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135-416: 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 is little or no activity in the area, and a precipitation mode , with

270-709: 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

405-487: A biological context to complement large-scale bird monitoring schemes. A special case of a radar wind profiler is a vertical precipitation profiler. It has a single vertical axis of unistatic or bistatic configuration. It is used to measure precipitation only. It can be used to identify the melting height of precipitation. These type of radars have been used to study the interactions of different freezing levels and atmospheric rivers on flooding in lowland mountains of

540-499: A channel around 11 micron wavelength and primarily give information about cloud tops. Due to the typical structure of the atmosphere, cloud-top temperatures are approximately inversely related to cloud-top heights, meaning colder clouds almost always occur at higher altitudes. Further, cloud tops with a lot of small-scale variation are likely to be more vigorous than smooth-topped clouds. Various mathematical schemes, or algorithms, use these and other properties to estimate precipitation from

675-705: A dramatic effect on agriculture. All plants need at least some water to survive, therefore rain (being the most effective means of watering) is important to agriculture. While a regular rain pattern is usually vital to healthy plants, too much or too little rainfall can be harmful, even devastating to crops. Drought can kill crops and increase erosion, while overly wet weather can cause harmful fungus growth. Plants need varying amounts of rainfall to survive. For example, certain cacti require small amounts of water, while tropical plants may need up to hundreds of inches of rain per year to survive. In areas with wet and dry seasons, soil nutrients diminish and erosion increases during

810-436: 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

945-586: 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)

1080-556: 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

1215-736: 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,

1350-425: A layer of above-freezing air exists with sub-freezing air both above and below. This causes the partial or complete melting of any snowflakes falling through the warm layer. As they fall back into the sub-freezing layer closer to the surface, they re-freeze into ice pellets. However, if the sub-freezing layer beneath the warm layer is too small, the precipitation will not have time to re-freeze, and freezing rain will be

1485-499: 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

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1620-411: A physical barrier such as a mountain ( orographic lift ). Conductive cooling occurs when the air comes into contact with a colder surface, usually by being blown from one surface to another, for example from a liquid water surface to colder land. Radiational cooling occurs due to the emission of infrared radiation , either by the air or by the surface underneath. Evaporative cooling occurs when moisture

1755-453: A portion of the atmosphere becomes saturated with water vapor (reaching 100% relative humidity ), so that the water condenses and "precipitates" or falls. Thus, fog and mist are not precipitation; their water vapor does not condense sufficiently to precipitate, so fog and mist do not fall. (Such a non-precipitating combination is a colloid .) Two processes, possibly acting together, can lead to air becoming saturated with water vapor: cooling

1890-470: 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

2025-476: 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

2160-567: A single year. A significant portion of the annual precipitation in any particular place (no weather station in Africa or South America were considered) falls on only a few days, typically about 50% during the 12 days with the most precipitation. The Köppen classification depends on average monthly values of temperature and precipitation. The most commonly used form of the Köppen classification has five primary types labeled A through E. Specifically,

2295-409: A slow-falling drizzle , which has been observed as Rain puddles at its equator and polar regions. Precipitation is a major component of the water cycle , and is responsible for depositing most of the fresh water on the planet. Approximately 505,000 km (121,000 cu mi) of water falls as precipitation each year, 398,000 km (95,000 cu mi) of it over the oceans. Given

2430-752: A subject of research. Although the ice is clear, scattering of light by the crystal facets and hollows/imperfections mean that the crystals often appear white in color due to diffuse reflection of the whole spectrum of light by the small ice particles. The shape of the snowflake is determined broadly by the temperature and humidity at which it is formed. Rarely, at a temperature of around −2 °C (28 °F), snowflakes can form in threefold symmetry—triangular snowflakes. The most common snow particles are visibly irregular, although near-perfect snowflakes may be more common in pictures because they are more visually appealing. No two snowflakes are alike, as they grow at different rates and in different patterns depending on

2565-407: A variety of datasets possessing different formats, time/space grids, periods of record and regions of coverage, input datasets, and analysis procedures, as well as many different forms of dataset version designators. In many cases, one of the modern multi-satellite data sets is the best choice for general use. The likelihood or probability of an event with a specified intensity and duration is called

