At 20:02 16/02/00 +0200, OH2LX wrote:

SID effects are mainly caused by solar EM radiation
and D region effects by hard X-rays. So they travel
with about the same speed than visible light does.

Vaino is right, I mixed up SID (or MDE) with the auroral effects which are
caused by slower particles and occure several days after a major flare.
In the past I observed enhanced propagation on 136kHz in northern
directions at days when aurora was reported on VHF and also recent
observations in Canada showed enhanced propagation several days after a flare.
So maybe (partly) the same mechanisms are involved. Aurora reports on in
DX-clusters could be used as a warning for enhanced LF propagation.

73, Rik  ON7YD