It's a little like the early 00s when Benfield Hazzard and the Met were touting the May N Atlantic SST profile. Despite what anyone else may say, that correlation has proved to be of limited value. I think SSWs will also come to be seen as a very blunt forecasting tool too.
The SSW occurrences are just a sequence that need to be taken into consideration, they do effect the surface, that is without doubt. Its not the effect that is in question it is the location of effect. The inevitable breakdown of the PV is the missing piece in the jigsaw, when we are capable of predicting its spread etc, it will always be practically impossible to look beyond a few days with any certainty, other than a general trend.
Some researchers, say they suspect that the more frequent polar vortex breakdowns can be tied to climate change.
While climate change is warming the earth, not all parts of the earth are warming at the same rate; the Arctic warming is twice as fast as the world average. That warming has led to historically low levels of sea ice in the region. The melting sea ice, particularly in an area near the Barents and Kara Seas off Siberia, may be linked to the changes in the polar vortex.
There are some excellent papers with ever increasing correlation of evidence to support these views. There apparently is also some evidence that winters will become more sever but shorter due to this.
So when the LR forcast have a good strong SSW and split PV to play with, it is inevitable that somewhere in the NH there will be some extremes of weather, made easier by the known fact that an SSW is likely to effect our neck of the woods enough to predict a probability that it will be colder than normal with the chance of it being very cold.
Edited by user
21 January 2019 11:01:37
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