2700-529: 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

2835-420: Is IC. Occult deposition occurs when mist or air that is highly saturated with water vapour interacts with the leaves of trees or shrubs it passes over. Stratiform or dynamic precipitation occurs as a consequence of slow ascent of air in synoptic systems (on the order of cm/s), such as over surface cold fronts , and over and ahead of warm fronts . Similar ascent is seen around tropical cyclones outside of

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2970-410: Is RA, while the coding for rain showers is SHRA. Ice pellets or sleet are a form of precipitation consisting of small, translucent balls of ice. Ice pellets are usually (but not always) smaller than hailstones. They often bounce when they hit the ground, and generally do not freeze into a solid mass unless mixed with freezing rain . The METAR code for ice pellets is PL . Ice pellets form when

3105-482: Is a grassland biome located in semi-arid to semi-humid climate regions of subtropical and tropical latitudes, with rainfall between 750 and 1,270 mm (30 and 50 in) a year. They are widespread on Africa, and are also found in India, the northern parts of South America, Malaysia, and Australia. The humid subtropical climate zone is where winter rainfall (and sometimes snowfall) is associated with large storms that

3240-480: Is a stable cloud deck which tends to form when a cool, stable air mass is trapped underneath a warm air mass. It can also form due to the lifting of advection fog during breezy conditions. There are four main mechanisms for cooling the air to its dew point: adiabatic cooling, conductive cooling, radiational cooling , and evaporative cooling. Adiabatic cooling occurs when air rises and expands. The air can rise due to convection , large-scale atmospheric motions, or

3375-449: Is a time when air quality improves, freshwater quality improves, and vegetation grows significantly. Soil nutrients diminish and erosion increases. Animals have adaptation and survival strategies for the wetter regime. The previous dry season leads to food shortages into the wet season, as the crops have yet to mature. Developing countries have noted that their populations show seasonal weight fluctuations due to food shortages seen before

3510-449: Is a type of weather observing equipment that uses radar or sound waves ( SODAR ) to detect the wind speed and direction at various elevations above the ground. Readings are made at each kilometer above sea level, up to the extent of the troposphere (i.e., between 8 and 17 km above mean sea level). Above this level there is inadequate water vapor present to produce a radar "bounce." The data synthesized from wind direction and speed

3645-582: Is accompanied by plentiful precipitation year-round. The Mediterranean climate regime resembles the climate of the lands in the Mediterranean Basin, parts of western North America, parts of western and southern Australia, in southwestern South Africa and in parts of central Chile. The climate is characterized by hot, dry summers and cool, wet winters. A steppe is a dry grassland. Subarctic climates are cold with continuous permafrost and little precipitation. Precipitation, especially rain, has

3780-620: Is added to the air through evaporation, which forces the air temperature to cool to its wet-bulb temperature , or until it reaches saturation. The main ways water vapor is added to the air are: wind convergence into areas of upward motion, precipitation or virga falling from above, daytime heating evaporating water from the surface of oceans, water bodies or wet land, transpiration from plants, cool or dry air moving over warmer water, and lifting air over mountains. Coalescence occurs when water droplets fuse to create larger water droplets, or when water droplets freeze onto an ice crystal, which

3915-437: Is associated with their warm front is often extensive, forced by weak upward vertical motion of air over the frontal boundary which condenses as it cools and produces precipitation within an elongated band, which is wide and stratiform , meaning falling out of nimbostratus clouds. When moist air tries to dislodge an arctic air mass, overrunning snow can result within the poleward side of the elongated precipitation band . In

4050-408: Is by temperature fluctuations (in mono-static systems), or by both temperature and wind velocity fluctuations (in bi-static systems). Mono-static antenna systems can be divided further into two categories: those using multiple axis, individual antennas and those using a single phased array antenna. The multiple-axis systems generally use three individual antennas aimed in specific directions to steer

4185-487: Is equally distributed through the year. Some areas with pronounced rainy seasons will see a break in rainfall mid-season when the Intertropical Convergence Zone or monsoon trough move poleward of their location during the middle of the warm season. When the wet season occurs during the warm season, or summer, rain falls mainly during the late afternoon and early evening hours. The wet season

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4320-416: Is filled by 2.5 cm (0.98 in) of rain, with overflow flowing into the outer cylinder. Plastic gauges have markings on the inner cylinder down to 1 ⁄ 4  mm (0.0098 in) resolution, while metal gauges require use of a stick designed with the appropriate 1 ⁄ 4  mm (0.0098 in) markings. After the inner cylinder is filled, the amount inside is discarded, then filled with

