METAR weather code reference for UP (Unknown Precipitation)
Used by automated weather stations when precipitation is detected by sensors but the type cannot be determined. This typically occurs when the station lacks the sensors needed to differentiate between rain, snow, or other precipitation types. Pilots should use caution and seek additional weather information.
Here are common ways UP appears in real METAR observations:
UP-UP+UPThese METAR codes are commonly seen alongside UP or describe related weather phenomena:
Liquid precipitation in the form of water droplets greater than 0.5 mm in diameter. Rain is the most commonly reported precipitation type in METARs and can be combined with intensity modifiers (- for light, + for heavy) and descriptors like SH (showers) or FZ (freezing).
Frozen precipitation in the form of ice crystals, most often occurring as snowflakes. Snow significantly reduces visibility and is a primary concern for aircraft icing, runway contamination, and braking action. Often reported with intensity modifiers.
Very fine, uniformly dispersed liquid precipitation with droplets smaller than 0.5 mm in diameter. Drizzle typically falls from stratus clouds and indicates stable atmospheric conditions with low ceilings. Freezing drizzle (FZDZ) is especially hazardous for aircraft.