METAR weather code reference for + (Heavy)
Placed before a weather phenomenon to indicate heavy intensity. For precipitation, heavy means the rate of fall is high and visibility is significantly reduced. For example, +RA means heavy rain and +SN means heavy snow. Heavy precipitation increases risks of reduced visibility, hydroplaning, and windshield obscuration.
Here are common ways + appears in real METAR observations:
+RA+SN+TSRAThese METAR codes are commonly seen alongside + or describe related weather phenomena:
Placed before a weather phenomenon to indicate light intensity. Light precipitation falls at a low rate and generally causes only minor reductions in visibility. For example, -RA means light rain and -SN means light snow. When no intensity modifier is present, moderate intensity is implied.
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.
A convective storm producing lightning and thunder. In METAR reports, TS indicates that thunder has been heard at the station within the observation period. Thunderstorms are among the most dangerous weather phenomena for aviation, bringing turbulence, wind shear, hail, heavy rain, and microbursts.