yes they are predictable..
they are caused by magnetic activitiy
which is often a direct result of
sun spot activity or solar storms.
If there is a burts of energy spouting off of the sun
the "coronal mass Ejection" will trigger a
light display.

I am on anb e-mail list for the aurora watch,
where i will be notified if a CME happens
and they will be able to predict which
latitude will be most likely to view
the lights..there is a great gallery
online...
http://www.spaceweather.com/aurora/gallery_06nov01.html
http://www.spaceweather.com/aurora/gallery_06nov01.html
http://www.sel.noaa.gov/pmap/

they are more visibe. more frequent,
more colorful and more strong
every 11 years when we have a cycle of
solar flares and geomagnetic storms.
"sun spots"

this was jsut last year, so wait for
10 years for another such show.

these magnetic storms sometimes
cause interference with radio
and satellite signals, cell phones
and other electronic devices.