1998 Ford Station Wagon smoking front end intermitten

Engine Performance problem
1998 Ford Station Wagon 6 cyl Automatic 99000 miles

I have a Ford Tauras Wagon 1998 intermittenly I have smoke coming from the front end of the car mostly during wet and snowy days. I pop the hood and cant find where it comes from. Nothing is leaking from under the car. What could be the problem.