4455-401: Is intermittent and often associated with baroclinic boundaries such as cold fronts , squall lines , and warm fronts. Convective precipitation mostly consist of mesoscale convective systems and they produce torrential rainfalls with thunderstorms, wind damages, and other forms of severe weather events. Orographic precipitation occurs on the windward (upwind) side of mountains and is caused by

4590-759: Is known as the Bergeron process . The fall rate of very small droplets is negligible, hence clouds do not fall out of the sky; precipitation will only occur when these coalesce into larger drops. droplets with different size will have different terminal velocity that cause droplets collision and producing larger droplets, Turbulence will enhance the collision process. As these larger water droplets descend, coalescence continues, so that drops become heavy enough to overcome air resistance and fall as rain. Raindrops have sizes ranging from 5.1 to 20 millimetres (0.20 to 0.79 in) mean diameter, above which they tend to break up. Smaller drops are called cloud droplets, and their shape

4725-540: Is made, various networks exist across the United States and elsewhere where rainfall measurements can be submitted through the Internet, such as CoCoRAHS or GLOBE . If a network is not available in the area where one lives, the nearest local weather office will likely be interested in the measurement. A concept used in precipitation measurement is the hydrometeor. Any particulates of liquid or solid water in

4860-574: 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

4995-431: Is possible within a cyclone's comma head and within lake effect precipitation bands. In mountainous areas, heavy precipitation is possible where upslope flow is maximized within windward sides of the terrain at elevation. On the leeward side of mountains, desert climates can exist due to the dry air caused by compressional heating. Most precipitation occurs within the tropics and is caused by convection . The movement of

5130-435: 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 the base products, but at their original resolution. Because of

5265-519: Is spherical. As a raindrop increases in size, its shape becomes more oblate , with its largest cross-section facing the oncoming airflow. Contrary to the cartoon pictures of raindrops, their shape does not resemble a teardrop. Intensity and duration of rainfall are usually inversely related, i.e., high intensity storms are likely to be of short duration and low intensity storms can have a long duration. Rain drops associated with melting hail tend to be larger than other rain drops. The METAR code for rain

5400-489: Is the temperature to which a parcel of air must be cooled in order to become saturated, and (unless super-saturation occurs) condenses to water. Water vapor normally begins to condense on condensation nuclei such as dust, ice, and salt in order to form clouds. The cloud condensation nuclei concentration will determine the cloud microphysics. An elevated portion of a frontal zone forces broad areas of lift, which form cloud decks such as altostratus or cirrostratus . Stratus

5535-457: Is the time of year, covering one or more months, when most of the average annual rainfall in a region falls. The term green season is also sometimes used as a euphemism by tourist authorities. Areas with wet seasons are dispersed across portions of the tropics and subtropics. Savanna climates and areas with monsoon regimes have wet summers and dry winters. Tropical rainforests technically do not have dry or wet seasons, since their rainfall

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5670-492: 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 the public about dangerous storms. NEXRAD data also provides information about rainfall rate and aids in hydrological forecasting. Data

5805-400: Is typically active when freezing rain occurs. A stationary front is often present near the area of freezing rain and serves as the focus for forcing moist air to rise. Provided there is necessary and sufficient atmospheric moisture content, the moisture within the rising air will condense into clouds, namely nimbostratus and cumulonimbus if significant precipitation is involved. Eventually,

5940-407: Is very useful to meteorological forecasting and timely reporting for flight planning. A twelve-hour history of data is available through NOAA websites. In a typical implementation, the radar or sodar can sample along each of five beams: one is aimed vertically to measure vertical velocity, and four are tilted off vertical and oriented orthogonal to one another to measure the horizontal components of

6075-451: Is ½ the wavelength of the radar, or approximately 16 centimeters (cm) for a UHF profiler. A boundary-layer radar wind profiler can be configured to compute averaged wind profiles for periods ranging from a few minutes to an hour. Boundary-layer radar wind profilers are often configured to sample in more than one mode. For example, in a “low mode,” the pulse of energy transmitted by the profiler may be 60 m in length. The pulse length determines

6210-868: 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

6345-678: The Great Basin and Mojave Deserts . Similarly, in Asia, the Himalaya mountains create an obstacle to monsoons which leads to extremely high precipitation on the southern side and lower precipitation levels on the northern side. Extratropical cyclones can bring cold and dangerous conditions with heavy rain and snow with winds exceeding 119 km/h (74 mph), (sometimes referred to as windstorms in Europe). The band of precipitation that

