One observation that is made when doing backyard meteorology is the precipitation rate. The general categories are light, moderate and heavy. A typical reference for the precipitation rate is the amount that falls in an hour. For example, a snowfall rate of 2 inches per hour and a rain rate of 0.25 inch per hour. A heavy precipitation rate can be mesmerizing. Heavy rain is defined as 0.30 inches or more falling within one hour. Heavy rain will tend to lower visibility and the rain will fall in sheets with large drops being observed. Heavy snow is defined using visibility. If the visibility is a quarter mile or less due to snow then it is reported as heavy snow. Heavy snow can accumulate at a rate of 0.5 inches per hour to several inches per hour depending on factors such as melting, snow density and snow intensity. Large numerous flakes with temperatures below freezing will tend to accumulate at several inches per hour. Below are several observations using precipitation rate: 1) The weather can go from no precipitation to huge heavy drops when a storm first moves in 2) Use a backyard rain gauge to measure rain intensity 3) Use a ruler and measure depth of snow at several locations in yard and find average for the amount of snow. Doing this in hourly intervals can be done to determine hourly accumulation rate. 4) Melt snow in a rain gauge to determine snow to liquid equivalent. For example, 10 inches of snow in gauge could melt down to 1 inch liquid equivalent. The density of the snow will determine the value. Dry fluffy snow will tend to take a greater accumulation to melt down to the same liquid equivalent as compared to wet dense snow. |