WAS DRIVING AN 05 FORD FOCUS ZXW IN LIGHT RAIN AT ABOUT 40 MPH GOING UPHILL ON A MAJOR ROADWAY (55MPH SPEED LIMIT). VEHICLE IN FRONT BY ABOUT 40 FT STOPPED AND I HIT THE BRAKES. UPON HITTING THE BRAKES THE VEHICLE SEEMED TO START A GRADUAL SLIDE AND NEVER ALLOWED ITSELF TO REGAIN TRACTION.