The young park ranger let out a whoop as her 13 chargesfollowed her up Dark Hollow Nature Trail just off Skyline Drive. Ranger Pat Momich, who had been conducting "discovery walks" every winter Saturday, had sighted her first sign of spring on Shenandoah Mountain.

"This is an exciting time," she told her listeners as they bent to inspect the tiny, white, liver-shaped flower, the hepatica. She had discovered it a few days earlier, she said, but a little farther on she spotted for the first time this year a coltsfoot, a tiny, yellow thistle. She got excited again.

Spring is just making its debut in the mountains, so we decided to make them the focal point of our first weekend trip of the year. Combined with an overnight stay at a mountain inn that is like visiting distant country relatives, it made for an extremely relaxing weekend.

Even at the height of the wildflower blooming, many of the signs of spring aren't visible from the car, so we took along hiking boots for a walk on one of the 20 hiking trails described in the large "Park Guide." We bought our copy from a machine for 50 cents after paying the $2 entry fee for our car at the Front Royal entrance of the Shenandoah National Park, 60 miles and 1 1/2 hours west of Washington.

The biggest advantages of taking the drive early are lack of traffic, nearly empty picnic grounds and the ease with which we could see how the now-leafless mountains such as Hogback, Old Rag, Flattop, Stony Man and Brokenback got their names. But traffic picks up in April. The U.S. Park Service counted 74,137 cars down the drive last April, compared to 109,362 cars last October, the peak time of the year when people flock to see the fall leaves.

Momich recommends mid-to-late April for persons wishing to see the spring wildflower explosion at its height. The "Park Guide" lists only three varieties out in March, but 18 the last third of April. Pink and white trillium carpet the meadow floor after mid-April, Pat said. On her discovery walks she offers such amusing tidbits as the Big Meadows area of the drive is the only place we could see a spotted skunk under a gray birch because those skunks aren't found any farther north and those birches aren't located any farther south.

We had made reservations at an inn we had heard about, and dinner was to be served at 6 p.m., so we turned off the drive at Swift Run Gap, where U.S. 33 crosses the drive. We headed west to Harrisonburg, picked up U.S. 11 and took it north to Mt. Jackson. We turned onto Rte. 263 at Mt. Jackson and took the undulating road west about nine miles until we saw a sign on the right: "Sky Chalet, the Friendly Mountain Resort."

It certainly is.

Elizabeth Wright, a white-haired widow in her 70s, not only owns and operates the Sky Chalet - she is the Sky Chalet. Our visit was well-timed. Wright had just returned the day before from her first trip away from the inn in nearly two years. She got away this time only because one of the frequent guest couples offered to spend a week's vacation running the place for her.

The food was unpretentious but home-cooked and good, including home-made bread. Drinks were nonalcoholic: Wright owns no liquor license. On this night, dessert was home-made ice cream, made in a manually cranked bucket and from Wright's recipe that keeps it creamy and free of ice.

Breakfast, at 8:30, and lunch, at 1 p.m., were equally good. Diners are summoned by a large bell atop a cottage next door, rung by a tug on a rope tied outside the kitchen door. A mother-and-daughter team (they also serve as maids for the 20 rooms in the complex) handles the meals. Wright spends dinner stopping at each table to chat. She is proud that she has at least one antique in each room. Ours had a Pennsylvania Dutch dresser and mirror.

After dinner as we went to get our luggage from the car, Wright suggested almost apologetically that we register as we passed the tiny reception counter. We realized only the next day that we were never given a key for our room. (The rooms to have a latch to lock each door from the inside.)

Most guests gather in the evening in the large living room where Wright chats and gladly answers questions about the inn and the area. For other diversion there are billards, Ping-Pong, shuffleboard, swimming, badminton, croquet and hammocks. When warm weather arrives the best part of the lodge will open. It is a huge semi-circular, two-level porch that overlooks Great North Mountain, behind which the sun sets. Several rockers sit on the upper porch just off the dining room.

After Sunday breakfast we said we wanted to walk over to Bryce to look around, so Wright directed us to a trail leading off in the woods along the top of Supin Lick Ridge. She said it would bring us out at the top of a ski lift and said we could return up the road from Bryce, but cautioned, "It's a right steep climb."

We walked it, found out Bryce would inaugurate grass skiing (on short, noisy, tractor-like treads) around Memorial Day and that the lowest rate at the condominium or townhouse there was $45 a night for a double during April, its "low season." That doesn't include meals.

On our walk back we stopped at the tiny Funkhouser family cemetery beside the road and read tombstones.

The room rate at the Sky Chalet is $35 a night at the lodge, $50 in a new A-frame that would be ideal for groups. The rate includes three meals for a couple.

There are three comfortable alternatives to taking the interstate back to Front Royal. We took the picturesque Fort Valley route, up Rte. 678. Since it was too early for the height of spring, it was too early for the height of the usual weekend flea market in Front Royal, normally a source of good buys.

This weekend the pickings were slim. But that allowed us to get away with a 300-mile, $50 (plus gas) early spring weekend.

Besides the two-hour discovery walk, every Saturday at 1:30 p.m., Skyline Drive also offers during April a one-hour Sunday stroll at 10:30 a.m. and a two-hour birding walk at 6:45 a.m. on Sundays, all from the visitors' center at Big Meadows. Skyline offers comfortably rustic accommodations at Skyland, which reopened on March 31. Big Meadows Lodge and Lewis Mountain cabins reopen April 28.

The Shenandoah Mountain is honeycombed with caverns along its western slope. Take your choioce from Luray, Shenandoah, Skyline and Grand, all reachable from Rte. 340 between Waynesboro and Front Royal, or Massanutten Caverns at the southern tip of Massanutten Mountain off Rte. 33.

For Skyline Drive information, call (703)-999-2211 or write Superintendent, Shenandoah National Park, Luray, Va. 22835. Pamphlets also are available at the Virginia State Travel Service at 906 17th St. NW in the District. The phone number for the Sky Chalet is (703)-856-2147, or write Mrs. Joseph A. Wright, Star Route, Mt. Jackson, Va., 22842.