Sunday, November 2, 2014

Wacky Jet Stream Partly to Blame for Carolina, Maine Snows And Other Recent Weather Weirdness.

The scene in Bangor, Maine this morning. And
this is before the worst of the storm arrived.  
Every so often, the weather really goes off the rails, and this weekend is one of those times.

You might have seen all the news about the snow in the Carolinas yesterday.  It was the earliest in the season they'd seen such snowy weather.

Today, Maine is getting an epic snowstorm, with up to a foot of snow and gusts to 55 mph expected. This is something that normally doesn't hit until December. And even by December standards this storm is really something up there.

The cause of all this big weather in the northern hemisphere is, of course, the jet stream. We can always blame the jet stream for big weather.

It usually has a wavy, curvy path, trending northward in one part of the world, then turning a corner and sliding southward, only to head north again downstream.

You start getting into problems with the jet streams curves, those northward and southward excursions, when they get really intense, going way, way north, then way, way south and so on.

This is called an "amplified" pattern.  Think of it this way: When sound is amplified, it's loud. When the jet stream pattern is amplified, that means the weather is loud.

So you get we had in the United States and elsewhere in the world this week. The amplified jet stream was able to grab a strong weather disturbance from way up near the Arctic, and slam it down way south into the Carolinas.
Amazingly, this is not Buffalo, New York in January
but Gilbert, South Carolina yesterday, November 1.
Photo by Tom Dominick of The State newspaper.  

That's why it snowed there. Had the jet stream not been so extreme, not so amplified, and more normal, there would probably have been a run of the mill cool spell near the Great Lakes and into the Northeast.

And if anything happened in the Carolinas, it would have been a normal autumn rainfall.

That amplified jet stream then curves way, way north off the East Coast, and that is, in part, why there's such a strong storm hitting Maine today.

Elsewhere in the northern hemisphere, the jet stream is also pretty amplified. It's contributing to a strange week of weather in Europe, including record late season warmth from Finland to Britain,
a very odd, extreme early season ice storm in Bulgaria, and a reported damaging tornado today in Leicestershire, England. 

There's no rest for the weary, either. It looks like some fairly strong storm systems will keep crossing the nation over the next two weeks. Long range forecasts are notoriously dicey, so I can't really give you details on how those storms over the next couple of weeks will play out.

We also have the inevitable question about this amplified jet stream I've been talking about: Does it have anything to do with global warming?

The answer is: Maybe.

The theory is that since the Arctic is warming faster than places near the Equator, the temperature difference between the tropics and the Arctic isn't as great as it once was. A well-behaved jet stream depends on this contrast of temperatures between the North and the South.

If the contrast isn't as great as it once was, that means the jet stream has more room to get "wavy" or amplified, so as the planet warms, we get more extreme weather.

Scientists still disagree on whether this aspect of climate change is real.  The consensus, by my reading, seems to be that global warming is influencing the jet stream, but so are other things. The bottom line is this particular aspect of the science is not well understood. It needs more work.

There's studies going on to determine if this potential effect of climate change, the wacky jet stream, is actually happening, or just a false lead or illusion.

Stay tuned on that one. Meanwhile, enjoy the big storms. Or at least try to.

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