I mentioned this article before, now I will go into it in some detail.
Please bear in mind it was written in Feb 2015 especially when it talks about rainfall on the west coast of the US.
Link to the article again:
https://www.scientificamerican.com/article/weird-winter-weather-plot-thickens-as... Quote:Weird Winter Weather Plot Thickens
as Arctic Swiftly Warms Nobody will argue that the weather has been a bit weird. Some cherry pick bits of weirdness to argue the world is cooling: these propagandists never ever quote global temps or science, cherry picking and exaggerating is what they do and most are quite happy to lie to push their view on weather. Almost like they are paid to do so, hmmm.
Quote:Everyone loves to talk about the weather, and this winter Mother Nature has served up a feast to chew on. Few parts of the US have been spared her wrath.
Severe drought and abnormally warm conditions continue in the west, with the first-ever rain-free January in San Francisco; bitter cold hangs tough over the upper Midwest and Northeast; and New England is being buried by a seemingly endless string of snowy nor’easters.
Yes, droughts, cold and snowstorms have happened before, but the persistence of this pattern over North America is starting to raise eyebrows. Is climate change at work here?
This year, as commenters to the ridiculous Dubyne videos have noted the northern Midwest has been HOT. Chicago 70°F from memory. But you can see there in that “bitter cold” the opportunities for snake oil salesmen to crap on about “global cooling.” Easy to do when you don’t cover other parts of the world and their temperatures. Just cherry pick the cold bits.
California suffered nearly five years of drought—notice the reference to a rain free San Francisco above? That broke this year with wild rainfalls, 8" from a storm. I think tho that California will return to a drought when these wild storms stop. Seemed to have been a pattern of California slowly drying out (as is the Colorado River which I will post about soon.)
Quote:One thing we do know is that the polar jet stream—a fast river of wind up where jets fly that circumnavigates the northern hemisphere—has been doing some odd things in recent years.
Rather than circling in a relatively straight path, the jet stream has meandered more in north-south waves. In the west, it’s been bulging northward, arguably since December 2013—a pattern dubbed the “Ridiculously Resilient Ridge” by meteorologists. In the east, we’ve seen its southern-dipping counterpart, which I call the “Terribly Tenacious Trough.”
Quote:These long-lived shifts from the polar jet stream’s typical pattern have been responsible for some wicked weather this winter, with cold Arctic winds blasting everywhere from the Windy City to the Big Apple for weeks at a time.
We know that climate change is increasing the odds of extreme weather such as heatwaves, droughts and unusually heavy precipitation events, but is it making these sticky jet-stream patterns more likely, too? Maybe.
Maybe indeed? Do the wild rain storms “atmospheric rivers” etc over California indicate that the ridge has gone? We know that the ‘windy city’ of Chicago has enjoyed (well some do, some wanted cold and snow) 70°F winter this month.
Considering the weather Europe suffered last month is does seem the trough moved east as has the ridge.
Quote:Slowing, drunken path
The jet stream is a dastardly complex creature, and figuring out what makes it tick has challenged atmospheric scientists since it was discovered about 75 years ago. Even more elusive is figuring out how climate change will affect it.
Jet streams exist because of differences in air temperature. In the case of the polar jet stream, which is responsible for most of the weather we experience around the middle-latitudes of the northern hemisphere, it’s the cold Arctic butting against warmer areas to the south that drives it. (A more in-depth explanation can be found
here.) If jet streams exist because of differences of temperature then it is not hard to figure out that as the Arctic warms the Jet Stream will weaken.
Then and now:
Quote:This is where climate change comes in: the Arctic is warming much faster than elsewhere. That Arctic/mid-latitude temperature difference, consequently, is getting smaller. And the smaller differential in temperatures is causing the west-to-east winds in the jet to weaken.
Strong jets tend to blow straight west to east; weaker jets tend to wander more in a drunken north/south path, increasing the likelihood of wavy patterns like the one we’ve seen almost non-stop since last winter.
The Arctic, just to remind you, is warming faster due to a positive feedback loop: as ice melts in the NH spring and summer sunlight tends to hit dark ocean and be absorbed, warming the ocean. If ice extent was more like what it was in the 1970s say more sunlight would hit light colored ice and be reflected back out to space.
Positive feedback loops are the devil!
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