THE PILOT SAID THAT WHILE ON A STUDENT SOLO CROSS-COUNTRY FLIGHT, SHE ENCOUNTERED SNOW SHOWERS, TURBULENCE AND MARGINAL VISIBILITY. A 180 DEGREE TURN WAS INITIATED TOWARDS A NEARBY AIRPORT, BUT AFTER LOSING ALTITUDE IN THE TURN, AND FIGHTING THE TURBULENCE, A PRECAUTIONARY LANDING WAS ATTEMPTED ON A RURAL ROAD. DIRECTIONAL CONTROL WAS LOST DURING THE LANDING ROLL AND THE AIRPLANE COLLIDED WITH A SNOWBANK AND NOSED OVER.