So I know I have at least one reader, Mike, from Pennsylvania. How’s the weather out there?! Cold yet?
There are records being set all over the US and Canada, but not just cold. It was -45F (-40C) in Maine yesterday a new state record. While in California, the huge High pressure that is giving us all the fog brought 73F (21C) temperatures to San Jose, a new record. And strangest of all, the Pineapple Express that normally washes over us this time of year is being deflected into Alaska, where a new record of 53F (12C) was set… this only a week after a low of -50F in the same town (a change of 100 degrees Farenheit!).
All this data is courtesy of Jeff Masters:
So WHY is it so cold??
a sharp kink in the jet stream is responsible for the wild weather we’re having. A ridge of high pressure over Alaska is forcing the jet to bow northwards into northern Alaska, allowing warm air from the Hawaii area to stream northwards over the region. Whenever the jet contorts into such a pattern, there must be a return flow of cold air from the pole that develops. That is occurring over the eastern half of the U.S., bringing us our Arctic air blast.
He also had some very interesting things to say about his “top climate story in 2008“.. the loss of Arctic Sea ice and how it might be directly affecting our weather in North America.
The impact on the jet stream
The unprecedented melting of arctic sea ice the past two summers has undoubtedly had a significant impact on the early winter weather over the Northern Hemisphere. Several modeling studies presented at the December AGU meeting showed that sea ice melt on this scale is capable of injecting enough heat into the atmosphere to result in a major shift in the jet stream. Dr. Overland remarked that the early cold winter over North America this winter, and the exceptionally cold and snowy early winter in China last winter, were likely related to arctic sea ice loss. The sea ice loss induced a strong poleward flow of warm air over eastern Siberia, and a return flow of cold air from the Pole developed to compensate. Thus regions on either side of eastern Siberia–China and North America–have gotten unusually cold and snowy winters as a result.