6480-459: The electromagnetic spectrum that theory and practice show are related to the occurrence and intensity of precipitation. The sensors are almost exclusively passive, recording what they see, similar to a camera, in contrast to active sensors ( radar , lidar ) that send out a signal and detect its impact on the area being observed. Satellite sensors now in practical use for precipitation fall into two categories. Thermal infrared (IR) sensors record

6615-446: The eyewall , and in comma-head precipitation patterns around mid-latitude cyclones . A wide variety of weather can be found along an occluded front, with thunderstorms possible, but usually their passage is associated with a drying of the air mass. Occluded fronts usually form around mature low-pressure areas. Precipitation may occur on celestial bodies other than Earth. When it gets cold, Mars has precipitation that most likely takes

6750-468: The monsoon trough , or Intertropical Convergence Zone , brings rainy seasons to savannah regions. Precipitation is a major component of the water cycle , and is responsible for depositing fresh water on the planet. Approximately 505,000 cubic kilometres (121,000 cu mi) of water falls as precipitation each year: 398,000 cubic kilometres (95,000 cu mi) over oceans and 107,000 cubic kilometres (26,000 cu mi) over land. Given

6885-425: The return period or frequency. The intensity of a storm can be predicted for any return period and storm duration, from charts based on historical data for the location. The term 1 in 10 year storm describes a rainfall event which is rare and is only likely to occur once every 10 years, so it has a 10 percent likelihood any given year. The rainfall will be greater and the flooding will be worse than

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7020-638: 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

7155-738: The Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres (39 in), but over land it is only 715 millimetres (28.1 in). Climate classification systems such as the Köppen climate classification system use average annual rainfall to help differentiate between differing climate regimes. Global warming is already causing changes to weather, increasing precipitation in some geographies, and reducing it in others, resulting in additional extreme weather . Precipitation may occur on other celestial bodies. Saturn's largest satellite , Titan , hosts methane precipitation as

7290-610: The Earth's surface area, that means the globally averaged annual precipitation is 990 millimetres (39 in). Mechanisms of producing precipitation include convective, stratiform , and orographic rainfall. Convective processes involve strong vertical motions that can cause the overturning of the atmosphere in that location within an hour and cause heavy precipitation, while stratiform processes involve weaker upward motions and less intense precipitation. Precipitation can be divided into three categories, based on whether it falls as liquid water, liquid water that freezes on contact with

7425-535: The IR data. The second category of sensor channels is in the microwave part of the electromagnetic spectrum. The frequencies in use range from about 10 gigahertz to a few hundred GHz. Channels up to about 37 GHz primarily provide information on the liquid hydrometeors (rain and drizzle) in the lower parts of clouds, with larger amounts of liquid emitting higher amounts of microwave radiant energy . Channels above 37 GHz display emission signals, but are dominated by

7560-703: 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

7695-690: 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,

7830-688: 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

7965-807: The Northern Hemisphere, poleward is towards the North Pole, or north. Within the Southern Hemisphere, poleward is towards the South Pole, or south. Southwest of extratropical cyclones, curved cyclonic flow bringing cold air across the relatively warm water bodies can lead to narrow lake-effect snow bands. Those bands bring strong localized snowfall which can be understood as follows: Large water bodies such as lakes efficiently store heat that results in significant temperature differences (larger than 13 °C or 23 °F) between

8100-491: 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 ) is freely available to users outside of the NWS, including researchers , media , and private citizens . The primary goal of NEXRAD data

8235-663: 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

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8370-457: 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 the current Air Route Surveillance Radar network, saving

8505-410: The acoustic beam. One antenna is generally aimed vertically, and the other two are tilted slightly from the vertical at an orthogonal angle. Each of the individual antennas may use a single transducer focused into a parabolic reflector to form a parabolic loudspeaker , or an array of speaker drivers and horns ( transducers ) all transmitting in-phase to form a single beam. Both the tilt angle from

