Less probable than half is still possible

Erica once asked me what probability of rain given in the weather forecast would prompt me to carry an umbrella. "40%" I said. She couldn't get why. "50% is more logical," she told me. It depends on what your tolerance for getting wet is. Anything greater than zero is most logical, but terribly inconvenient. I felt like I'd given a wrong answer to "What's your favorite color?"

The reason why I gave the answer I did is exemplified by today's weather. I just walked through a drizzle on my way to work this morning, and weather.com still gives it a mere 40% chance of raining today.