At low level it would be correct to say that you would be flying into an area of surface high pressure, and baro error would be in the safe sense, altimiter underreading, height increasing.
This is a slightly deeper question, as it says you are flying on the 500hpa level, i.e. about 18,000ft. Up high you have to take into account temp error as well. You are flying on the 500hpa contour, and if the wind is from the right it means you are flying into an area where the contours are higher amsl, so your height is increasing. You do not know whether this is because surface pressure is increasing or because the air mass temp below you is increasing. Either or both could be the answer.
Dick W