The Terrace Theater has been given back to chamber music, the Met has abandoned our city, and it will be months before the New York City Opera comes to town, but opera has not left Washington. This week's productions (all one-act operas) are less lavish than what happens at the Kennedy Center, but so are the ticket prices.

Thursday night, Opera DC will open its second production at its new downtown location in Carroll Hall. And last weekend the three-production OperaFest '86 had a promising beginning in the Performing Arts Center of Montgomery College, Rockville. It opened with a Puccini double bill, "Gianni Schicchi" and "Suor Angelica," that was not quite professional but better than one expects of student performances.

OperaFest is a joint venture of the Benjamin T. Rome School of Music at Catholic University, the departments of music and speech, dance and theater of Montgomery College and the music department at the University of Maryland, College Park -- each offering one production. These efforts (including Opera DC's) may lack the glitter or even the routine polish of the bigger opera companies, but their importance in the operatic scene -- particularly in building new audiences and giving experience to young singers -- should not be underestimated. Sunday night's Puccini program showed how badly some young artists need this kind of experience, and it gave solo parts to a few singers who may end up in a chorus somewhere. But it also gave glimpses of a few young artists who may go a long way with a little bit of luck.

Chief among these was Michael Morgan, who conducted with his usual skill and musical sensitivity, carefully controlling his student orchestra and drawing from it a performance that was highly emotive and usually precise if not especially opulent in tone. There were occasional problems of balance between the orchestra and one singer or another, but these were problems of vocal projection, not of orchestral overemphasis.

In "Gianni Schicchi" Sunday night, the musical highlight was "O mio babbino caro" (or rather, since it was sung in English, "O, my beloved daddy"), beautifully sung by Detra Battle, who has the good looks as well as the rich tone essential for the role of Lauretta. As Schicchi, baritone Hyung Roh (a native of Korea) gave a fascinating and highly dynamic performance -- made more interesting if not more convincing by a perceptible non-western accent in his English and his body language. The emphasis in "Schicchi" was, quite properly, more on acting than on singing. A bit of overacting was to be expected of young performers feeling their way into new roles.

"Suor Angelica" was considerably more satisfactory musically -- in part, no doubt, because the cast is all female and good sopranos are easier to find than good tenors. The singing was always adequate and frequently exquisite in some of the sweetest music Puccini ever composed. The frequent ensemble numbers were well disciplined and lovely in tone, and Laurie Nelson gave a very strong performance in the title role.