Fortunately, if conditions are poor in the Banff area, there are some great alternatives where you may find plenty of snow. Here are some ideas to hedge your bets:
1) In the Banff area, Sunshine is really worth the visit - a beautiful place and generally has slightly better snow than Lake Louise (http://www.skibanff.com/
2) From Banff you can also drive south to Fernie (http://www.skifernie.com/gettinghere/#
) which often has significantly better conditions than Louise.
3) Ditto for Red Mountain, http://www.ski-red.com/site/index.php?id=395.
4) Another option is to drive to Kicking Horse in Golden (west from Banff). http://www.kickinghorseresort.com/