Stopping a function

i have a snow effect in a movie with the code below. i want to stop the effect midway through the movie without stopping the movie. how do i use a stop command to do this?

init = function () {

width = 550;
// pixels
height = 400;
// pixels
max_snowsize = 15;
// pixels
snowflakes = 125;
// quantity
for (i=0; i<snowflakes; i++) {

t = attachMovie("snow", "snow"+i, i);
t._alpha = 20+Math.random()*60;
t._x = -(width/2)+Math.random()*(1.5*width);
t._y = -(height/2)+Math.random()*(1.5*height);
t._xscale = t._yscale=50+Math.random()*(max_snowsize*10);
t.k = 1+Math.random()*4;
t.wind = -1.5+Math.random()*(1*3);
t.onEnterFrame = mover;

}

};
mover = function() {

this._y += this.k;
this._x += this.wind;
if (this._y>height+10) {

this._y = -20;

}
if (this._x>width+20) {

this._x = -(width/2)+Math.random()*(1.5*width);
this._y = -20;

} else if (this._x<-20) {

this._x = -(width/2)+Math.random()*(1.5*width);
this._y = -20;

}

}
init();