When will a court overturn a conviction for unlawful possession of a controlled substance based primarily on circumstantial evidence?

"The same standard applies when the conviction rests primarily on circumstantial evidence. [Citation.] Although it is the jury's duty to acquit a defendant if it finds the circumstantial evidence susceptible of two reasonable interpretations, one of which suggests guilt and the other innocence, it is the jury, not the appellate court that must be convinced of the defendant's guilt beyond a reasonable doubt. [Citation.] '"If the circumstances reasonably justify the trier of fact's findings, the opinion of the reviewing court that the circumstances might also reasonably be reconciled with a contrary finding does not warrant a reversal of the judgment. [Citation.]"'" (People v. Kraft (2000) 23 Cal.4th 978, 1053-1054.)

The applicable law is clear. "'Unlawful possession of a controlled substance for sale requires proof the defendant possessed the contraband with the intent of selling it and with knowledge of both its presence and illegal character. [Citation.]' [Citations.] Intent to sell may be established by circumstantial evidence. [Citation.]" (People v. Harris (2000) 83 Cal.App.4th 371, 374.) Appellant concedes he was knowingly carrying an illegal substance in the form of cocaine base, but he argues the circumstances of his possession do not reasonably suggest he intended to sell the drug.