My brother used to have a taurus that did the same thing and i think we came to the conclusion tha there was snow or ice frozen on the wheel which will make it vibrate.. just a thought

'98 CSVT T-Red: K&N High Flow,Ford Racing 9mm wires,OMP STB,Fidanza short shifter,OEM High Flow MAS,Autometer Phantom Gauges,Magnaflow Resonator no Mufflers '01 400EX: some mods!!