Alice Aycock had dinner with the Mondales last Saturday night, her second invitation to the vice president's house. That perhaps best describes where this young New York artist now stands in the American creative firmament.

Her first Washington show, just opened at Protetch-McIntosh Gallery, 2151 P St. NW., continues through Oct. 6. She will also begin construction of a major outdoor piece at the corner of 12th and G Sts. NW in early November, replacing "The Tallest Cowboy Boots in the World."

Since her success at the avantgarde "Documenta" exhibition in Germany in 1977, Aycock has shown solo at the Museum of Modern Art, taught at Princeton and become much in demand worldwide for what she calls her "nonfunctional architecture."

The "Documenta" piece was typical -- a large outdoor construction of raw wood that looked like a playground version of a cutaway medieval castle. Visitors could climb the narrow stairs to the top -- and many were seduced into doing so -- only to find themselves suddenly at a dead end, precariously perched high above the ground.They could either jump or back down.

Such hidden perils and sudden anxiety haunt many of Aycock's works, some built underground. Most, in fact, can be read as three-dimensional metaphors for life in the late 20th century. For by luring the body in one direction, arousing certain expectations and then frustrating or denying them, she has actually produced anxiety and fear in her viewers.

And by bringing both body and mind into play, she has, indeed, added the dimensions of architectural experience to her sculpture. Thus working at the cutting-edge of current art, she is clearly among the most interesting American artists now at work.

The major piece at Protetch-McIntosh, however, (an amalgam of giant wheels, canister pumps and scaffolding entitled "The Central Machine") is different -- and more traditionally sculptural -- in that the viewer cannot physically walk through it. Rather, it must be experienced by looking and reading the accompanying text, which includes the case of a hysterical woman reported by Carl Jung in "Psychology and the Occult."

Taking off from this, Aycock invented her own more detailed case history of a woman who spent hours staring at the sky, convinced that it was going to rain supernatural blue showers."She began to build a machine in which she could sit and scan the sky," writes Aycock. "She thought she could catch the blue rain, draw it off and evaporate it before it fell."

What Aycock has actually built here is the sky-scanning machine, complete with a plastic disc suspended from the ceiling to catch the blue rain. Several mason jars stand at the ready, in case the disc overflows.

The experience is initially literary and intellectual, but also highly sculptural, particularly in the beautifully carved plywood segment suspended above the tableau, a shape inspired by the vertiginous interior of a medieval dome that the artist observed in an old print. From such domes, early scientists observed the heavens. Such fragments from architectural history play a major role in all of Aycock's work.

"This is not pedestal space, but mental, hallucinatory space," says Aycock, who explains her methods further by saying, "When you've exhausted all the normal avenues to achieve what you want, you must make it happen with magic."

If this is not the most magical -- or even the most evocative -- of Aycock's works, it is still worth careful scrutiny, as are the drawings for other projects also on view. Her best works speak without a text, but even so buttressed, this makes the most provocative work currently on view on P Street.

Last year Patricia Forrester made a striking debut at the Fendrick Gallery, 3059 M St. NW, with several huge, multipanel landscape watercolors made on site in her native California forests and woods. Most depicted thickets of trees and dense brush, observed close-up and rendered boldly in what is uaually a very delicate medium.

With those works still in mind, Forrester's new show at Fendrick is something of a disappointment. For while she continues to deal with the same subject matter (this time in upstate New York, where she was an artist-in-residence at Yaddo), and in the same giant format, the visual and emotional intensity seems to have dissipated, giving way to a certain "prettiness" in some works, while others are just plain dull and repetitious.

Outstanding in this show is "White Roses," which takes a refreshingly different tack. Through Oct. 6.

Also on view at Fendrick are some new pen-and-ink seascapes by area artist Robert Singletary, who has not surfaced for some time. But he has obviously used his time well, drawing the Chesapeake Bay in its various modes and moods, under rain, moon and stars. One pencil drawing, a tour de force called "Overcast," took well over 130 hours to complete. It takes but a second for it to cast its spell.

Richard Crozier is yet another California-trained artist who has turned exclusively to landscape painting. His works, however, are highly traditional plein-air paintings in oil, made chiefly in the Blue Ridge Mountains around Charlottesville, Va., where he now teaches art at the University of Virginia.

With short, sure, crisscross strokes and a muted palette, Crozier makes paintings that manage to look fuzzy and impressionistic up close, but almost photographic at a distance. Dividing his canvases horizontally in three, with foreground trees, middleground mountains and background sky, he shows great range, from a tiny, moody portrayal of a few small trees to the exhilarating two-panel "Open Meadow."

Crozier's only problem is that in some works, such as "Long Slope," the sky is laid on with broad, seemingly impatient strokes that do not merge in style, mood or message with the rest of the painting. Through Oct. 3.