Jet Stream

Now a couple of other questions about the Jet Stream. When there is a large Low pressure area over the northwest I notice that the Jet folows about the bottom third of the Low, around the bottom then out to the north and east. Is the Jet attracted to the Low or does the Low slide down into the dip in the Jet?

I also noticed that when there is a large Low to the north of Utah and large High to the south that the Jet sneaks throught the gap between the two. As the Low and High come together the gap the Jet goes through narrows and all the winds are going basically East, does this pattern cause the Jet to narrow and speed up?

I noticed the other day a big High right over the West but I didn't see where the Jet was. Doest the Jet stay north of the big High pressure areas over the West?

What causes a split Jet Stream? Is there some kind of air wall that the Jet must go around?

Thanks,

Scott S.

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So many questions, so little time! Kidding, we've got all night! First of all we need to review the jet. The Jet Stream is a fast moving river of air high up in the atmosphere, the jet lives at about 20,000 feet and has wind speeds that can reach 300 mph!

The jet stream is what creates synoptic scale weather systems. So big things like Lows and Highs, not things like hurricanes or individual thunderstorms. As the jet stream dips and rises, that's where you find your lows and highs. So it's not so much that the jet is attracted to a low, it is responsible for the creation of that low.

Your example of a low to the north of Utah is hard to imagine, you'd have to show me a map of what you are talking about. There are a couple of branches of the jet too, so you can have a subtropical high over southern Utah and the Polar Jet bringing a low to the north. You can also have highs over lows and you get these weird things called blocks.

You are mentioning fast winds. Yes, when lows and highs get close together, they have a little party called the pressure gradient force. If you push them against eachother the wind increases. The jet stream has winds that can move in different direction, so you can have a low and a high getting close together with east winds or with north winds really, it could be anything, even south.

If you look at a weather map and you see those kinks in the jet stream, when the dip of a jet stream goes through, that's your trough and it can correspond with a front, definitely lots of wind going on. Check out the links to the right on basics about the jet. You have a lot of information you want to find out. If you want to pick up a copy or borrow one from the library, check out "The Weather Book" by Jack Williams. It has a ton of weather basics with great graphics to explain a lot of this without taking a course.

Split jets are another story and in the words of Mark Eubank "Never trust a split jet stream". The jet stream is like a river, and water hits things like objects and the flow changes around. The jet can split with objects such as changes in ocean temperatures or even land can interact and change the jet and cause it to split. When this happens, we get storms from both branches of the jet, this year the recent split jet has put a lot more storms in Southern Utah than in the North.

Answered by Meteorologist Dina Freedman and Dan Pope.