BUFFALO, N.Y. (WKBW) — Ever hear, "we have a 30% chance of rain today?"
Some think it's how much of an area will receive rain, as an example, only 30% of all of WNY will have rain. Or that it'll rain 30% of the time for that location.
What it actually means is:
The chance of precipitation is the percentage any one given location will receive rain within a certain amount of time.
For example, Buffalo has a 30% chance of rain today. This means there is a 30% chance Buffalo will have rain during the day. Typically, a given “day” or ‘night” time range is 12 hours, standard is between 7AM – 7PM for “day” and 7PM-7AM “night”.
The National Weather Service definition of probability of precipitation is:
The probability of precipitation (POP), is defined as the likelihood of occurrence (expressed as a percent) of a measurable amount of liquid precipitation (or the water equivalent of frozen precipitation) during a specified period of time at any given point in the forecast area. Measurable precipitation is equal to or greater than 0.01 inches. Unless specified otherwise, the time period is normally 12 hours. NWS forecasts use such categorical terms as occasional, intermittent, or periods of to describe a precipitation event that has a high probability of occurrence (80%+), but is expected to be of an "on and off" nature.
You may also see a percentage in an hourly graph, and it essentially means the same thing but over a shorter timeframe. If the graph is hourly for Buffalo, there will be a 30% chance this location will receive rain during this hour.