8640-1000: The action of solid hydrometeors (snow, graupel, etc.) to scatter microwave radiant energy. Satellites such as the Tropical Rainfall Measuring Mission (TRMM) and the Global Precipitation Measurement (GPM) mission employ microwave sensors to form precipitation estimates. Additional sensor channels and products have been demonstrated to provide additional useful information including visible channels, additional IR channels, water vapor channels and atmospheric sounding retrievals. However, most precipitation data sets in current use do not employ these data sources. The IR estimates have rather low skill at short time and space scales, but are available very frequently (15 minutes or more often) from satellites in geosynchronous Earth orbit. IR works best in cases of deep, vigorous convection—such as

8775-414: The air or adding water vapor to the air. Precipitation forms as smaller droplets coalesce via collision with other rain drops or ice crystals within a cloud. Short, intense periods of rain in scattered locations are called showers . Moisture that is lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed by the low temperature into clouds and rain. This process

8910-434: The air's motion. A profiler's ability to measure winds is based on the assumption that the turbulent eddies that induce scattering are carried along by the mean wind. The energy scattered by these eddies and received by the profiler is orders of magnitude smaller than the energy transmitted. However, if sufficient samples can be obtained, then the amplitude of the energy scattered by these eddies can be clearly identified above

9045-529: 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

9180-497: The atmosphere are known as hydrometeors. Formations due to condensation, such as clouds, haze , fog, and mist, are composed of hydrometeors. All precipitation types are made up of hydrometeors by definition, including virga , which is precipitation which evaporates before reaching the ground. Particles blown from the Earth's surface by wind, such as blowing snow and blowing sea spray, are also hydrometeors , as are hail and snow . Although surface precipitation gauges are considered

9315-413: The atmosphere due to their mass, and may collide and stick together in clusters, or aggregates. These aggregates are snowflakes, and are usually the type of ice particle that falls to the ground. Guinness World Records list the world's largest snowflakes as those of January 1887 at Fort Keogh , Montana; allegedly one measured 38 cm (15 in) wide. The exact details of the sticking mechanism remain

9450-484: The average time between observations exceeds three hours. This several-hour interval is insufficient to adequately document precipitation because of the transient nature of most precipitation systems as well as the inability of a single satellite to appropriately capture the typical daily cycle of precipitation at a given location. Since the late 1990s, several algorithms have been developed to combine precipitation data from multiple satellites' sensors, seeking to emphasize

9585-449: The background noise level, then the mean wind speed and direction within the volume being sampled can be determined. The radial components measured by the tilted beams are the vector sum of the horizontal motion of the air toward or away from the radar and any vertical motion present in the beam. Using appropriate trigonometry, the three-dimensional meteorological velocity components (u,v,w) and wind speed and wind direction are calculated from

9720-418: The backscattered energy is determined, and then used to calculate the velocity of the air toward or away from the radar along each beam as a function of altitude. The source of the backscattered energy (radar “targets”) is small-scale turbulent fluctuations that induce irregularities in the radio refractive index of the atmosphere. The radar is most sensitive to scattering by turbulent eddies whose spatial scale

9855-531: The best analyses of gauge data take two months or more after the observation time to undergo the necessary transmission, assembly, processing and quality control. Thus, precipitation estimates that include gauge data tend to be produced further after the observation time than the no-gauge estimates. As a result, while estimates that include gauge data may provide a more accurate depiction of the "true" precipitation, they are generally not suited for real- or near-real-time applications. The work described has resulted in

9990-420: The best instantaneous satellite estimate. In either case, the less-emphasized goal is also considered desirable. One key aspect of multi-satellite studies is the ability to include even a small amount of surface gauge data, which can be very useful for controlling the biases that are endemic to satellite estimates. The difficulties in using gauge data are that 1) their availability is limited, as noted above, and 2)

10125-532: The changing temperature and humidity within the atmosphere through which they fall on their way to the ground. The METAR code for snow is SN, while snow showers are coded SHSN. Diamond dust, also known as ice needles or ice crystals, forms at temperatures approaching −40 °C (−40 °F) due to air with slightly higher moisture from aloft mixing with colder, surface-based air. They are made of simple ice crystals, hexagonal in shape. The METAR identifier for diamond dust within international hourly weather reports

10260-686: 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

10395-447: The cloud droplets will grow large enough to form raindrops and descend toward the Earth where they will freeze on contact with exposed objects. Where relatively warm water bodies are present, for example due to water evaporation from lakes, lake-effect snowfall becomes a concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones . Lake-effect snowfall can be locally heavy. Thundersnow

