Is there any way to anticipate exceptional Aurora Borealis viewing conditions? I've always wanted to see the Aurora Borealis, but never had the opportunity, since it is so rarely visible in my area (Pennsylvania).
However, last week was apparently a rare opportunity of exceptional visibility.  
Unfortunately, I missed my opportunity, as I did not find out about it until the next day.
Are there any good resources or strategies for anticipating opportunities like this?  Are coronal mass ejections like the one that precipitated this event predictable?  If so, are such predictions available to the amateur public?
 A: I use Twitter user Aurora_Alerts and its corresponding RSS feed to make aurora alerts show up in my RSS reader (which happens to be Opera). 
Aurora_Alerts posts messages like In 53 minutes the Aurora should be Quiet 2.33 Kp and 31 minutes the Aurora should be at 'STORM' LEVEL! It's On!! 7.33 Kp (Kp is related to the K-index which quantifies disturbances in the horizontal component of earth's magnetic field with an integer in the range 0-9 with 1 being calm and 5 or more indicating a geomagnetic storm.).
SpaceWeather is a source for following the general state of the Sun and alerts of coronal mass ejections (CMEs), but it may not be updated frequently enough to get alerts in time (and it is quite tedious to keep checking it). 
A: Geophysical Institute from Alaska predictions worked for me quite well.
A: The Kp monitoring sites already suggested (and many others) are useful, but don't guarantee particular conditions for particular readings - the most spectacular display I've ever seen was ~Kp5, but I've been out in higher Kp readings and seen virtually nothing.
Personally, I follow several other people on Twitter who are into aurora spotting and live within a hundred miles of me - that's a much better guide to whether a display is visible or not.  
Taking this to an extreme, it's possible to automatically monitor Twitter's live stream with their API, and detect peaks in worldwide "chatter" about aurora.  My personal version of this is at http://webdesignhighlands.co.uk/twaurora , and there's a more mature version of the idea at http://www.aurorasaurus.org/
