Sunday, 05 November, 2000
20% Chance of Rain?
Yet another rainy day here in central Texas. I remember reading that this area gets an average of 35 inches of rain per year, but I didn't realize that I'd get half of that in just a few weeks. Just goes to show that you need to look at more than just the annual averages before you make a judgment on the climate. If you're interested in historical weather data, one of the best places to start is the National Weather Service's pages. This site displays a map of the United States, with all of the NWS offices highlighted. From here, click on an office to go to their web page, from which you can locate local climate information.
Speaking of weather, I'm concerned that maybe our local TV weatherman doesn't know what he's talking about. On several occasions I've heard him describe a 20% chance of rain by saying "That means that 20% of our listening area will get rain today." That's just absurd. What it really means is that there's a 20% chance that some place in the area (possibly the entire area) covered by the forecast will get measurable rain. See "What forecast terms mean" on this page for more information. That's a huge difference. The percentages are based on current observations and comparisons with historical data.
USA Today has an excellent weather page. I'm kind of surprised that this web site is associated with that terrible newspaper. The Ask Jack section answers people's questions about weather, and the Topic Index has entries for a wide range of topics.