We saw last year just how much oil shot up after Ivan. Crude markets remain delicately balanced and if Katrina causes substantial damage to production facilities, oil prices will exceed $70 and could push toward $80 a barrel.

What we've seen over the last couple of weeks with disruptions at copper mines has narrowed the opinion of whether the market is going to be in deficit or surplus. More and more people are thinking it's going to be in deficit this year.

With this week's stock announcement likely to show a fresh decline in gasoline, it adds to market fears caused by the switch to greener fuels.

Copper is often perceived to be the barometer for market conditions and therefore a significant fall in copper prices could remove speculative support from other metals.

It's only political factors that are now holding prices above $60. Iran, Nigeria and Venezuela are potentially affecting supply flow that is driving the rally and is still providing support.

This is really much more important than OPEC supply as their spare capacity is largely heavy and sour and the real shortage is capacity to upgrade such fuels anyway,