The Cloud Imagery (GOES IR) map layer displays infrared cloud imagery from NOAA/ National Environmental Satellite, Data, and Information Service's (NESDIS) Geostationary Satellites (GOES-East and GOES-West). The IR raster images are obtained from NESDIS' Satellite Services Division (SSD) in georeferenced Tagged-Image File Format (geoTIFF) and updated every 30 minutes on nowCOAST. The GOES images have an approximate horizontal resolution of 4 km (2.5 statute mile).

GOES satellites circle the Earth in a geosynchronous orbit, which means they orbit the equatorial plane of the Earth at a speed matching the Earth's rotation. This allows the satellites to hover continuously over one position on the surface. The geosynchronous plane is about 35,800 km (22,300 miles) above the Earth which is high enough to allow the satellites a full-disc view of the Earth. GOES-East also called GOES-12 is positioned at 75 deg W longitude and the equator. GOES-West or GOES-11 is located at 135 deg W and the equator. The two satellites operate cover an area from 20 deg W to 165 deg E.

The GOES IR Satellite images are derived from data from GOES' Imagers. The imager is a multichannel instrument that senses radiant energy and reflected solar energy from the Earth's surface and atmosphere.

The surface wind velocity (vector) analysis map layer displays the NOAA/National Weather Service's latest hourly gridded surface wind speed analysis from the NWS/National Centers for Environmental Prediction's (NCEP) Real-Time Mesoscale Analysis (RTMA) using colorized vectors.

The wind analysis is the wind velocity expected at 10m (~30ft) above ground level valid at that specified hour (i.e. a snapshot). The spatial resolution of the analysis is 5 km (3.1 miles). The wind speeds are in units of knots (1 knot = 1.15 miles per hour).

The wind velocity is indicated by colorized vectors which point in the direction where the wind is blowing towards. The speed forecast is indicated by both the color and size of the vector. The choice of color and size of the wind vectors were chosen to distinguish differences at low wind speeds, as well as to depict predictions of high winds associated with a Category 5 Hurricane. A legend is provided on the map to assist users in interpreting the wind velocity vectors as well as below. The legend includes ticks for both knots as well as miles per hour. The same color vectors are used in displaying the NDFD wind forecasts.

The RIDGE radar is a new and enhanced view of the NWS Doppler radar imagery that provides a mosaic of images across the Continental United States (CONUS) as well as Puerto Rico, Hawaii, Guam and Alaska with a 2 kilometer (1.25 mile) resolution.

A radar is an electronic instrument used for the detection and ranging of distant objects of such composition that they scatter or reflect energy, such as rain,snow or ice. This displays the base reflectivity radar. This a display of intensity (reflectivity) measured in dBZ (decibels of Z, where Z represents the energy reflected back to the radar).

Reflectivity is the amount of transmitted power returned to the radar receiver. Base Reflectivity images are available at several different elevation angles (tilts) of the antenna and are used to detect precipitation, evaluate storm structure, locate atmospheric boundaries and determine hail potential. Base reflectivity only shows reflectivity energy at a single elevation scan of the radar, whereas composite reflectivity images scans many levels and displays the highest reflected energy found at various elevation angles (AMS Glossary of Meteorology, 2000 and NOAA, 2004)

The Sea Surface Temperature (1/12 deg) analysis map layer displays the NOAA/ NWS/National Centers for Environmental Prediction's (NCEP) daily, high-resolution, real-time, global sea surface temperature analysis. The analysis uses the most recent 24-hours of in-situ and satellite-derived surface water temperature data to provide a global SST map. The analysis is frequently referred to as 'RTG_SST'.

The daily analysis in GRIB2 format is obtained once per day from a NCEP ftp server, encoded into a GIS-compatible format, and updated on nowCOAST at approximately 0400 UTC (11 PM EST). The SST analysis covers the world's ocean areas and also the Great Lakes with a 1/12 (~9 km) degree spatial resolution.

NCEP's daily SST (1/12 deg) analysis is generated using a two-dimensional variation interpolation scheme. The interpolation scheme uses the most recent 24-hours buoy and ship data, U.S. Navy's SEATEMP (SST) retrievals derived from AVHRR data from the NOAA-17 satellite, and SST's derived from satellite-observed sea-ice coverage. The first guess for the interpolation scheme is provided by the prior day's un-smoothed analysis with a one-day climate adjustment.

Significiant wave height is the average wave height of the highest 33% of all individual waves during a specified time sampling period. If a mariner was to observe the passage of 100 individual waves past a given point, the significant wave height would be the average height of the highest 33 waves. Significant wave height tends to be the height of the waves that is most readily observed by the human eye. NowCOAST displays significant wave height data from both buoys and ships. Wave observations at buoys are estimated from data from accelerometers or inclinometers on board during a 20 minute sampling period. Wave observations from ships are made by observers usually on the side of the ship form which the waves are coming. The quality of the wave observations from ships depend on the observer's training, size of the vessel, and the height at which the observation is taken.