The GWCC home page contains a two-panel graphic containing satellite and radar observations and a severe weather outlook courtesy of the NOAA NWS Storm Prediction Center. The following is a brief overview of these graphics (organized by column from top to bottom):
- GOES-16 (or GOES-East) and GOES-17 (or GOES-West) Geo-Color Satellite Imagery (upper panel) – This image, obtained by the GOES-16 and the GOES-17 (Geostationary Operational Environmental Satellite) imagers provides as close an approximation to daytime True Color imagery as is possible, and thus allows for an intuitive interpretation of meteorological and surface-based features. At night, instead of being dark like in other visible bands, an IR-based multispectral product is provided that differentiates between low liquid water clouds and higher ice clouds. A static city lights database derived from the VIIRS (Visible Infrared Imaging Radiometer Suite) Day Night Band is provided as the nighttime background for geo-referencing purposes. The 5-min imagery is projected per the satellite’s native orthographic projection. Note, that GOES-East satellite images on different web pages (or in different GWCC posts) may use different enhancement or “false color” image temperature scales. Colorized images, such as these, should always have their own color key included for geo-referencing purposes. The Geo-Color imagery regions included in the upper-panel of the home page include North America, Central America, South America, as well as much of the Central/Eastern Pacific and Atlantic Ocean basins. (credit: CIRA)
- Storm Prediction Center (SPC) convective outlook (lower panel) – SPC issues a wide array of severe weather and other thunderstorm-related guidance and outlook products. They also issue tornado and severe thunderstorm watches and fire weather outlooks. This image, which is often updated several times a day, shows expected thunderstorm and severe thunderstorm activity for “Day 1.” “Day 1” extends from the forecast time until the next 1200 GMT (Greenwich Mean Time or 8:00 a.m. E.D.T / 7:00 a.m. E.S.T. Favored areas for thunderstorm / severe thunderstorm activity are depicted as, “to the right of a line,” as shown by an arrow at the end of any line.
- Storm Prediction Center (SPC) current weather watch graphic (lower panel) – SPC issues a wide array of severe weather watches as situations require their issuance. This is the current graphic which shows any severe thunderstorm and tornado watches which are in effect over the contiguous United States at the present time. Please read about the purpose of our watches for further information.
- Storm Prediction Center (SPC) current mesoscale discussions graphic (lower panel) – SPC issues situational updates severe weather and winter weather-based updates for more extreme weather events across the contiguous U.S. in both real-time and shorter-term (1 to 4 hour) outlooks which are referred to as mesoscale discussions (MD’s). This is the current graphic showing any MD's which are in effect over the contiguous United States at the present time. Please read the description of the purpose of our MD's for further information.
- National radar composite image (lower panel) – This image brings together radar reflectivity data from some 100 plus dual-polarization radar sites throughout the contiguous 48 states. Radars measure how much energy atmospheric solids and liquids (hydrometeors such as snow, hail, and rain, as well as particles such as dense smoke and volcanic ash) reflect back to a radar site. The greater the reflectivity value (shown in dBz units), the greater the concentration of so-called “hydrometeors,” solids and other objects (e.g., birds, bats), the radar beam may intercept. The color scale ranges from blues and greens (the lowest reflectivities) to reds and purples (the highest reflectivities).