, $ 1.65-million reconstruction project that included the replacement of the radome and internal equipment and repairs to the station's radome pedestal, tower, fence and equipment shelters. On May 24, 2023, the NEXRAD radar site located on Guam ,

7050-671: The remainder of the NSSP moved to Norman, where it merged with WRL and was renamed the National Severe Storms Laboratory (NSSL). Dr. Edwin Kessler became the first director. In 1969, NSSL obtained a surplus 10-cm pulse-Doppler radar from the United States Air Force. This radar was used to scan and film the complete life cycle of a tornado in 1973. By comparing the film with velocity images from

7144-402: The respective use, but all have a constant resolution. Since the system samples the atmosphere in three dimensions, there are many variables that can be changed, depending on the desired output. With all traditional VCPs, the antenna scans at a maximum of 19.5 degrees in elevation, and a minimum of .5, with some coastal sites scanning as low as .2 or lower. Due to the incomplete elevation coverage,

7238-434: The sky through its viewing area (such as raindrops, hail or snow). It is used in polarimetric radar studies by measuring rain rate, drop shape and size distribution, and other parameters useful in narrowing down the accuracy of precipitation identification algorithms. NSSL has available small portable weather platforms with sensors that measure temperature, pressure, moisture, wind speed and direction, and an instrument called

7332-503: The structure of the boundary layer, shallow convective cloud processes, the interaction between clouds, aerosols, radiation, precipitation and the thermodynamic environment, mixed phase clouds, and more. Numerical models, such as those used for climate and weather prediction, have large uncertainties in all of these areas. Researchers also use these observations to improve our understanding and representation of these processes. NEXRAD NEXRAD or Nexrad ( Next-Generation Radar )

7426-455: The technology. The National Weather Service (NWS) and NSSL developed the specifications for the modification, which was tested by engineers at the NWS Radar Operations Center. The NWS Warning Decision Training Branch provided timely and relevant training to all NWS forecasters who would be using the technology. The upgraded radars offer 14 new radar products to better determine the type and intensity of precipitation, and can confirm tornadoes are on

7520-496: The transition of promising new meteorological insights and technologies into advances in forecasting and warning for hazardous mesoscale weather events throughout the United States. One of the new warning methodologies being tested in the NOAA Hazardous Weather Testbed is the “Threats-In-Motion” (TIM) concept. TIM warning grids update every minute and move continuously with the path of the storm. TIM has

7614-616: The world to collect weather measurements around and under thunderstorms that could produce tornadoes. The Verification of the Origins of Rotation in Tornadoes EXperiment was a two-year project designed to verify a number of ongoing questions about the causes of tornado formation. A new mobile Doppler radar was used and provided revolutionary data on several tornadic storms. The TOtable TOrnado Observatory (TOTO) , developed by NOAA Environmental Research Laboratory scientists,

7708-409: Was a 55-gallon barrel outfitted with anemometers, pressure sensors, and humidity sensors, along with devices to record the data. In theory, a team would roll TOTO out of the back of the pickup in the path of a tornado, switch on the instruments, and get out of the way. Several groups tried to deploy TOTO over the years, but never took a direct hit. The closest TOTO ever came to success was in 1984 when it

7802-628: Was an extensive field project that focused on nighttime convection. PECAN was conducted across northern Oklahoma, central Kansas and into south-central Nebraska from 1 June to 15 July 2015. NSSL participated in the Verification of the Origins of Rotation in Tornadoes EXperiment 2009-2010 , an extensive project studying small scale kinematics, atmospheric variables and when and why tornadoes form. The National Oceanic and Atmospheric Administration (NOAA) and National Science Foundation (NSF) supported more than 100 scientists, students and staff from around

7896-501: Was anticipated by the Radar Operations Center to commence in October 2017, along with the RPG 18.0 build, on a non-operational basis. The scanning option will only be available for use with Volume Coverage Patterns 21, 12, 212, and additionally 215. If proven to be significant in terms of warning dissemination, MRLE will deploy operationally nationwide with RPG 18.0, planned for 2018. The concept of MRLE derives from

