ReportFormatted output of a system providing specific information.
ReservoirA reservoir of an infectious agent, such as a virus, is any animal, person, plant, soil, substance—or combination of any of these — in which the…
Residence TimeThe average time spent in a reservoir by an individual atom or molecule. With respect to greenhouse gases, residence time usually refers to how long a…
Residual fuel oilHeavy fuel oil produced from the residue in the fractional distillation process rather than from the distilled fractions. No.
Residual Layerthe elevated portion of a convective boundary layer that remains after a stable boundary layer develops at the ground (usually in late afternoon or early…
Residual MoistureAtmospheric moisture which lingers over an area after the main weather system has departed.
resonanceThe state of a system in which an abnormally large vibration is produced in response to an external stimulus, occurring when the frequency of the stimulus…
RespirationThe process whereby living organisms convert organic matter to CO2, releasing energy and consuming O2.
Response TimeThe amount of time in which it will take a watershed to react to a given rainfall event.
Retrogression(or Retrograde Motion) - Movement of a weather system in a direction opposite to that of the basic flow in which it is embedded, usually referring to a…
Return FlowDrainage water from irrigated farmlands that re-enters the water system to be used further downstream.
Return StrokeAn electrical discharge that propagates upward along a lightning channel from the ground to the cloud.
Rex BlockA blocking pattern where there is an upper level high located directly north of a closed low.
RFCRiver Forecast Center. Centers that serve groups of Weather Service Forecast offices and Weather Forecast offices, in providing hydrologic guidance and is…
Ribbon LightningAppears to be a broad stream of fire. A succession of strokes, each blown a bit to the side of the previous strokes by wind, but striking so fast that all…
RidgeA line or wall of broken ice forced up by pressure. May be fresh or weathered.
Ridge IceIce piled haphazardly one piece over another in the form of ridges or walls.
Right AscensionThe celestial longitude of the sun. This value is 0 at the vernal equinox, 90 at the summer solstice, 180 at the autumnal equinox and 270 at the winter…
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.