North
- Browse Related Terms: Alaska Current, Aleutian Current, Antilles Current, Azores Current, Hague Line, N, NC, PNA, Rex Block, Typhoon Season
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Clouds of unknown composition that have a soft, pearly luster and that form at altitudes about 25 to 30 km above the Earth's surface. They are also called "mother-of-the-pearl clouds."
- Browse Related Terms: Air, Climate System, Conjugate Points, Downwelling Radiation, Equinox, Free Atmosphere, Ground Heat Flux, Latent Heat Flux, Lightning Discharge, Mesoclimate, Nacreous Clouds, Net All-Wave Radiation, Noctilucent Clouds, Radiational Cooling, Rain, Rotation, Sensible Heat Flux, Surface Energy Budget, Surface-based Convection, Visible Satellite Imagery
The point on any given observer's celestial sphere diametrically opposite of one's zenith.
- Browse Related Terms: AMOS, Blowing, Cooperative Observer, GoMoos, Hourly Precipitation Data (HPD), Isochrone, Mesonet, Meteogram, Nadir, OBS, parameter, Rawinsonde Observation, Reconnaissance Code, report, Station Model, Upper Level
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The operational North American Meso (NAM, formerly Eta) is run four times per day (00,06,12,18Z), all cycles run to 84-h.
- Browse Related Terms: Climate Diagnostics Center, Coordinated Universal Time (UTC), GMT, Intermediate Synoptic Times, Main Synoptic Times, MAINT, NAM, Standard Synoptic Times, Universal Time (UT), UTC, Z, Zulu (Z) Time
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A unit of magnetism equal to 10-9 tesla, equivalent to a gamma (10-5 gauss).
- Browse Related Terms: Astronomical Unit, Emerging Flux Region (EFR), Filament, Gamma, Geophysics, Interplanetary Magnetic Field, Leader Spot, Magnetogram, Magnetosphere, MEGG, Mount Wilson Magnetic Classifications, Nanotesla (nT), Neutral Line, PDMT, Plage, Sector Boundary, Sferic, Solar Wind, sunspot, Sunspot Group Classification, Two-Ribbon Flare
North Atlantic Oscillation - the NAO is a large-scale fluctuation in atmospheric pressure between the subtropical high pressure system located near the Azores in the Atlantic Ocean and the sub-polar low pressure system near Iceland and is quantified in the NAO Index. The surface pressure drives surface winds and wintertime storms from west to east across the North Atlantic affecting climate from New England to western Europe as far eastward as central Siberia and eastern Mediterranean and southward to West Africa.
- Browse Related Terms: EWD, Kelvin Waves, NAO, North Atlantic Oscillation, Oceanography, Return Flow, Thermocline, Tropical Cyclone, W
This index measures the anomalies in sea level pressure between the Icelandic low pressure system and the Azores high pressure system in the North Atlantic Ocean.
When the NAO is in its is positive phase (+NAO), the northeastern United States sees an increase in temperature and a decrease in snow days; the central US has increased precipitation, the North Sea has an increase in storms; and Norway along with Northern Europe has warmer temperatures and increased precipitation.
When the NAO is in its negative phase (-NAO), the Tropical Atlantic and Gulf coast have increased number of strong hurricanes; northern Europe is drier, and Turkey along with other Mediterranean countries has increased precipitation.
- Browse Related Terms: AO, Arctic Oscillation, El Niño, INTSFY, La Niña, NAO Index, NEG, Negative-tilt Trough, NW, Oscillation, Pacific Decadal Oscillation, PDO, Positive-tilt Trough, Southern Oscillation
In the United States, national standards for the ambient concentrations in air of different air pollutants designed to protect human health and welfare.
- Browse Related Terms: Air Quality Model, Class I Areas, DTRT, National Ambient Air Quality Standards, Nonattainment area, Prevention of Significant Deterioration, Primary Ambient Air Quality Standards, Secondary Ambient Air Quality Standards
The agency that archives climatic data from the National Oceanic and Atmospheric Administration, as well as other climatological organizations.
- Browse Related Terms: AFWA, Client Agency, FEMA, LCD (Local Climatological Data), National Climatic Data Center, NCAR, NCDC, NDBC, NOAA, NWS, OEODM, U.S. Geological Survey, WC/ATWC
(NDFD)- The National Weather Service's NDFD provides access to gridded forecasts of sensible weather elements (e.g., wind, wave height) through the National Digital Forecast Database (NDFD). NDFD contains a seamless mosaic of digital forecasts from NWS field offices working in collaboration with the National Centers for Environmental Prediction (NCEP). The database is made available to all customers and partners from the public, private and academic sectors. Those customers and partners may use this data to create a wide range of text, graphic, gridded and image products of their own.
- Browse Related Terms: Action Stage, ADDS, BAPSU, County Warning and Forecast Area, County Warning Area, HSA (Hydrologic Service Area), Hydrologic Service Area, National Digital Forecast Database, NCEP, NDFD, NWSO, OH, Post-storm Report, RFC, River Forecast Center, SKYWARN, Watch Redefining Statement, WSFO
A uniform fire danger rating system used in the United States that focuses on the environmental factors that impact the moisture content of fuels. Fire danger is rated daily over large administrative areas, such as national forests.
