"Waghorn" I will look up the original reference and post further if it's
illuminating.
There is a note about a possible relation to the Madden Julien Oscillation
as well,

The reference is-
Plaut&Vautard,Spells of Low Frequency Oscillations and Weather Regimes in
the Northern Hemisphere,J Atmospheric Sciences,V53,no2,1994,p210-
(not available online unless you purchase from the AMS website)
They use Singular Spectrum Analysis of 700Hpa GPH fields .Can't comment on
the technique ,.but the paper seems well regarded and cited.
Apparently interaction with topography may play a role but is not a
sufficient explanation,synoptic eddy forcing is the major player.Particular
phasing of the 30-35 day oscillation is found to precede major
European-Atlantic blocking,as occurs in the striking pattern pointed out by
Philip.This has interesting results for predictability of such blocks.
Whether extratropical oscillations precede or lag tropical oscillations was
questioned in the nineties.I believe the view now is that at least some
precede-the mechanism is the movement of PV anomalies with the Rossby waves
equatorward triggering tropical convection.There are of course feedbacks,and
tropical heating anomalies are known to effect the downstream long wave
pattern.
Anyway,as you point out ,there are a multitude of weak teleconnection
patterns,

--
regards,
David

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