The Ceiling and Visibility Analysis (CVA) product presents current and a recent history of ceiling and visibility conditions as determined by measurements from METAR (ASOS) stations and GOES satellites. The product is built on a 5 km grid and new images are produced every five minutes to incorporate updated METAR and satellite observations.

CVA's ceiling and visibility fields are derived through nearest-neighbor interpolation of METAR data. This interpolation process, in effect, 'stretches' limited-area METAR observations across the broader domain between stations while an accompanying process accounts for terrain effects on ceiling height. The resulting field helps to visualize the 'likely' conditions at range from METARS. However, the reliability of these fields generally degrades as distance from a METAR site increases. Thus, viewers should use practical judgment in considering the representativeness of the product at increased distances from a METAR site.

CVA's Flight Category field is derived from the underlying ceiling and visibility fields using the conventional category definitions given here.

In addition, CVA outlines regions where terrain obscuration is likely. These regions are determined as those where the cloud ceiling intersects rising terrain, resulting in a ceiling height near zero. Terrain obstruction information is summarized in the table below.