METAR weather code reference for BL (Blowing)
Weather phenomenon raised by the wind to heights of 6 feet or more above the surface, significantly reducing visibility. Commonly used with snow (BLSN), dust (BLDU), and sand (BLSA). Blowing snow is especially hazardous because it can create whiteout conditions and make it impossible to distinguish the horizon or runway edges.
Here are common ways BL appears in real METAR observations:
BLSNBLDUBLSAThese METAR codes are commonly seen alongside BL or describe related weather phenomena:
Low drifting phenomenon that stays below eye level (generally below 6 feet). Commonly paired with snow (DRSN), dust (DRDU), or sand (DRSA). Drifting indicates the particles are being carried along the surface by wind but are not raised to significant heights. It differs from blowing (BL), which extends above eye level.
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.
Fine particles of earth or other matter raised from the ground by wind and suspended in the atmosphere. Widespread dust reduces visibility and is most commonly reported in arid regions. Dust events can cause significant restrictions to visibility and affect engine performance.
Larger particles of sand raised by the wind to moderate heights, reducing visibility. Sand is coarser than dust and typically stays closer to the surface. Blowing sand can cause engine damage, windshield abrasion, and significant visibility restrictions at airports in desert regions.