It seems that the bits of rock and debris that produce this meteor storm have separated from the comet nucleus and stream behind and ahead of the main body of the comet. For this reason, in those years, such as this year, when the Earth is predicted to pass close to the comet, it's more likely that a meteor storm may occur. It's very unlikely that we'll see this kind of fireworks this year, because in 1933, as was the case in 1946, the Earth crossed the comet's orbit after the comet itself passed by. This year, the Earth will pass through the orbit seven weeks before Giacobini Zinner arrives. Ostensibly, there's more cometal debris in the orbit once the comet passes by.
All bets are off, but it's certainly worth taking a look.
However, if we strike out in the next two nights, all is not lost. In the year 2005, the Earth will pass behind Giacobini Zinner, and thus we should be in a better position than this year to witness a meteor storm. We'll talk about this more in a few weeks.