Right Entrance RegionUsed interchangably with Right Rear Quadrant; the area upstream from and to the right of an upper-level jet max (as would be viewed looking along the…
Right MoverA thunderstorm that moves appreciably to the right relative to the main steering winds and to other nearby thunderstorms.
Right Rear Quadrant(Abbrev. RRQ) - Used interchangably with Right Entrance Region; the area upstream from and to the right of an upper-level jet max (as would be viewed…
RimeRime A white or milky and opaque granular deposit of ice formed by the rapid freezing of super-cooled water drops as they impinge upon an exposed object.
Rime IceAn opaque coating of tiny, white, granular ice particles caused by the rapid freezing of supercooled water droplets on impact with an object.
Riometer(Relative Ionospheric Opacity meter). A specially designed radio receiver for continuous monitoring of cosmic noise.
Rip CurrentA relatively small-scale surf-zone current moving away from the beach. Rip currents form as waves disperse along the beach causing water to become trapped…
Riparian ZoneThe transition zone between the water and the upland zone. Can be identified by specific types of plants and soils.
River BasinThe land area surrounding one river from its headwaters to its mouth. The area drained by a river and its tributaries.
River Flood StatementThis product is used by the local National Weather Service Forecast Office (NWFO) to update and expand the information in the River Flood Warning.
River Flood WarningThis is product is issued by the local National Weather Service Forecast Office (NWFO) when forecast points (those that have formal gaging sites and…
River FloodingThe rise of a river to an elevation such that the river overflows its natural banks causing or threatening damage.
River ForecastAn internal product issued by RFCs to other NWS offices. An RVF contains stage and/ or flow forecasts for specific locations based on existing, and…
River Forecast CenterCenters that serve groups of Weather Service Forecast offices and Weather Forecast offices, in providing hydrologic guidance and is the first echelon…
River Gage DatumThe arbitrary zero datum elevation which all stage measurements are made from.
River Ice StatementA public product issued by the RFC containing narrative and numeric information on river ice conditions.
River Observing StationAn established location along a river designated for observing and measuring properties of the river.
River Recreation StatementA statement released by the NWS to inform river users of current and forecast river and lake conditions.
River StatementA NWS product issued to communicate notable hydrologic conditions which do not involve flooding, i.e., within river bank rises, minor ice jams, etc.
River SystemAll of the streams and channels draining a river basin.
RocketsondeA type of radiosonde that is shot into the atmosphere by a rocket, allowing it to collect data during its parachute descent from a higher position in the…
Rockfill DamAn embankment dam in which more than 50 percent of the total volume is comprised of compacted or dumped cobbles, boulders, rock fragments, or quarried…
Rogue WaveCommonly used term by mariners of a wave of an unexpected wave of much greater height or steepness than other waves in the prevailing sea or swell system.
Roll CloudA low, horizontal tube-shaped arcus cloud associated with a thunderstorm gust front (or sometimes with a cold front).
Rolled Filled DamAn embankment dam of earth or rock in which the material is placed in layers and compacted by using rollers or rolling equipment. Same as Rockfill dam.
Rope(Also "Rope Funnel") - a narrow, often contorted condensation funnel usually associated with the decaying stage of a tornado. See rope stage.
Rope CloudIn satellite meteorology, a narrow, rope-like band of clouds sometimes seen on satellite images along a front or other boundary.
Rope StageThe dissipating stage of a tornado, characterized by thinning and shrinking of the condensation funnel into a rope (or rope funnel).
ROSARemote Observing System Automation. A type of automated data transmitter used by NWS Cooperative Program observers.
Rossby WavesA series of troughs and ridges on quasi-horizontal surfaces in the major belt of upper tropospheric westerlies.
RotationThe number of years allotted to establish and grow a forest stand to maturity.
Rotor CloudA turbulent altocumulus cloud formation found in the lee of some mountain barriers when winds cross the barrier at high speed.
Rotten IceIce in an advanced stage of disintegration.
