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?
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| 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.
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| 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.
