Tuesday, December 21, 2010

Snow, Rain and Climate Change

The Guardian has an interesting article titled “That snow outside is what global warming looks like.” Good reading. It has to do with the lack of polar ice changing arctic atmospheric circulation, causing a couple of places in the north to become colder and much of the northern hemisphere to become a lot warmer. Turns out scientists predicted precisely this, and we weren’t paying attention. What else is new?

I’ll tell you what else is new; six days of rain in San Diego.

We are in not one but two Pacific phases which should keep the Jet Stream north of San Diego and mean dryer weather here, The Pacific Decadal Oscillation, and La Nina. Both of these are in the cold phase, and either one alone would tend to mean a dry winter for us. So what do we get?

The Jet Stream currently stretches from Hawaii almost straight East to about Los Angeles, and has been parked there for almost a week, bringing record rainfall to the southern part of the state. San Diego is on the very southern edge and is getting pretty light rainfall; totals are much heavier just to the north of us.

Not only is this the case now, but we have had half a dozen rainstorms move through before this came to pass, sooner and more frequently that would normally be the case at this time of year. None of them have been particularly large or wet, but they have come farther south earlier in the season than is usual and, given the Pacific phases, one would expect the opposite to be the case.

I’m not in a position to know what any of this means, but it’s interesting.

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