I was discussing this at work earlier this week with a Chief forecaster. It
has been pretty persistent for a few weeks now, never moving. It's almost as
if the progressive Rossby pattern (still spot on Len!) has cut off that part
of the Arctic leaving it to cool and cool .. Seas just to the east of
Greenland are now cold and this reservoir of deep cold air is like a tap
opening up and flooding south to re-inforce the Atlantic baroclinicity in
the cold westerly, preventing blocking further east. Over time the colder
air has come further south and now Scotland is set to turn very cold, though
still with milder interludes in the mobility. The big question is will a
mid-Atlantic ridge amplify due to upstream trough extension over Canada. All
eyes to the Pacific I guess. So it seems for the time being at least we are
looking at cold mobility with lots of fascinating wintry detail to get hold
of, especially, but not exclusively in northern areas!

Ciao, winter weather watchers :-)

Will
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