California Drought: The Jetstream Connection
July 16, 2014
Back now from a run up the California Coast, where the drought is very much in evidence.
Concurrently, in tandem with warm and dry conditions in the west, we’ve seen a huge bubble of colder air sweep across the East. Remind you of anything?
It will be unseasonably chilly in the eastern part of the United States this week, due to a peculiar weather pattern that’s causing deep waves in the jet stream. One of those big waves is bringing cool air down from the northeast Pacific and the Arctic. This will cause nighttime temperatures to be, on average, in the 50s or 60s on Tuesday and Wednesday.
So is it the polar vortex, or isn’t it? That’s been the big debate among meteorologists and news outlets. But according to at least one scientist, that debate misses a more important point about the unusual weather pattern sweeping the United States — that it’s causing extreme weather in other parts of the country.
“We’ve got this cool air coming down over the eastern half of the country, and that’s gonna just be kind of nice,” said Jennifer Francis, an atmospheric scientist and research professor at Rutgers University’s Institute of Marine and Coastal Sciences. “But along the east coast, we’re looking at storms and floods. On the west coast, we’re looking at heat and fires. And it’s all part of this jet stream pattern.”
A particularly wavy jet stream is what is causing the so-called “polar vortex,” or cold air from the Arctic, to travel down to the United States, Francis said. The dramatic and unusual southward swoop, shown in the map on the right, allows air from the cold north to travel south. The same thing happened this past January, when a dramatic southward swing of the jet stream brought increased cold air to an already-freezing region. That was big news, extreme weather-wise.
Now, the “polar vortex” is making for fairly mild weather. But at the same time, that same wavy jet stream is swinging northward in the western United States, bringing increased heat to an already-dry and wildfire-stricken region. Extreme weather-wise, Francis says, this is a bigger deal.
The pattern is very reminiscent of the “ridiculously resilient ridge” that brought last winter’s brutal polar vortex to the east, while keeping the west coast dry. You may have seen my video on this, but still worth skipping to the last third for review and comparison with what we are seeing now.