Rough SeasSea conditions associated with regionally defined wind thresholds over bays, inlets, harbors, inland waters, and estuaries where larger waves are forming…
RoutingThe methods of predicting the attenuation of a flood wave as it moves down the course of a river.
RUCRapid Update Cycle model, a numerical model run by NCEP that focuses on short-term forecasts out to 12 hours.
RunoffThe water that flows off the surface of the land, ultimately into our streams and water bodies, without being absorbed into the soil.
Runway Visual RangeThe maximum distance at which the runway, or the specified lights or markers delineating it, can be seen from a position above a specified point on its…
RVARiver Summary, a NWS summary of river and/or crest stages for selected forecast points along the river.
RVFRiver Forecast. An internal product issued by RFCs to other NWS offices. An RVF contains stage and/ or flow forecasts for specific locations based on…
RVR1. Runway Visual Range - the maximum distance at which the runway, or the specified lights or markers delineating it, can be seen from a position above a…
RVS1. Abbreviation for "revise" 2. River Statement, a product issued to communicate notable hydrologic conditions which do not involve flooding, i.e.
S-Band RadarThese were in use as network radars in the National Weather Service prior to the installation of the WSR 88-D radars.
S/WShortwave - a disturbance in the mid or upper part of the atmosphere which induces upward motion ahead of it.
S/WVShortwave - a disturbance in the mid or upper part of the atmosphere which induces upward motion ahead of it.
SafetyNETInmarsat-C SafetyNET is an internationally adopted, automated satellite system for promulgating weather forecasts and warnings, marine navigational…
Saffir-Simpson Hurricane Wind ScaleThe Saffir-Simpson Hurricane Wind Scale is a 1 to 5 categorization based on the hurricane's intensity at the indicated time.
Saffir-Simpson ScaleThis scale was developed in an effort to estimate the possible damage a hurricane's sustained winds and storm surge could do to a coastal area.
Salinity (SAL)In oceanography, conductivity is measured and converted to salinity by a known functional relationship between the measured electrical conductivity of…
SAME(Specific Area Message Encoding) - A tone alert system which allows NOAA Weather Radio receivers equipped with the SAME feature to sound an alert for only…
SandstormParticles of sand carried aloft by strong wind. The sand particles are mostly confined to the lowest ten feet, and rarely rise more than fifty feet above…
Santa Ana WindIn southern California, a weather condition in which strong, hot, dust-bearing winds descend to the Pacific Coast around Los Angeles from inland desert…
SastrugiRidges of snow formed on a snow field by the action of the wind.
Satellite Hydrology ProgramA NOHRSC program that uses satellite data to generate areal extent of snow cover data over large areas of the western United States.
SaturationSaturation The condition in which the partial pressure of any fluid constituent (water in the atmospheric air) is equal to its maximum possible partial…
Saturation Vapor PressureThe vapor pressure of a system, at a given temperature, wherein the vapor of a substance is in equilibrium with a plane surface of that substance's pure…
SavannaA flat grassland of tropical and subtropical regions usually having distinct periods of dry and wet weather.
SAWRSSupplementary Aviation Reporting Station - the SAWRS program addresses the concerns of users who depend on weather observations for air operations.
SBCAPESurface Based CAPE; CAPE calculated using a Surface based parcel.
ScaleRatio of map distance to Earth distance. Thus, in a 1:24,000 scale map, one centimeter, inch, or foot equals 24,000 centimeters, inches, or feet on the…
ScatteredWhen used to describe precipitation (for example: "scattered showers") - Area coverage of convective weather affecting 30 percent to 50 percent of a…
ScatteringThe process in which a beam of light is diffused or deflected by collisions with particles suspended in the atmosphere.
Science BoardAn ACRF group made up of the ARM Science Team Executive Committee working group science chairs and climate research community appointees, that ensures…
Science Team Executive Committee (STEC)(STEC)The committee that provides recommendations, prioritization, coordination of activities, and program vision to the U.S.
SCUDSmall, ragged, low cloud fragments that are unattached to a larger cloud base and often seen with and behind cold fronts and thunderstorm gust fronts.