7990-477: Was completed by the summer of 2013. The radar at Vance Air Force Base in Enid, Oklahoma was the first operational WSR-88D modified to utilize dual polarization technology. The modified radar went into operation on March 3, 2011. When the NEXRAD system was initially implemented, the radar automatically scanned all scan angles in a Volume Coverage Pattern, even if the highest scan angles were free of precipitation. As

8084-559: Was damaged by Typhoon Mawar as the eye of the Category 4 typhoon passed over the northern end of the island. After initially being restored back into operation, the installation suffered from ongoing issues and, as of April 24, 2024, has been reported as "unserviceable" in NOTAMs. Future plans for restoring weather radar to Guam and the CNMI are unknown. The National Weather Service keeps

8178-500: Was designed to detect very high wind speeds in tornadoes, but could not determine the distance to the tornadoes. In 1963, the Weather Radar Laboratory (WRL) was established in Norman and, in the following year, engineers modified the radar to transmit in pulses. The pulse-Doppler radar could receive data in between each transmit pulse, eliminating the need for two antennas and solving the distance problem. In 1964,

8272-560: Was destroyed during the passage of Hurricane Maria through the region in September 2017. In addition to a neighboring Terminal Doppler Weather Radar (TDWR) site that was rendered temporarily inoperable but ultimately survived, the Department of Defense deployed two short-range X-band radars on the island to provide radar coverage until the FAA-maintained NEXRAD site was restored. In June 2018, this NEXRAD radar site

8366-403: Was developed to produce severe weather and precipitation products for improved decision-making capability to improve severe weather forecasts and warnings, hydrology, aviation, and numerical weather prediction. A weather-adaptive three-dimensional variational data assimilation (3DVAR) system from NSSL/CIWRO automatically detects and analyzes supercell thunderstorms. The 3DVAR system uses data from

8460-520: Was executed for approximately 4.5 hours and during the testing, an Electronics Technician observed the pedestal/antenna assembly's behavior. No excessive wear was noted. Two days later, SAILSx3 was executed, which added 3 additional low-level scans to a volume. During this 1.5 hour test of SAILSx3, a ROC Radar Hardware Engineer accompanied the ROC Electronics Technician to observe the antenna/pedestal assembly. Again, no excessive wear

8554-589: Was formed in 1976 at the National Severe Storms Laboratory (NSSL) to study the usefulness of using Doppler weather radar to identify severe and tornadic thunderstorms . Tests over the next three years, conducted by the National Weather Service and the Air Weather Service agency of the U.S. Air Force , found that Doppler radar provided much improved early detection of severe thunderstorms. A working group that included

8648-654: Was noted. MESO-SAILS was deployed with Build 16.1, in spring of 2016. Mid-Volume Rescan of Low-Level Elevations (colloquially known as M.R.L.E. ) is a dynamic scanning option for the WSR-88D derived from MESO-SAILS , a separate scanning option implemented in NEXRAD RPG 14.0, in the Spring of 2014. During quasi-linear convective systems (QLCS), colloquially known as squall lines, the detection of mesovortices , which generate at 4,000 to 8,000 feet above ground level,

8742-464: Was restored to fully operational condition and was reinforced with several lightning rods and secured with a stronger fiberglass dome that included using more than 3,000 bolts. On August 27, 2020, the NEXRAD radar site located in Lake Charles, Louisiana , was destroyed by Hurricane Laura as the eye of the Category 4 storm—which packed wind gusts recorded around 135 mph (217 km/h) in

8836-445: Was sideswiped by the edge of a weak tornado and was knocked over. TOTO was retired in 1987. Aircraft flew into thunderstorms to measure turbulence in the 1960s, 1970s and early 1980s. This data was combined with measurements of the intensity of the rain from nearby WSR-57s to understand how thunderstorm echoes and turbulence are related, with the goal of improving short-term turbulence forecasts. Scientists and technicians from NSSL and

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