Speaking of harmonic convergence -- and if we weren't we are now -- the Washington dance scene is coming up with a corker this week. The crux will be a mighty tetrad spearheaded by a Kennedy Center showcase for Washington dance, followed by the New York City Ballet, the Washington Ballet and Yoshiko Chuma and the School of Hard Knocks.

This town has had periods of densely packed dance activity before, more and more of them in recent seasons. Even so, the present case is unusual. It's hard to remember a seven-day interval in the past in which such widely divergent styles and genres of dance were so richly represented.

If, from the dance consumer point of view, this makes for some agonizing decisions about what to see and what to forgo, it is on the whole far preferable to facing no decisions whatever. Obviously if too many good things are happening at once, no one person can take it all in and something must be sacrificed. But that's exactly what cosmopolitan culture is about, and for better or worse, that's where dance in Washington has been headed ineluctably over the past decade and a half.

Monday night -- usually the quietest night of the week for all forms of theater -- brings the first of four major entries in this terpsichorean bonanza (and that's if one discounts the not inconsiderable events of today and tonight, including performances by the Houston Ballet and Kei Takei's Moving Earth as well as a New Choreographers Showcase at Dance Arts Moving Arts). It's "A Celebration of Dance," a highly important "first" for the Kennedy Center in which no fewer than six Washington-based dance groups will be afforded the invaluable exposure of a Terrace Theater performance. The participants will display creative wares ranging in idiom from traditional and experimental modern dance to pluralistic strains of international ethnic dance.

Thursday night is perhaps the week's epitome, with the three other principal components of this artistic bounty appearing simultaneously at different sites, each exemplifying a separate and autonomously significant slice of the Washington dance spectrum, to wit:

The incomparable New York City Ballet, which will have begun a two-week engagement at the Kennedy Center Opera House Wednesday night, marking a return to Washington after a gap of two years, will be presenting the Washington premiere of Peter Martins' "Ecstatic Orange," along with George Balanchine's "Scotch Symphony" and Jerome Robbins' "In G Major." This is the contemporary ballet troupe par excellence, and its frequent Washington visitations have been an indispensable factor in keeping us honest -- that is, in holding a yardstick of balletic perfection vividly before our eyes and minds.

The Washington Ballet, our globe-trotting indigenous classical troupe, which has hewed to a high standard of its own within the realm of chamber-sized (21 dancers) ballet, will present the first of four performances at Lisner Auditorium of one of its strongest and most attractive programs ever. It features company premieres of works by Balanchine, Paul Taylor and the company's associate artistic director Choo-San Goh.

Finally, Thursday night will also introduce to Washington for the first time Yoshiko Chuma's "Bessie"-award winning New York troupe, the School of Hard Knocks, which will give four performances in the ongoing, month-long "Japan-America Dance Project" series organized and hosted by Washington's preeminent contemporary dance center, the Dance Place. ("Bessie" is the nickname for the Dance Theater Workshop's annual New York Dance and Performance Awards.) Chuma arrived in the United States from Japan in 1977, founded her troupe five years ago and has been making heavy waves in the forefront of new dance ever since.

The Kennedy Center's "A Celebration of Dance" is part of a new series, "Washington, Front and Center!," aimed at bringing Washington artists into the spotlight of the national cultural center, and generously supported by the Meyer Foundation and the April Trust. The inaugural dance program has been curated by the outstanding Washington choreographer Liz Lerman, whose goal was to display a rainbow spectrum of area activity that would include established troupes as well as specially promising new ones. Shizumi Dance Theatre, for example, which will lead off the evening, has been locally based only for the past two years and though it has toured widely elsewhere, the "Celebration" will mark its first Washington appearance. Artistic director Shizumi Manale fuses elements from her traditional Japanese artistic background with western dance and music influences.

Newer still is the two-woman duo Zeniyaz, cofounded last year by Brazilian native Zenaide Silva and California-born Lori (Nia) Love, whose exploratory choreography draws from sources ranging from Africa and Latin America to the Orient. The more familiar area groups appearing include Larry Warren and Dancers, in the premiere of Warren's "For Lorca"; the D.C. Youth Ensemble, led by director-choreographer Carol Foster; dancer-choreographer Deborah Riley with Perlo/Bloom & Company; and Sharon Wyrrick and Full Circle.

In an effort to make the evening feel as inclusive as possible, Lerman has also enlisted a number of key Washingtonians to serve as onstage hosts for the program, including the Kennedy Center's artistic director Marta Istomin, as well as dance spokespersons Mike Malone, Murray Spalding, Sherrill Berryman-Miller, Anne McDonald and Maida Withers.

The New York City Ballet's Thursday night program is the tip of a colossal danceberg that will comprise 17 ballets in all, among them the Washington premieres of Martins' "Les Petits Riens" and "Les Gentilhommes" (as well as "Ecstatic Orange"); the Washington premiere of the Jerome Robbins-Tywla Tharp collaboration "Brahms/Handel"; new productions of Balanchine's "Swan Lake" and "La Sonnambula" as well as seven other works by him; and four additional ballets by Robbins.

The Choo-San Goh work the Washington Ballet will perform at Lisner is one he created originally for Israel's Bat-Dor Dance Company in 1985. Entitled "Moments Remembered," it is set to Scriabin's Third Piano Sonata. The new Balanchine entering the company's repertory will be "Square Dance," the 1957 opus that blends rustic Americana with typical Balanchinian neoclassic formalisms, all to Baroque music by Corelli and Vivaldi. The program will also see the company premiere of Taylor's "Esplanade," the first genuine masterpiece of modern dance choreography the Washington Ballet has acquired.

"The Big Picture" is the evening-length work choreographer Yoshiko Chuma and the School of Hard Knocks will present at Dance Place. Typically for Chuma, it's a four-way collaboration between herself, rock composer Nona Hendryx, graphic artist Yvonne Jacquette and scenarist Catherine Bush, who have striven to devise interactive imagery centering on the idea of flight and its role in modern society. An excerpt from this work was one of the highlights of the recent 1987 "Bessie" presentations at New York's City Center.

What else can be said about a week's dance lineup as provocative as this, except, maybe -- "POW!"