Hi. I found the following links which may help you.
§ 49. blatant / flagrant. 3. Word Choice. The American Heritage Book of English Usage. 1996
blatant, flagrant, fragrant Often misused or confused. Use blatant to describe something that's both very noticeable and offensive, especially if it's loud and noisy. It has a negative meaning and does not simply mean "obvious." Use flagrant to describe something even worse; it's shocking and breaks laws and trust. Also, blatantly obvious is redundant. Use either blatant or obvious, depending on the point you're making. And be careful not to confuse or mistype flagrant and fragrant. Use fragrant to describe something that smells nice. (from Garbl's Editorial Style Manual: B)
Blatant(ly) or Flagrant(ly)?
blatant: Definition, Synonyms and Much More from Answers.com
flagrant implies shocking and reprehensible, while blatant is obvious, contrived, and usually obnoxious; flagrant is a stronger term than blatant (from thesaurus.com)
Hope this helps!