Sunday, January 12, 2020

A brain teaser for a rainy afternoon

We are having much warmer temperatures in north Georgia this January than usually occur. It is expected to reach 70°F (21°C) on Wednesday. We’ve also received a lot of rain lately, lots and lots of rain. It’s ultimately good for the grass, I know, but right now my back yard (British, garden) is saturated, spongy to walk on, downright unpleasant.

But enough about me and my problems. I want to ask you a question.

Something I either heard a meteorologist say several years ago or read in a newspaper or magazine article that was written by a meteorologist — I can’t remember which — Is now stuck in my brain. What I want to know from you is (a) do you think it is true? and (b) is there a difference?

Here it is:

When you hear a weather person say there’s a 60% chance of rain tomorrow, it doesn’t mean there is a 60% chance of rain in 100% of the viewing or listening area. It means there is a 100% chance of rain in 60% of the viewing or listening area.

Years ago my friend and workplace colleague Sanford J. Epstein, a 305-lb. Jew from Burlington, Vermont (as he often referred to himself, and who always wore a bright Kelly green suit to work on St. Patrick’s Day and changed his name tag to read “Sanford J. O’Epstein”) said “If there is a difference that makes no difference, then there is no difference.”

Is the “60% of 100% will have rain” versus “100% of 60% will have rain” puzzle easily dismissed simply by applying the Epstein Rule, or is there a true difference?

Inquiring minds want to know.

Think about it awhile; don’t jump to a conclusion prematurely.

The Bible says it rains on the just and on the unjust. I believe that. I also believe that it rains more on the just than on the unjust, because the unjust stole the just’s umbrella.

You heard it here first.


  1. The answer to your question is that the meteorologist is trying to make an educated guess without too many people saying he is wrong.

  2. I think it is a 60% chance of rain in 100% of the viewing area. But really I think he is just trying to cover himself in case it doesn't rain at all.

  3. I suspect that you also have to factor in the time that the forecast covers.

  4. My first thought is that mathematically it's the same, which means that from the perspective of any one precise location it's the same, but there is a difference in meaning between saying it's (a) definitely going to rain but they aren't sure where, and (b) there's a good chance it will rain and they are sure where.

  5. I live in the Pacific Northwest, so it's a moot point. It's going to rain. Period.

  6. I had to read your final paragraph twice because in the middle of a drought here I'm hoping it rains more on the just.
    Everything is becoming back to front.

  7. In our current drought I'm hoping the rain falls more on the just.

    Everything is becoming back to front

  8. I think there is a true difference. I don't think I always agree with your friend. We may not see or care about it, but it may matter in the grand scheme of things.
    And because I couldn't resist;
    Whether the weather be cold, Or whether the weather be hot, We'll weather the weather. Whatever the weather, Whether we like it or not!