Precipitation in a weather report refers to water that falls from the sky in the form of rain, snow, sleet, hail, or other forms of atmospheric moisture. Precipitation is an important factor in weather forecasting as it can tell us about other things going on in the atmosphere and what we might need to do, such as taking an umbrella or getting ready to build a snowman. The probability of precipitation forecast is one of the least understood elements of the weather forecast. The probability of precipitation is expressed as a percentage and is a statistical probability of 0.01 inches or more of precipitation at a given area in the given forecast area in the time period specified. The probability of precipitation does not mean that a certain percentage of the area will be covered by precipitation at a given time or that you will be seeing precipitation for a certain percentage of the time in the given forecast area. Meteorologists calculate the probability of precipitation based on two factors: the likelihood of occurrence of precipitation and the coverage area of the precipitation. The higher the percentage, the greater the chance of precipitation occurring in the forecast area and time.