IMAGINE A HUNT in which the Master of Fox Hounds is replaced just as the pack picks up the scent. Add a dense fog. That’s a good description of the circumstances in which the Federal Reserve Board’s monetary policy gurus find themselves as they hunt for the interest rate that will allow the U.S. economy to grow at a sustainable, non-inflationary rate at a time when Alan Greenspan is about to be replaced by Ben Bernanke.

The Fed knows a few things with a reasonable degree of certainty. The storm-tossed economy continues to grow at a rapid rate. The latest preliminary figures–because of Katrina, emphasis must be on “preliminary”–show that third-quarter GDP grew at an annual rate of 3.8 percent, and suggest that it would have grown at a sizzling 5 percent had it not been for a temporary reduction in private inventories and the impact of Katrina. The economy has now grown at a rate of more than 3 percent for 10 consecutive quarters.