Async Push data to Array in Node

I'm calling mongoose query inside of another mongoose query. When I push results to a array, When ever I check it at last it is empty. After seacrching a lot, Found that issue is this executes asynchronously. But can't find how to fix the issue. My code is as follows.

    Bus.find().exec(function(err,buses) {

        if(err)
            console.log(err);
        if (buses[0] != null){
            const cords = [];
            buses.forEach( function (bus) {
                // console.log(bus);
                    Position.findOne({"busId": bus.busId},{}, {sort : {'time' : -1}}, function (err, position) {
                        cords.push(position);
                        console.log(cords);
                        // console.log(position);
                    });
                    console.log(cords);
                },
                function (err) {
                    if (err){
                        console.log(err,"Errrrrrrrrrrrrr");
                    }
                });
            console.log(cords);
            res.json({cords: cords});
            }

via HelpingHand