- Browse Related Terms: EPA, HMD, National Fire Danger Rating System, SOLN, SOLNS, Ultraviolet Index, UV Index
This NWS daily product (abbreviated FLN) contains nationwide information on current flood conditions. It is issued by the Hydrometeorological Information Center of the Office of Hydrology.
- Browse Related Terms: CIO, Data Point, Forecast Issuance Stage, National Flood Summary, National Hurricane Operations Plan, NHOP, PMO, River Flood Warning, River Forecast, RVF, SOO, Special Tropical Disturbance Statement, Tropical Cyclone Position Estimate
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A fixed reference adopted as a standard geodetic datum for elevations determined by leveling. The datum was derived for surveys from a general adjustment of the first-order leveling nets of both the United States and Canada. In the adjustment, mean sea level was held fixed as observed at 21 tide stations in the United States and 5 in Canada. The year indicates the time of the general adjustment. A synonym for Sea-level Datum of 1929. The geodetic datum is fixed and does not take into account the changing stands of sea level. Because there are many variables affecting sea level, and because the geodetic datum represents a best fit over a broad area, the relationship between the geodetic datum and local mean sea level is not consistent from one location to another in either time or space. For this reason, the National Geodetic Vertical Datum should not be confused with mean sea level.
- Browse Related Terms: Advisory, Best Track, center, Hurricane Local Statement, Inundation, National Geodetic Vertical Datum (NGVD) of 1929 [NGVD 1929], Post-storm Report, Preliminary Report, Present Movement, Relocated, Saffir-Simpson Hurricane Wind Scale, Storm Surge, Storm Tide
One of three branches of the Tropical Prediction Center (TPC). This center maintains a continuous watch on tropical cyclones over the Atlantic, Caribbean, Gulf of Mexico, and the Eastern Pacific from 15 May through November 30. The Center prepares and distributes hurricane watches and warnings for the general public, and also prepares and distributes marine and military advisories for other users. During the "off-season" NHC provides training for U.S. emergency managers and representatives from many other countries that are affected by tropical cyclones. NHC also conducts applied research to evaluate and improve hurricane forecasting techniques, and is involved in public awareness programs.
- Browse Related Terms: Air Transportable Mobile Unit, IPV, National Hurricane Center, NHC, Preliminary Report, TAFB, Tropical Analysis and Forecast Branch, Tropical Weather Discussion
(NHOP) - The NHOP is issued annually by the Federal Coordinator for Meteorological Services and Supporting Research. It documents interdepartmental agreements relating to tropical cyclone observing, warning, and forecasting services. National Hurricane Center (NHC), Central Pacific Hurricane Center (CPHC), and the JTWC serve as the principal offices in coordinating the day-to-day activities of the NWS in support of the Plan in their region of responsibility.
- Browse Related Terms: CIO, Data Point, Forecast Issuance Stage, National Flood Summary, National Hurricane Operations Plan, NHOP, PMO, River Flood Warning, River Forecast, RVF, SOO, Special Tropical Disturbance Statement, Tropical Cyclone Position Estimate
This is one of NOAA's internationally known Environmental Research Laboratories, leading the way in investigations of all aspects of severe weather. Headquartered in Norman OK with staff in Colorado, Nevada, Washington, Utah, and Wisconsin, the people of NSSL, in partnership with the National Weather Service, are dedicated to improving severe weather warnings and forecasts in order to save lives and reduce property damage.
- Browse Related Terms: Doc, Excessive Heat Outlook, Experimental Product, ITWAS, K, National Severe Storms Laboratory, NSSL, Operational Products, Residual Moisture, Smoke, track
A product of the National Agricultural Statistics Service, Agricultural Statistics Board, and U.S. Department of Agriculture. It contains weekly national agricultural weather summaries, including the weather's effect on crops; summaries and farm progress for 44 states and New England area.
- Browse Related Terms: AFD, Area Forecast Discussion, GLF, GLS, Great Lakes Marine Forecast (MAFOR), Great Lakes Storm Summary, Great Lakes Weather Broadcast, LAWEB, MAFOR, Marine Weather Statement, National Weather and Crop Summary, Nearshore Forecast, Open Lakes Forecast, Tropical Weather Summary
In hydrologic terms, a stream gaging control which is natural to the stream channel, in contrast to an artificial control structure by man.
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The time at which the sun is 12 degrees below the horizon in the morning. Nautical dawn is defined as that time at which there is just enough sunlight for objects to be distiguishable.
- Browse Related Terms: Astronomical Dawn, Astronomical Dusk, Civil Dawn, Civil Dusk, Dawn, Dusk, EVE, Horizon, LGT, MRNG, Nautical Dawn, Nautical Dusk, Sunrise, Sunset
The time at which the sun is 12 degrees below the horizon in the evening. At this time, objects are no longer distinguishable.
- Browse Related Terms: Astronomical Dawn, Astronomical Dusk, Civil Dawn, Civil Dusk, Dawn, Dusk, EVE, Horizon, LGT, MRNG, Nautical Dawn, Nautical Dusk, Sunrise, Sunset