Weather is a dynamic process with conditions that can change throughout the day. It is important to gather all the available data, but you will also need to be paying attention to visual information such as clouds, wind-socks etc. These indicators may contradict data from the weather reports. On-site, visual data, almost always takes precedence over the weather data you’ve collected. There are a few circumstances where it doesn’t take precedence and will be covered in a later section.
There are two types of weather that you should be familiar with: frontal weather and local weather. Frontal weather occurs when two air masses like cold dry air from Canada, and warm, moist air from the Gulf of Mexico collide and cause a large scale storm that moves across the United States. This is what most weather reports focus on. What are the major weather systems in your area and what sort of weather will they produce? Are you under a low pressure system or a high pressure system? Where is the Jet Stream? Local weather relates to conditions like temperature, humidity, winds aloft, surface winds and topography. Puffy cumulous clouds over mountains are caused by local weather.
There are many types of clouds. Some can indicate good flying, while others can be dangerous or indicate dangerous conditions. Being able to read clouds properly will help you find areas of good lift, and safe conditions. Cloud formations may change rapidly during the day, so you should be constantly analyzing them for signs that the conditions are becoming too extreme, or deteriorating. The next few paragraphs will discuss frontal and local weather, their related clouds, and what they may mean for your flying.