Here are the latest index values from NOAA's Climate Prediction Center:
And here are some of this morning's British headlines"
Big freeze to hit Britain as temperatures plummet to -10C
UK weather: Temperatures set to plummet to -10C this week as parts of Britain wake up to snow - pics
You don't know where the Arctic 'fence' will open and the timing is always iffy.
If the gates were to open over the U.S. Northwest all that -50F air over Fairbanks would come spilling into the contiguous Lower 48.
Here's the quick tutorial from the Jan. 9 post:
Technically, the Arctic Oscillation is a measure of atmospheric pressure variations at sea level north of 20N latitude. Where an Arctic high develops affects weather thousands of miles away....
Here are the ensemble model runs at NOAA's Climate Prediction Center.
For a major change the index has to go below and stay below the zero line for at least a few weeks