Polar Vortex Summer Edition-Explained

It’s been really cool overall these past several weeks in this area on average.

A needed relief and change to the normality of deathly humidity and scorching hot temperatures that usually dominate this area’s summer climate. The reason simplistically of why this is is due to the fact of dynamic atmospheric motion that has brought the cooler pockets of air down from Northwestern Canada to the Lower Midwest and Mid Atlantic regions. In return though, the upper Midwest and Northeast is seeing a higher influx of severe storms while the West is scorching with record highs and worsening the already costly drought in places like California and Arizona.

All of this can be explained by a deep trough in the jet stream that was first spotted back in early June; though it has taken full effect within the past couple of weeks. Why did the dip take place in the first place? 

The Dark Blue is below average and the Orange and Red is above average (NOAA)

Many have pointed to below average temperatures this summer as a direct resultant to a well-below average winter. Peak ice coverage for the Great Lakes was in Mid-March, which is much later than it normally has been in past years. It was also much higher too with almost 94 percent of the Great Lakes being frozen over. The slow melt causes cooler temperature to settle within the regions surrounding them.

Peak Ice Extension for Winter 2014

Another reason though for the cool down this summer is climate change and the warming of the Arctic region. The persistent high pressure systems in place and large temperature swings are all within the climate model predictions. Though quantifying exact causation is difficult and weather is always multi-causal all signs seem to point in the direction of global warming.  This might surprise some people as global warming may not apply to everyone (the ones with cooler temperatures). On a larger scale though, the global temperatures this year are higher than normal; especially in the Arctic regions near Northern Canada, Alaska and Siberia. This is causing major concerns on topics like melting of permafrost which can cause land to collapse and crumble in on itself.

How is this happening you might ask? Pretty simply actually! Since the oceans are warming up at a certain rate, it affects temperature differentiation between what is considered “cold” regions and what are “warm” regions. This differentiation is why we have weather fronts on a regional level due to this separation of air masses. When a transporting body is slowly warmed though, like the ocean per say. It can greatly affect the larger scale wave patterns that are known as Rossby waves. These waves tend to be greater in size when the temperature differences are less and meander. This combined with a concept called ‘blocking’ where cold or warm air stays in one location for a very long time creates a situation where the colder Arctic air which is usually up in Northern Canada has been transported down to the Midwest in Mid-Atlantic while the warmer air has been shifted to replace the colder air moving South. This has made for temperature on average to be much warmer and drier for the western half of the country and much cooler and wetter for the eastern half of the country.This summer so far has produced weather so below average that the month of July was the coldest month to date in over a 100 years for Lower Midwest. 

Though this is not the only reason that this summer has been so cool; a typhoon that hit Japan in the middle of last month caused temperatures in the Midwest to be much cooler than the normal average.

Weather is not a simple situation, things happen for many different reasons or a combination of them. So it is very hard to put your foot down on one hard answer and say “this caused that”. As an observer though, you have to be deductive yet aware of all possible outcomes. This polar vortex is a perfect example of how climate change could play a role in either giving us a nice break from the summer or a worsening drought and wildfires. This is why everyone needs to start paying attention to climate change, because these issues affect our daily livelihood.

Any questions? I will answer any and all questions if you comment below.