Colour state other than clouds or low visibility (e.g. ice or other obstructions) then the word BLACK is written in full and placed immediately before the actual colour state (e.g. BLACKWHT). The colour state may be appended to a METAR report. A short period forecast called a "TREND" which covers the following two hours from the observation may also be added, often with reference to the colour state. The following criteria are used to determine the colour state: Colour state Colour states is a system used for quickly showing meteorological conditions. Meteorological colour states are determined by the relevant worst condition from
RAL colour standard RAL colour standard RAL is a colour matching system used in Europe that is created and administrated by the German RAL gGmbH (RAL non-profit LLC), which is a subsidiary of the German RAL Institute. In colloquial speech RAL refers to the RAL Classic system, mainly used for varnish and powder coating but nowadays there are reference panels for plastics as well. Approved RAL products are provided with a hologram as of early 2013 to make unauthorised versions difficult to produce. Imitations may show different hue and colour when observed under various light sources. In 1927 the German "Reichs-Ausschuß für Lieferbedingungen