FORT WAYNE, Ind. (WFFT) — It is probably one of the most misunderstood terms in weather, the chance of precipitation.
Those percentages appear frequently in the 7-day and hourly planners, but it is not completely understood what the numbers mean.
Recently, a TikTok user shared her confusion and it sparked a conversation.
For instance, some people might think that a 60% chance of rain means that 60% of their area, such as Fort Wayne, will see rain.
Others might think that a 60% chance of rain means that it will rain 60% of the day.
Let’s start with terminology.
POP means the probability of precipitation.
It’s a mathematical equation that is used to forecast the coverage of rain.
Chance of rain = Confidence X Area
Confidence meaning that forecaster is confident the precipitation will occur somewhere in the forecast area.
Area represents the locations that will receive measurable precipitation.
The WFFT viewing area covers approximately 20 counties that spans across two states.
The POP that we always talk about is for the viewing area only.
Using the equation above, I am 100% sure that 60% of our forecast area will receive at least 0.01” of rain.
So the forecast for the day calls for a 60% chance of rain.
If you move outside of the WFFT area, then that percentage will change.
It is important to note that the percentage does not factor in how much rain will fall and the intensity of it.
Since PoPs can be tricky, you might hear me say “few” or “scattered” instead.
If we are looking at 10% to 30% chance of showers during the day I will say "isolated".
From 40% to 60%, I will usually say the activity is "scattered" and anything above 70% is "likely" or "widespread".
Just remember, at the end of the day, the WFFT viewing area covers more than just one location.