What does the term Zonal Flow mean?
You may have heard meteorologists use the term “zonal flow”. What does that mean? It means that the wind flow in the upper atmosphere will be predominately from west to east across most of the United States with no real dips in the jet stream. This usually means that there will not be any real intense low pressure systems developing and temperatures will not be too extreme for the most part in our part of the country. Depending on the time of year, it can mean that we will see rapid day to day changes in the weather conditions as weather systems move faster west to east during these periods. In the colder season, the Arctic or Polar air masses are “trapped” in Canada and the deep moisture from the Gulf of Mexico cannot move northward very far. So any rainfall (or snowfall) that does occur is usually lighter during these periods. However, it still could be quite stormy in some parts of the country during a zonal flow period, but for the most part, weather systems tend to be weaker.