"Eskimo Will" wrote in message
...

John Austin ex MetO told me in 1976 that long range forecasting would
improve if we could understand the stratosphere better? I still think he
was right! But we still have a lot to learn.

Will

There is an interesting article in Wikipedia about SSWs.

IMHO, the last point is especially so:

"There exists a link between sudden stratospheric warmings and the
quasi-biennial oscillation: If the QBO is in its easterly (westward) phase,
the atmospheric waveguide is modified in such a way that upward-propagating
Rossby waves are focused on the polar vortex, intensifying their interaction
with the mean flow. Thus, there exists a statistically significant imbalance
between the frequency of sudden stratospheric warmings if these events are
grouped according to the QBO phase (easterly or westerly)."

Cheers, Alastair.