Thursday, September 3, 2015

60% Chance of Rain Today?

What does it mean when your meteorologist says 60% chance of rain?

It means that at any given point in our area there is a 60% chance of rain falling in the given time period.  In other words 6 times out of 10 given the weather set up you will get rain at your location.  This % approach is often used in the case of scattered convective precipitation like today.  Check out this image from early afternoon Thursday...much of the area is dry while it is pouring along the Sandusky/Seneca county line...


This brings me to a couple things I hear quite often.

"You said 30% chance of rain and it is POURING HERE!"
The % chance has nothing to do with how heavy the rain may be.

"You said 90% chance of rain and it only rained for 20 minutes.  BIG DEAL!"
The % chance has nothing to do with how long it might rain.

Hope this helps explain the POP (Probability Of Precipitation) in our forecasts.

Robert Shiels.