“IF WE EXPECT LARGE CHANGES but are very uncertain as to what precise form these changes will take, then our confidence will be weak.” So wrote John Maynard Keynes in his classic General Theory of Employment Interest and Money in 1936. That might explain why consumer confidence fell 14 percent after Katrina cut a swathe through Louisiana, Alabama, and Mississippi, to its lowest level since 1992.

Like markets, consumers abhor uncertainty. And uncertainty abounds. Weather forecasters are now joined by economic forecasters as the stars of 24-hour business new channels. As the economists dance to the weather forecasters’ tune, and revise and re-revise their own forecasts, oil and natural gas prices dance to the economists’ tune.