10530-462: The coding of GS, which is short for the French word grésil. Stones just larger than golf ball-sized are one of the most frequently reported hail sizes. Hailstones can grow to 15 centimetres (6 in) and weigh more than 500 grams (1 lb). In large hailstones, latent heat released by further freezing may melt the outer shell of the hailstone. The hailstone then may undergo 'wet growth', where

10665-586: 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 ;

10800-628: 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

10935-441: 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

11070-424: The deeper the clouds get, and the greater the precipitation rate becomes. In mountainous areas, heavy snowfall accumulates when air is forced to ascend the mountains and squeeze out precipitation along their windward slopes, which in cold conditions, falls in the form of snow. Because of the ruggedness of terrain, forecasting the location of heavy snowfall remains a significant challenge. The wet, or rainy, season

11205-403: The depth of the column of air being sampled and thus the vertical resolution of the data. In a “high mode,” the pulse length is increased, usually to 100 m or greater. The longer pulse length means that more energy is being transmitted for each sample, which improves the signal-to-noise ratio (SNR) of the data. Using a longer pulse length increases the depth of the sample volume and thus decreases

11340-531: The descending and generally warming, leeward side where a rain shadow is observed. In Hawaii , Mount Waiʻaleʻale , on the island of Kauai, is notable for its extreme rainfall, as it has the second-highest average annual rainfall on Earth, with 12,000 millimetres (460 in). Storm systems affect the state with heavy rains between October and March. Local climates vary considerably on each island due to their topography, divisible into windward ( Koʻolau ) and leeward ( Kona ) regions based upon location relative to

11475-548: The equator in Colombia are amongst the wettest places on Earth. North and south of this are regions of descending air that form subtropical ridges where precipitation is low; the land surface underneath these ridges is usually arid, and these regions make up most of the Earth's deserts. An exception to this rule is in Hawaii, where upslope flow due to the trade winds lead to one of the wettest locations on Earth. Otherwise,

11610-458: The first harvest, which occurs late in the wet season. Tropical cyclones, a source of very heavy rainfall, consist of large air masses several hundred miles across with low pressure at the centre and with winds blowing inward towards the centre in either a clockwise direction (southern hemisphere) or counterclockwise (northern hemisphere). Although cyclones can take an enormous toll in lives and personal property, they may be important factors in

11745-737: The flow of the Westerlies into the Rocky Mountains lead to the wettest, and at elevation snowiest, locations within North America. In Asia during the wet season, the flow of moist air into the Himalayas leads to some of the greatest rainfall amounts measured on Earth in northeast India. The standard way of measuring rainfall or snowfall is the standard rain gauge, which can be found in 10 cm (3.9 in) plastic and 20 cm (7.9 in) metal varieties. The inner cylinder

11880-579: The form of ice needles, rather than rain or snow. Convective rain , or showery precipitation, occurs from convective clouds, e.g. cumulonimbus or cumulus congestus . It falls as showers with rapidly changing intensity. Convective precipitation falls over a certain area for a relatively short time, as convective clouds have limited horizontal extent. Most precipitation in the tropics appears to be convective; however, it has been suggested that stratiform precipitation also occurs. Graupel and hail indicate convection. In mid-latitudes, convective precipitation

12015-400: The funnel needs to be removed before the event begins. For those looking to measure rainfall the most inexpensively, a can that is cylindrical with straight sides will act as a rain gauge if left out in the open, but its accuracy will depend on what ruler is used to measure the rain with. Any of the above rain gauges can be made at home, with enough know-how . When a precipitation measurement

12150-425: The gauge. Once the snowfall/ice is finished accumulating, or as 30 cm (12 in) is approached, one can either bring it inside to melt, or use lukewarm water to fill the inner cylinder with in order to melt the frozen precipitation in the outer cylinder, keeping track of the warm fluid added, which is subsequently subtracted from the overall total once all the ice/snow is melted. Other types of gauges include

12285-566: 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,

12420-463: The hailstones to the upper part of the cloud. The updraft dissipates and the hailstones fall down, back into the updraft, and are lifted again. Hail has a diameter of 5 millimetres (0.20 in) or more. Within METAR code, GR is used to indicate larger hail, of a diameter of at least 6.4 millimetres (0.25 in). GR is derived from the French word grêle. Smaller-sized hail, as well as snow pellets, use

