Families are invited out to western Maryland on Saturday for winter frolicking at Herrington Manor State Park. Two cross-country ski races, for adults and kids, are featured events, if you're there by 9:30 to register. Otherwise, bring whatever equipment you want to use on the park trails. Picnic tables are available in a warm-up cabin. To get to the park from I-270, take I-70 at Frederick. It becomes U.S. 40 at Hancock; follow 40 to U.S. 219 South to the Deep Creek Lake area. There'll be signs to the park. The ride takes about three hours. For a snow double check, call 301/334-9180.

Cross-country skiing brings with it all sorts of questions: Waxless or waxable skis? Where to go around here? A program at Potomac Overlook Park, in North Arlington, will try to answer some of them. It's Sunday at 2. Call 528-5406.

For those who'd prefer exercise sans sliding, the Center Hiking Club will walk along the new Washington and Old Dominion Trail on Saturday. Meet at 9 at the Rosslyn Metro (on the corner of North Fort Myers Drive and 19th Street) for an easy eight-mile walk along the W & OD. It costs $1.75. For more information, call 931-7158 or 379-0460.