Too often, when excellent Washington-based jazz artists decide to reside inside the Beltway, they're relegated to being "one of jazz's best-kept secrets." Vocalist Sunny Sumter is one such artist. Her voice is a delightful sunburst of melodic invention. And judging from her two previous albums, and most recently her Wednesday night performance at a packed Blues Alley, time is overdue for someone to snitch on this particular "best-kept secret."

Complemented by a rhythmically astute trio led by noted pianist John Hicks, Sumter radiated onstage. Her effervescent demeanor was at once commanding and casual. Mid-tempo songs underpinned by infectious rhythmic grooves seemed to be Sumter's forte. She opened with the swinging "Where's the Love," which ingeniously navigated between reggae and lithe samba, and nearly tore the roof off with an enchanting rendition of Abbey Lincoln's "Talking to the Sun." On both tunes, Sumter enlivened the lyrics with glowing optimism and candor.

From one listening, it's obvious that Sumter has a powerful voice. That was best illustrated when she opened "Rememberin'," an earnest tribute to some of jazz's great leaders, unmiked against James King's sturdy bass lines. Luckily, she's perceptive enough to use restraint to keep from overpowering the lyrics and melodies. She also kept scatting -- a technique in which many young singers seem obliged to indulge -- at a refreshing minimum.

Although Sumter's most persuasive with upbeat, mid-tempo songs, she's sounding increasingly comfortable with slow-burning ballads. Her readings of Stevie Wonder's "Overjoyed" and the standard "My One and Only Love" sounded a bit stilted in places, but her sumptuous rendition of Billie Holiday's "Detour Ahead" was one of the evening's highlights. Sumter's luminous voice, in direct contrast to Holiday's alluring sadness, shed new light on her burgeoning talents.