With just six days to go before Federal Reserve policymakers sit down in Washington, exactly what decision they'll make on interest rates now and in coming months has become pretty much anyone's guess, and investors and Wall Street economists are doing just that.

Over the past year, Fed leadership has gone out of its way to signal its intentions on interest rate hikes aimed at quashing hot inflation, relying on a steady stream of economic data inputs to guide its actions.

But now Fed Chair Jerome Powell and his colleagues find themselves needing to respond in real time to turmoil in the banking system after the collapse of two large regional U.S. banks and Swiss regulators having to pledge assistance to Credit Suisse, developments that are reshaping domestic and international financial conditions on a daily or even hourly basis.