The northern Polar jet stream is said to follow the sun as it slowly migrates northward as that hemisphere warms, and southward again as it cools. The width of a jet stream is typically a few hundred kilometres or miles and its vertical thickness often less than five kilometres (10feet). In the winter, the jet core is generally closer to the 300mb level, since the air is more cold and dense in the vicinity of the jet stream during the cool season. The 200mb chart is used during the warmer seasons. The jet stream is a current of fast moving air found in the upper levels of the atmosphere.
This rapid current is typically thousands of kilometers long, a few hundred kilometers wide, and only a few kilometers thick.
These slim strips of strong winds have a huge influence on climate, as they can push air masses around and affect weather patterns. Jet streams are like rivers of wind high above in the atmosphere. Contains maps of where the jet stream is now, and where forecasters think it will be in the future. The National Weather Service understands the critical value of fast, accurate weather information. We know that information is power - the power to save your life or the lives of your loved ones.