SHORTLY AFTER her first one- woman show, "What a Farmwife Painted," in 1940, Grandma Moses appeared at a Gimbel's Thanksgiving Day festival to address her new-found public. The department store was exhibiting her work -- naive paintings of farm landscapes that were to become hallmarks of Hallmark.

Not knowing what was expected of her, Grandma Moses spoke about preserves.

She was everyone's fantasy grandmother, active to the age of 101. What's touted as the largest major show since her death in 1961 is now at the Baltimore Museum of Art. This being the season to go over the river and through the woods to grandmother's house, if only in memory and imagination, we can appreciate the paintings as so many season's- greeting cards.

Grandma Moses painted white and drifting snow, and turkeys being chased for supper. She liked covered bridges and the excitement of a good thunderstorm.

The paintings depict someplace nice -- often upstate New York, 19th-century or thereabouts -- busy with friendly people of no particular identity, seen in flat perspective. Though the paintings were done mid-20th century, cars never clutter them, and no power lines scratch their skies.

In "Evening," her unusual perspective enhanced the subject to a remarkable degree: Grandma Moses captured that ghostly twilight when snow covers the ground and grey clouds hang low, diffusing the fading light and flattening the land. This painting of a farm in early evening, its old mill by a frozen stream, fills us with a longing to hurry into the house before the cold winter night.

To engage us further, in the foreground of her paintings there is often a boy in a cap waving toward the viewer, or two youths showing the maple sugar in a vat, or a woman pausing to look up as she hangs her wash.

Besides the 55 paintings, exhibited are some of Grandma Moses' source materials: the 1872 Currier and Ives print which she modified for "Sugaring Off," and some clippings from her personal archive of illustrations that she copied while teaching herself the rudiments of drawing and composition. There is also a fine piece of embroidery, "The Covered Bridge," which she did in 1918, before she discovered painting.

Though self-taught, she evolved her own style and developed as a painter. It's been said that her later paintings show tighter composition and tend to the abstract, perhaps heralding a sophistication. But at the same time, we note, Grandma Moses couldn't resist sprinkling a little silver glitter on the snow.

THE WORLD OF GRANDMA MOSES -- At the Baltimore Museum of Art through January 6, 1985. Art Museum Drive, off North Charles Street above 29th Street. Tuesday-Friday, 10 to 4; Thursday evenings, 6 to 10; weekends, 11 to 6. Admission $2, over 18. Free admission Thursdays. 301/36-6310.