Moose Lake Star Gazette - Serving Carlton and Pine Counties Since 1895

By Kate Crowley
Moose Lake Star-Gazette 

What the jet stream has to do with you

Going Nature's Way

 

August 9, 2018



When it comes to the weather, we are currently the lucky ones, because we are in the area covered by a dip in the jet stream, keeping the very hot, humid weather to the south of us. Earlier in July, that same jet stream bulged northward and we sweltered through several days of high heat and high dew points, leading to cranky moods and very uncomfortable feelings whenever you stepped outside of an air-conditioned building or car.

The weather is constantly affecting our lives and giving us something to make small talk with strangers. In the summer time, when we Minnesotans long to be outside, our awareness of the weather and subsequently the jet stream is much more acute.

What is the jet stream, you ask? A dictionary definition goes like this: “a narrow, variable band of very strong, predominantly westerly air currents encircling the globe several miles above the earth.” This fairly simplistic definition belies the overwhelming influence this atmospheric highway. It is located at the level where jets cruise, hence the name. Before WWII, meteorologists were not able to confirm its existence until bombers experienced the intense head and tail winds, while flying at high altitudes, where winds will often reach 250 mph. This river of air is what sometimes makes our flights from the west coast to the east faster than the other way around.

The jet stream typically flows west to east and it is the undulations that bring changes in our weather, both in temperature and precipitation. There are three main belts over both hemispheres of the globe. They are just north and south of the equator and south or north of the two poles. When one of these bands of air bulges northward it is known as a ridge and if it goes southward, it’s called a trough. The streams are also often located near zones where there is a strong contrast in temperature. Until recently the northern band of this fast-moving air current would retreat in summer to Canada.

But two weeks ago, the country experienced a severe dip in that stream which led to weather disasters. It reached all the way from Canada to the Gulf of Mexico. Jeff Halverson, Capital Weather Gang’s severe weather expert said, “Even veteran meteorologists with decades of experience are astounded by the extreme nature of this jet stream pattern.”

Worse yet, the pattern became stuck in place. This led to multiple days of bad weather. There were tornadoes in Iowa and wind gusts of 60-80 mph from Nebraska to northern Arkansas, which led to the tragedy on the lake in Branson, where an amphibious vehicle capsized in the wind and waves. Moisture was pulled up the east coast causing widespread flash flooding in Pennsylvania, the Carolinas and New England. Baltimore got more than 15 inches of rain, a July record. Lifting northward on the western side of the country, it brought scorching heat from the Desert Southwest to Seattle. Death Valley, Calif. soared to a near record of 127 degrees.

These kinds of weird and disastrous weather events have not been limited to the United States. The Scandinavian countries and the Netherlands have seen several months’ long drought, which has led to fires in the Arctic Circle. In the Mediterranean, Greece experienced deadly fires near Athens, and Japan was inundated with rain and subsequent landslides.

The climate is definitely warming and changing. Scientists predicted over the past four to five decades that the warming would be greater in the Arctic regions (rising twice as fast as the global average) than the temperate zones. This has caused a lessening in the temperature difference between the two regions. Based on recent research, it appears that this is causing the jet stream to lose some of its strength and making it more prone to extreme fluctuations.

As CO2 levels continue to rise in the atmosphere, we can expect to see the current extreme events become more common, but no less destructive. We humans are at the mercy of the weather, but like it or not, we are also responsible for these changes.

With the rise of the internet and 24-hour news programming, we now can see what is happening around the world in real time. In Brazil, they are in the middle of winter. Last Saturday, a friend from the southern part of that country posted photos of the hail storms that hit his vineyard two days in a row. This is not normal for his area. I sent him a video made on Saturday in Birch Creek Township of a hailstorm that came through. Farmers and gardeners alike dread hail in the middle of the growing season. We are all connected — even if we live thousands of miles apart; the atmosphere and the jet stream surround us for better or worse.

 

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