Now that North America is in the depths of winter, it is perhaps appropriate to take a closer look at the weather in Alaska, the northern Pacific, and western Canada. All of these regions have a major effect on the weather in North America. There are a number of fronts in this puzzle, but they will be a challenge to find. The key is in careful placement of isobars and attention to the weather patterns shown at various stations on the map. In the western United States, where terrain frequently disrupts horizontal consistency of the analysis, it is especially helpful to identify some of the stations and compare the conditions against climatological normals.
TIM VASQUEZ is a former Air Force forecaster and author of Digital Atmosphere, a weather-forecasting software program. He lives near Norman, Oklahoma, where he keeps busy as a weather consultant and software developer.