This CNN report has a lot of filler, but it does link to a segment on a "whistleblower". But, it also ends up being CNN reporting on someone who apparently used CNN as a source for remarks by Blanco, which are then re-reported by CNN:
"We told these fellows that there was a killer hurricane heading right toward New Orleans," Leo Bosner, a 26-year FEMA employee and union leader told CNN. "We had done our job, but they didn't do theirs."
Bosner's storm warning came early Saturday, three days before Hurricane Katrina came ashore in eastern Louisiana.
"New Orleans is of particular concern because much of that city lies below sea level," he warned in his daily alert to Homeland Security secretary Michael Chertoff, then-FEMA chief Michael Brown and other Bush administration officials.
"If the hurricane winds blow from a certain direction, there are dire predictions of what may happen in the city," it said.
Those quotes appear to have originated with Gov. Kathleen Blanco, and not Bosner. I don't know if this National Situation Update: Saturday, August 27, 2005 is what that's refering to, but it attributes those last two quotes to Blanco, and it cites "Various media sources" as its sources.
Those quotes appear to have first appeared in CNN's Aug. 26 article "Forecasters: Katrina to aim for Mississippi, Louisiana":
In anticipation of a possible landfall, Mississippi Gov. Haley Barbour and Louisiana Gov. Kathleen Blanco declared states of emergency Friday.
Blanco said "very well-coordinated evacuations" were planned that will be enacted "if there's a direct threat."
New Orleans is of particular concern because much of that city lies below sea level.
"It's always a huge concern, because there's a very large lake, Lake Pontchartrain, that sits next to New Orleans, and if the hurricane winds blow from a certain direction there are dire predictions of what may happen in that city," Blanco said.
What an odd loop! There's a possibility she was quoting Bosner, or CNN got its attributions wrong. Let's ask them and find out.
And, from Sep 11's "FEMA Weathers Storm From Critics":
So what happened as Katrina approached? On the Saturday morning two days before the hurricane struck, FEMA's watch commanders issued a warning.
"We put a situation report out at 5:30 a.m. saying a catastrophic hurricane is headed straight, dead-center for New Orleans and Brown and Chertoff and these people did nothing," Leo Bosner says.