Sizzling Summer Across The Northwest Setting Records


For a part of the country well-known for its grey skies and relatively cool temperatures, the Pacific Northwest’s summer has truly been one few will forget anytime soon, and it’ll certainly be remembered in record books.

The searing heat had Seattle, Washington in the low 90s through the 4th of July weekend, and broadening out, the city has had its warmest start to 2015 in recorded history.

Seattle, world-famous for its grey skies and temperate climate, has basked in 80°+ heat for nearly two weeks, despite an average early July high temperature just in the mid-70s. In fact, down I-5 in Portland, Oregon has had more 90° days so far this summer than Atlanta, Georgia. Portland’s average early July high temperature is in the upper 70s.

The heat, however, hasn’t just been confined to the Pacific coastline. Interior regions like Spokane, Washington saw its warmest June on record, recording an average temperature of 71.4° during the month, a full 1.5° warmer than the previous warmest June (1922). Boise, Idaho is a full 5.2° above average in 2015 so far, with 143 days of above average temperatures compared to just 42 below.

So what’s causing all the heat? The jet stream has been parked over southern British Columbia and Alberta, Canada, for much of June and into early July, allowing warm air to freely flow northward into the Northwest. The desert origin of the airmass has also kept it unusually dry, with just 0.23″ of rainfall in Seattle during the month of June, well below the city’s average of 1.57″ for the month. And unfortunately, the dry air and heat has led to several wildfires in interior Washington, Oregon and through Idaho as well, destroying homes and burning tens of thousands of acres.

In the shorter term, however, there is some much-needed relief on the way. Temperatures are expected to drop closer to seasonal levels along the west coast by the end of the work week and into the weekend. Be sure to stay with WeatherNation for the latest forecast.

Meteorologist Chris Bianchi


How the Jet Stream Influences Heat Waves!


The Pacific Northwest has seen more than its fair share of heat this past month.  Record high temperatures have been the norm in cities such as Seattle and Portland, Oregon, over the past month.  The unusually warm and dry June has also led to many fires such as the Sleepy Hollow fire in Wenatchee, Washington, and the 231 fire outside of Springdale, Washington.


Much has also been said about the jet stream and how its unusual and persistent position in the atmosphere has allowed such extreme conditions to persist in the Pacific Northwest. But what exactly is the jet stream? And how does it cause the unusual heat in the Northwest for much of the past month?

First, the jet stream is a fast flowing, relatively narrow air current found in the atmosphere around 10 kilometers above the surface of the Earth, which forms at the boundaries of adjacent air masses with significant differences in temperature. Sure enough, the jet stream has formed right on the boundary between warm and cooler air.  Some meteorologists also say that the jet stream “allows” warmer air to move northward, while others would state something like the definition above. So which is true?

It turns out that – in some cases – both can be true.  The jet stream is as much the victim of the air masses on either side as well as affecting where it is cooler and warmer.  Certain large-scale phenomena like El Nino affect jet stream patterns, and jet stream itself can effect other large-scale patterns such as redirecting tropical cyclones. 

So is the heat “forcing” the jet stream further north, or is the jet stream “allowing” heat to travel northward? In reality it’s a bit of both. Forecasting the jet stream is like any other long-term forecast problem. Meteorologists are working all the time to develop better models to predict the behavior of the jet stream. Eventually we’ll solve that problem, and in turn be able to predict when and where the next crippling heat wave may strike.


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