Fed Chair Powell Says Policymaker Projections Are Subject To Uncertainty, Not A Plan, Or Decision; No Preset Course, Meetings On Meeting By Meeting Basis; Rates Now In A Plausible Range Of Neutral; Committee Judges Reserve Balances Have Declined To Ample Levels; Purchases Are For Sole Purpose Of Reserve Management; Reserve Management Purchases May Remain Elevated For A Few Months To Alleviate Money Market Pressures; Thereafter Expect Purchases To Decline