Katherine Porter, a painter who carried an intuitive, dreamy, vividly colored branch of Expressionism into the 21st century, died on April 22 at her home in Santa Fe, N.M. She was 82.

LewAllen Galleries in Santa Fe, which represents her, said the cause was a heart attack.

Ms. Porter used a standard, if slightly idiosyncratic, vocabulary of early modernist abstraction: thick, freely floating steps, curves and spirals; triangles, squares and a plethora of circles; occasional incursions into meaning and representation, like snippets of writing, depictions of barbed wire or shapes that evoke buildings, weather or pointed arch windows; and stormy collisions of these elements that seemed to have overflowed onto the canvas under their own power.

What was distinctive about Ms. Porter’s version was its large scale, its unmistakably unfiltered quality — and its color.

Unlike the figurative Expressionists, who altered colors to heighten their emotional effects, or the purely Abstract Expressionists, for whom colors had meaning only on canvas, Ms. Porter had a palette that was entirely personal, making contact with the natural world just long enough to spirit viewers back into her own psychology.

In “Fire, Water, Sun and Moon,” a 1979 canvas more than 11 feet long that belongs to the Museum of Fine Arts Boston, a diagonal wave of curling blue lines shoots across the frame while a small yellow sun in the upper right corner shines in vain against a troubled pink sky. Pink sky and blue waves spark a sense of recognition — but toppling gold and lavender towers above the wave, and a thrumming black circle beneath, transform the scene from an external place to an interior vision.

“New York Number,” at the Metropolitan Museum of Art, is divided into red, white, orange and black quarters that support a vibrant, mosaic-like rectangular procession of little dashes in roughly the colors of the larger sections, with the addition of light blue. It doesn’t quite harmonize, but it isn’t distinctly dissonant either. Instead, the piece conveys a lingering emotional turmoil.

A recent retrospective at LewAllen Galleries, filled with smoky oranges, cloudy blues and unexpected grays, was titled “Brilliance of Spontaneity Untamed.” The gallery credited those words to a remark made by the Picasso scholar Lydia Csato Gasman.

Of course, spontaneity isn’t for everyone. Ms. Porter’s work drew mixed notices from critics.

Writing in The New York Times in 1983, John Russell described her as “a one-woman fireworks display.” But “like most fireworks displays,” he added, “she has a limited formal repertory.” Thomas Lawson, writing in Artforum in 1981, blamed her for “conveniently forgetting to include the hard kernel of radical thought” that had originally motivated the Expressionist techniques she adopted.

What was beyond doubt was Ms. Porter’s devotion to her approach. After describing her, in New York magazine in 1987, as “someone who has never tempered a brushstroke or bothered to suppress a wayward impulse,” Kay Larson went on to suggest that Ms. Porter had, “by sheer endurance and grit, turned her art’s weaknesses into a kind of signature.”

Katherine Louanne Pavlis was born on Sept. 11, 1941, in Cedar Rapids, Iowa, to John Pavlis, who was vice president of his father’s office furniture factory, and Evelyn (Fawcett) Pavlis, who by 1944 was raising three small children.

Mr. Pavlis was killed while serving in the Navy in World War II. Ms. Porter’s mother later married Jack Greedy.

Ms. Porter herself married twice, first to Stephen Porter, a sculptor and a nephew of the painter Fairfield Porter, and then to Mark Dietrich, a carpenter. They separated, and he died a few years later. She is survived by a brother, Ned Greedy, and a sister, Karen Pavlis Sielaff.

In 1963, Ms. Pavlis graduated from Colorado College, where she studied art with the painter Bernard Arnest, first heard about Abstract Expressionism and Pop Art, and, as she recalled in a recent video interview, learned to be “free” in her work.

At Boston University, where she spent her junior year, her experience was the opposite: She followed rigorous courses on anatomy and perspective with Walter Murch and Conger Metcalf.

“We painted eggs for a semester in Conger Metcalf’s class — drew them and then painted them,” she recalled.

While her first husband pursued an M.F.A. at Cornell University, Ms. Porter worked the night shift at a bowling alley and sewed Naugahyde at a furniture factory. She eventually found a job teaching grade school.

After moving alone to Boston in 1967, she continued teaching, working at the Storefront Learning Center in the South End neighborhood and at a Quaker school in Cambridge. She also befriended the art dealers Joan Sonnabend and Phyllis Rosen, who helped her get a National Endowment for the Arts grant in 1972. They also connected her with the New York gallerist David McKee, who began showing her work in 1974.

By then she had already sold her first painting — to the dealer and painter Betty Parsons, whom she met through another painter, Aline Porter, her mother-in-law.

Ms. Porter was awarded honorary doctorates by Colby College and Bowdoin College, and her paintings appeared in the Whitney Biennial in 1973 and 1981. In New York, in addition to Mr. McKee, Sydney Janis and Andre Emmerich showed her work. It has been collected by the Whitney Museum, the Guggenheim, the Museum of Modern Art and the Metropolitan Museum of Art.

After moving to Boston, Ms. Porter lived a peripatetic life. In 1976 she moved to Belfast, Maine, where she converted a former hardware store into a studio and lived above it. She also spent nearly a decade in Montreal, with summers in Nova Scotia; visited the Galápagos Islands with her first husband and Buenos Aires with her second; made annual trips to Provence; returned to Maine; used a rented loft in New York as a home base for visiting-artist work nearby; and, just last year, relocated to Santa Fe in hopes that the weather would help her arthritis.

In Maine she met the photographer Rudy Burckhardt and the painters Alex Katz and Rackstraw Downes, among others, and exchanged many visits with the painter Jake Berthot in Belfast. She withdrew somewhat from the commercial art world in the late 1990s, but she never stopped painting.

“If I’m not working,” she explained in the video interview, “I just feel like an unmoored crazy person.”