Bearing in mind that the experts on here say the forecast is not reliable beyond 3 days and also that this site seems to give town forecast and not the slopes.... this site might help you decide what to pack - be warm! It might also make you smile....I can't wait! Anyone elso going from Gatwick to Plov on the 18.15 flight?
http://wwwa.accuweather.com/world-forecast-15day.asp?partner=accuweather&traveler=0&locCode=EUR|BG|BU001|BANSKO&metric=1