Nimbostratus (Ns)

Abbreviated Ns. Principal type or cloud genus, stratiform, gray and often dark and thick enough to block the sun. Usually, nimbostratus produce rain, snow, sleet, etc. In most cases, the precipitation reaches the ground, but not always.

North Atlantic Deep Water (NADW)

Water mass located in the Atlantic between 3200 and 13000 feet (1000 and 4000 meters) of depth; it can be traced from there into most other oceans basins.


Commonly “nor’easter”. Particularly strong wind or gale, blowing from the northeast.


Description of current weather, and a very short-term (few hours) forecast.

Numerical model

Method of forecasting the weather through digital computations done by supercomputers.

Numerical weather prediction / Numerical forecasting

Forecast of meteorological variables through the integration of the governing equations of hydrodynamics in computer programs, subject to specified initial conditions.