What different warning times could change at Pearl Harbor

What could the United States do with advance warning of the Pearl Harbor attack?

Days of warning could put ships to sea and disperse aircraft; an hour or two would mainly improve crew, boiler, weapon, and aircraft readiness.

With reliable warning of the date, the strongest response is to put the fleet to sea where ships have room to manoeuvre and are not concentrated in harbour. Aircraft can be armed and dispersed, pilots retained at readiness, and ships kept with machinery available. One or two hours is much less useful but still allows crews to be called aboard, steam to be raised, air defences prepared, and perhaps a reconnaissance or strike effort launched. The value of warning therefore depends on whether commanders have enough time to disperse the targets or only to improve their immediate readiness.