12555-637: The higher bandwidth costs, Level II data is not available directly from the NWS. The NWS distributes this data freely to Amazon Web Services and several top-tier universities , which in turn distribute the data to private organizations. Download coordinates as: Download coordinates as: Precipitation (meteorology) In meteorology , precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle , rain , sleet , snow , ice pellets , graupel and hail . Precipitation occurs when

12690-487: The higher mountains. Windward sides face the east to northeast trade winds and receive much more rainfall; leeward sides are drier and sunnier, with less rain and less cloud cover. In South America, the Andes mountain range blocks Pacific moisture that arrives in that continent, resulting in a desertlike climate just downwind across western Argentina. The Sierra Nevada range creates the same effect in North America forming

12825-479: The ice crystals the crystals are able to grow to hundreds of micrometers in size at the expense of the water droplets. This process is known as the Wegener–Bergeron–Findeisen process . The corresponding depletion of water vapor causes the droplets to evaporate, meaning that the ice crystals grow at the droplets' expense. These large crystals are an efficient source of precipitation, since they fall through

12960-585: 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

13095-454: The liquid outer shell collects other smaller hailstones. The hailstone gains an ice layer and grows increasingly larger with each ascent. Once a hailstone becomes too heavy to be supported by the storm's updraft, it falls from the cloud. Snow crystals form when tiny supercooled cloud droplets (about 10 μm in diameter) freeze. Once a droplet has frozen, it grows in the supersaturated environment. Because water droplets are more numerous than

13230-476: 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

13365-571: 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

13500-459: 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

13635-520: 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

13770-424: The popular wedge gauge (the cheapest rain gauge and most fragile), the tipping bucket rain gauge , and the weighing rain gauge . The wedge and tipping bucket gauges have problems with snow. Attempts to compensate for snow/ice by warming the tipping bucket meet with limited success, since snow may sublimate if the gauge is kept much above freezing. Weighing gauges with antifreeze should do fine with snow, but again,

13905-490: The precipitation regimes of places they impact, as they may bring much-needed precipitation to otherwise dry regions. Areas in their path can receive a year's worth of rainfall from a tropical cyclone passage. On the large scale, the highest precipitation amounts outside topography fall in the tropics, closely tied to the Intertropical Convergence Zone , itself the ascending branch of the Hadley cell . Mountainous locales near

14040-581: The primary types are A, tropical; B, dry; C, mild mid-latitude; D, cold mid-latitude; and E, polar. The five primary classifications can be further divided into secondary classifications such as rain forest , monsoon , tropical savanna , humid subtropical , humid continental , oceanic climate , Mediterranean climate , steppe , subarctic climate , tundra , polar ice cap , and desert . Rain forests are characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1,750 and 2,000 mm (69 and 79 in). A tropical savanna

14175-406: 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

14310-465: 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

14445-430: 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

14580-493: The radial velocities with corrections for vertical motions. Pulse-Doppler radar wind profilers operate using electromagnetic (EM) signals to remotely sense winds aloft. The radar transmits an electromagnetic pulse along each of the antenna 's pointing directions. A UHF profiler includes subsystems to control the radar's transmitter, receiver, signal processing, and Radio Acoustic Sounding System (RASS), if provided, as well as data telemetry and remote control. The duration of

14715-501: 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

14850-432: 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

14985-502: 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 ,

15120-406: The remaining rainfall in the outer cylinder until all the fluid in the outer cylinder is gone, adding to the overall total until the outer cylinder is empty. These gauges are used in the winter by removing the funnel and inner cylinder and allowing snow and freezing rain to collect inside the outer cylinder. Some add anti-freeze to their gauge so they do not have to melt the snow or ice that falls into

15255-402: 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,

15390-413: The result at the surface. A temperature profile showing a warm layer above the ground is most likely to be found in advance of a warm front during the cold season, but can occasionally be found behind a passing cold front . Like other precipitation, hail forms in storm clouds when supercooled water droplets freeze on contact with condensation nuclei , such as dust or dirt. The storm's updraft blows

15525-438: The rising air motion of a large-scale flow of moist air across the mountain ridge, resulting in adiabatic cooling and condensation. In mountainous parts of the world subjected to relatively consistent winds (for example, the trade winds ), a more moist climate usually prevails on the windward side of a mountain than on the leeward or downwind side. Moisture is removed by orographic lift, leaving drier air (see katabatic wind ) on

