Subj : Wx Terms (N)(1)
To : All
From : Daryl Stout
Date : Thu Jun 15 2017 07:56 pm
N
North
Nacreous Clouds
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."
Nadir
The point on any given observer's celestial sphere diametrically opposite
of one's zenith.
NAM
The operational North Amercian Meso (NAM, formerly Eta) is run four times
per day (00,06,12,18Z), all cycles run to 84-h.
Nanotesla (nT)
A unit of magnetism equal to 10-9 tesla, equivalent to a gamma
(10-5 gauss).
NAO
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.
NAO Index
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.
National Ambient Air Quality Standards
In the United States, national standards for the ambient concentrations
in air of different air pollutants designed to protect human health and
welfare.
National Climatic Data Center
The agency that archives climatic data from the National Oceanic and
Atmospheric Administration, as well as other climatological organizations.
National Digital Forecast Database
(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.
National Fire Danger Rating System
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.
National Flood Summary
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.
National Hurricane Center
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.
National Hurricane Operations Plan
(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.
National Severe Storms Laboratory
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.
National Weather and Crop Summary
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.
Natural Control
In hydrologic terms, a stream gaging control which is natural to the
stream channel, in contrast to an artificial control structure by man.
Nautical Dawn
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.
Nautical Dusk
The time at which the sun is 12 degrees below the horizon in the
evening. At this time, objects are no longer distinguishable.
Nautical Mile
A unit of distance used in marine navigation and marine forecasts. It
is equal to 1.15 statue miles or 1852 meters. It is also the length of
1 minute of latitude.
Nautical Twilight
The time after civil twilight, when the brighter stars used for
celestial navigation have appeared and the horizon may still be seen.
It ends when the center of the sun is 12 degrees below the horizon,
and it is too difficult to perceive the horizon, preventing accurate
sighting of stars.
Navigation Methods
In hydrologic terms, there are three basic methods of providing and
managing inland waterways -
1) Run-of-the-River: no provision of upstream storage;
2) Slack-Water: locks and dams provide slack water or pools with
adequate depth for the draft of heavy barges and area to prevent
excessive velocities;
3) Canalization: in lieu of a series of dams on the river a canal with
locks adjoins the river.
NAVTEX
An international automated medium frequency (518 kHz) direct-printing
service for delivery of navigational and meteorological warnings and
forecasts, as well as urgent marine safety information to ships. It
was developed to provide a low-cost, simple, and automated means of
receiving this information aboard ships at sea within approximately
200 nautical miles of shore and is an element of the Global Maritime
Distress and Safety System (GMDSS). NAVTEX stations in the U.S. are
operated by the U.S. Coast Guard. There are no user fees associated
with receiving NAVTEX broadcasts. The International System uses the
frequency of 518 kHz worldwide and optional National Systems use
frequencies of 490 and 4205.5 kHz. Safety messages on 518 kHz have
to be in the English language worldwide but broadcasts on the 490 and
4209.5 kHz frequency can be in the local language.
NAVTEX Forecast
(NAV) - A National Weather Service marine forecast combining various
Coastal Waters and Offshore forecasts, optimized to accommodate
transmission via NAVTEX.
NBND
Northbound
NC
1. No change
2. North Carolina
NCAR
National Center for Atmospheric Research
NCCF
NOAA Central Computer Facility
NCDC
National Climatic Data Center
NCEP
National Centers for Environmental Prediction. A part of the National
Weather Service which provides nationwide computerized and manual
guidance to Warning and Forecast Offices concerning the forecast of
basic weather elements.
NDBC
National Data Buoy Center
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