this shaking is because the weight of the body is holding the front end to the ground. the 1st and most logical thing to check is for excess front wheel bearing play. while weight is pressing down the bearing is likely pressing down on the lower race section of the bearing, but when weight is being drawn upward by the wind lifting the bearing attemt to self center and the excess play is felt in the form of a wheel shake. your alignment people didnt do a great job if they didnt check for this before aligning the front end. additionally tires not correctly ballanced can produce a higher speed shake but this would not be after topping a hill as described. have you checked you Mc pherson struts as well? I dont see them causing the whole described problem but they may be not having the return power to eliminate wheel hop once it does start. lastly but very important for everybody to know. tire designs inside the tire (the coards) are designed to allow flex but return to the original shape everytime. this is wonderful for a car that starts off with a perfect alignment and suspension. this is terrible for a car with a front end problem before the tires are installed and not repaired 1st. it actually accelerates wear to the tires after the alignment has been done. the reason is the treads form a wear pattern on all cars. like our shoes form a sole wear pattern that matches your pattern of foot preasure, heal wear, inside wear, ball of the foot etc. have you noticed that it wasnt only the sole that had a wear pattern? the outer or inner leather may sag to the side, the fear inside lining may be worn thru. tires wear in too! and if you have ever tried to wear someone elses old worn shoes be prepaired for cramps etc!
my web page www.mycarandineedhelp.com its free and its me if anybody wants answers like this