15660-455: The standard for measuring precipitation, there are many areas in which their use is not feasible. This includes the vast expanses of ocean and remote land areas. In other cases, social, technical or administrative issues prevent the dissemination of gauge observations. As a result, the modern global record of precipitation largely depends on satellite observations. Satellite sensors work by remotely sensing precipitation—recording various parts of

15795-565: The strengths and minimize the weaknesses of the individual input data sets. The goal is to provide "best" estimates of precipitation on a uniform time/space grid, usually for as much of the globe as possible. In some cases the long-term homogeneity of the dataset is emphasized, which is the Climate Data Record standard. Alternatively, the High Resolution Precipitation Product aims to produce

15930-424: The surface, or ice. Mixtures of different types of precipitation, including types in different categories, can fall simultaneously. Liquid forms of precipitation include rain and drizzle. Rain or drizzle that freezes on contact within a subfreezing air mass is called "freezing rain" or "freezing drizzle". Frozen forms of precipitation include snow, ice needles , ice pellets , hail , and graupel . The dew point

16065-500: The transmission determines the length of the pulse emitted by the antenna, which in turn corresponds to the volume of air illuminated (in electrical terms) by the radar beam. Small amounts of the transmitted energy are scattered back (referred to as backscattering ) toward and received by the radar. Delays of fixed intervals are built into the data processing system so that the radar receives scattered energy from discrete altitudes, referred to as range gates. The Doppler frequency shift of

16200-437: The tropics—and becomes progressively less useful in areas where stratiform (layered) precipitation dominates, especially in mid- and high-latitude regions. The more-direct physical connection between hydrometeors and microwave channels gives the microwave estimates greater skill on short time and space scales than is true for IR. However, microwave sensors fly only on low Earth orbit satellites, and there are few enough of them that

16335-452: The vertical and the azimuth angle of each antenna are fixed when the system is set up. The vertical range of sodars is approximately 0.2 to 2 kilometers (km) and is a function of frequency, power output, atmospheric stability, turbulence , and, most importantly, the noise environment in which a sodar is operated. Operating frequencies range from less than 1000 Hz to over 4000 Hz, with power levels up to several hundred watts. Due to

16470-526: The vertical resolution in the data. The greater energy output of the high mode increases the maximum altitude to which the radar wind profiler can sample, but at the expense of coarser vertical resolution and an increase in the altitude at which the first winds are measured. When radar wind profilers are operated in multiple modes, the data are often combined into a single overlapping data set to simplify postprocessing and data validation procedures. Radar wind profilers may also have additional uses, for example in

16605-405: The water surface and the air above. Because of this temperature difference, warmth and moisture are transported upward, condensing into vertically oriented clouds (see satellite picture) which produce snow showers. The temperature decrease with height and cloud depth are directly affected by both the water temperature and the large-scale environment. The stronger the temperature decrease with height,

16740-447: The westerlies steer from west to east. Most summer rainfall occurs during thunderstorms and from occasional tropical cyclones. Humid subtropical climates lie on the east side continents, roughly between latitudes 20° and 40° degrees from the equator. An oceanic (or maritime) climate is typically found along the west coasts at the middle latitudes of all the world's continents, bordering cool oceans, as well as southeastern Australia, and

16875-444: The western US. Alternatively, a wind profiler may use sound waves to measure wind speed at various heights above the ground, and the thermodynamic structure of the lower layer of the atmosphere . These sodars can be divided in mono-static system using the same antenna for transmitting and receiving, and bi-static system using separate antennas. The difference between the two antenna systems determines whether atmospheric scattering

17010-414: The wet season. Animals have adaptation and survival strategies for the wetter regime. The previous dry season leads to food shortages into the wet season, as the crops have yet to mature. Developing countries have noted that their populations show seasonal weight fluctuations due to food shortages seen before the first harvest, which occurs late in the wet season. Wind profiler A wind profiler

17145-438: The worst storm expected in any single year. The term 1 in 100 year storm describes a rainfall event which is extremely rare and which will occur with a likelihood of only once in a century, so has a 1 percent likelihood in any given year. The rainfall will be extreme and flooding to be worse than a 1 in 10 year event. As with all probability events, it is possible though unlikely to have two "1 in 100 Year Storms" in

17280-500: 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

17415-476: 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

17550-593: 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 a list of upcoming improvements to

17685-616: 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

17820-520: 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

17955-589: 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

18090-651: 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,

18225-463: 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

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