Winter '18 / '19 - Sudden Stratospheric Warming: Watch #1

Polar vortex (PV) displacement event appears to be in the cards come Christmas.

Full flow reversal + warming ==> major sudden stratosphere warming (SSW) event ...

BLUE:  into the board ==> east wind (-U)
ORANGE:  out of the board ==> west wind (U)

"A major SSW occurs when the 10 mb 60°N zonal mean zonal wind reverses from westerly to easterly and the 10 mb zonal mean temperature gradient increases poleward of 60°N." (.pdf)

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Last winter's SSW event crash-landed over the UK (weeks of late season snow + cold)

This year ... round and round she goes.
Where she stops ...
Nobody knows.