NCEP - National Centres for Environmental Prediction; the
modernized version of NMC.
Negative-tilt Trough - An upper level system which is tilted
to the west with increasing latitude (i.e., with an axis from
southeast to northwest). A negative-tilt trough often is a sign of a
developing or intensifying system.
NEXRAD - NEXt-Generation Weather RADar.
Technologically-advanced weather radar being deployed to replace
WSR-57 and WSR-74 units. NEXRAD is a high-resolution Doppler radar
with increased emphasis on automation, including use of algorithms
and automated volume scans. NEXRAD units are known as WSR-88D.
NGM - Nested Grid Model; one of the operational forecast
models run at NCEP. The NGM is run twice daily, with forecast output
out to 48 hours.
NMC - National Meteorological Centre, with headquarters near
Washington D.C.; now known as NCEP.
NOAA - National Oceanographic and Atmospheric Administration.
Nocturnal - Related to night-time, or occurring at night.
Nowcast - A short-term weather forecast, generally out to six
hours or less.
NSSFC - National Severe Storms Forecast Centre, in Kansas
City MO; now known as SPC.
NSSL - National Severe Storms Laboratory, in Norman OK.
(Sometimes pronounced NES-sel.)
NWP - Numerical Weather Prediction.
NWS - National Weather Service.