Colour State
From Wikipedia, the free encyclopedia
Colour States are a system used for quickly showing meteorological conditions.
Meteorological colour states are determined by the relevant worst condition from the visibility and significant cloud height. In the USA and parts of Europe the lowest significant cloud layer is 5 oktas or more, in the United Kingdom it is three oktas or more. If visibility or cloud falls on a boundary e.g 1500 ft or 5000 m the colour state is in the higher value in this case WHT.
If an airfield runway is unusable for reasons other than cloud or 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.
[edit] Colour state criteria
| Colour state | BLU | WHT | GRN | YLO1 | YLO2 | AMB | RED |
|---|---|---|---|---|---|---|---|
| Cloud height in feet | 2500 | 1500 | 700 | 500 | 300 | 200 | <200 |
| Visibility in metres | 8000 | 5000 | 3700 | 2500 | 1600 | 800 |
