The National Park Service is hoping Washington will have a mild winter.

The reason: Congress left town without appropriating enough money to repair Union Station's badly leaking roof.

Congress did at one point approve a $6.5 million appropriation for the roof, but those funds were struck from the final money bill passed by both houses before adjournment.

The roof will not cave in, Department of Interior officials said yesterday, because the agency already has begun to make some repairs with funds it received earlier this year from the Urban Mass Transportation Administration.

The badly leaking roof, which has endangered ceilings and rotted floors throughout the 73-year-old granite building, needs about $8 million in roof repairs alone, according to the National Park Service. The Park Service is maintaining the old train station as a partially finished National Visitor Center, until Congress decides what to do with it.

"We've got people repairing the gutters and downspouts and the station's domed roof but we don't have enough money to work on other parts of the roof," said Park Service spokesman George Berklacy. "Let's hope it doesn't rain or snow too much this winter."

Senate and House public works committee staffers yesterday predicted that Congress will fund the additional $6.5 million needed to repair the roof, probably some time next spring. The future of the rest of the building, however, still is in doubt.