Seattle Weather Radar and Cloud Cover

dBZ stands for decibels of Zwhere "Z" refers to the radar reflectivity factorwhich measures the strength of the radar signal reflected back to the radar from precipitation particles like rainsnowor hail.

dBZ is a logarithmic scale (i.e. exponential growth) that quantifies the amount of energy reflected by objects (typically raindropssnowflakesor other hydrometeors) in the atmosphere. The higher the dBZ valuethe stronger the reflected signalwhich typically means heavier precipitation; the contrasting colors on the radar maps above help visualize intensity and type.

Here's how dBZ values relate to the intensity of precipitation:

• 10-20 dBZ: Light rain or very light precipitation.
• 20-30 dBZ: Moderate rain or light snow.
• 30-40 dBZ: Heavy rain or moderate snow.
• 40-50 dBZ: Very heavy rainpotential for hail or strong thunderstorms.
• 50+ dBZ: Extreme precipitationoften associated with intense thunderstormstornadoesor hailstorms.