Weather on the Web

Weather by Len Oddy

Ottawa Power & Sail Squadron newsletter April 2000

All boaters are affected by the weather - for better or for worse. It doesn't matter if you are going out for a few hours or a few days, you should know what weather to expect. The longer the period the greater the need for weather maps, especially the Surface Weather Map, also called the Systems Chart by some. The Power Squadron Weather Course won't teach you to forecast the weather, but it will help you to interpret the forecast when it goes wrong by teaching WHY the weather does what it does. You can then turn a "busf' forecast into a useable one.

The World Wide Web is a wonderful source of the kind of infon-nation you need to understand the WHYS of the weather. There are literally hundreds of weather sites on the Web. Most provide access to a variety of weather maps which give a view of conditions over a wide area anywhere in the world. Most give the Current Surface Map. Some give time-lapse or anitnated sequences (also called loops) of changes over several hours. Some are designed for special purposes such as aviation or navigation. On some sites a whole library of questions and answers is available on a variety of weather topics. On others the charts available are the technically more advanced charts that the meteorologists themselves use. And on some, unhappily, the main motivation seems to be to sell you their services or products, and very little is free.

Weather forecasts on the radio, on the other hand, usually give only the forecast itself with little or no description of the physical processes that are the cause of the weather. In addition, the information is read so fast it is often very difficult to take in and remember the details. On television and the Web the information is in written fon-n and is backed-up by maps and diagrams, making it easier to understand and remember.

For the boater who wants to understand more than simply the bare forecast, the following web sites are some that I find most useful. You'll soon find your favorites too. This is one of the best sites for variety of chart information. Although it tends to emphasize U.S. locations there is usually over-lap into Canada as far north as James Bay. Use the tool bar to click on Surface Maps, Upper Level Maps, Radar Images etc. Surface isobars are computer-produced and may appear a bit rough. Many of the charts are working weather charts. This is also "",and has the same information as The Weather Channel on television. Drag down to the Current Surface Map and enlarge it for an excellent map of surface isobars, fronts and precipitation. Local regional enlargements also available. Use left-hand menu for more options. Use "How Weather Works" for answers to questions. This is their home page. Click on "Weather" and then "weather maps" for wide selection of maps from Africa to South America. North America and Regional Images are especially good - wait for the animation to load - its worth it! Excellent for weather information of all sorts. First rate verbal discussions of forecasts by country and region but no surface maps. Left hand menu for satellite and radar images. Excellent weather Questions and Answers in "Ask Jack". "Weather Library" is a good source of information on many weather topics. This is the source for all U.S. weather information and many of the charts are working charts for the forecasters. Click on Animated Graphics Version, then on whichever small map takes your interest to enlarge, then on 6hr animation. Return to MIN page, then click on Graphics icon below the small maps and drag down page to whatever catches your fancy. Move further down for HPC Forecast Graphics, click on Sea Level Pressure for surface weather maps. Explore!

This is just a sample of what is out there. By digging into the ".gov"site you can find many more weather sites addresses. Good weather and good sailing!