I had heard it suggested by a knowledgable source that a White House representative was listening in when National Hurricane Center Chief Max Mayfield gave that briefing to Brown and Chertoff before Katrina hit.
But according to this August 30th article in the St. Petersburg Times, on Sunday the 28th, Mayfield arranged a video conference call with President Bush himself at the Crawford Ranch during which he explained the hurricane's force and destructive potential.
Perhaps this is common knowledge. But I hadn't heard it before. And it would seem to leave little question that the president himself knew the critical information from Mayfield before Katrina even made landfall.
Said Mayfield, according to the Times: "I just wanted to be able to go to sleep that night knowing that I did all I could do."
(ed.note: Special thanks to TPM Reader BP for the tip.)