Stack Opacity During Rain

[swb11]

During heavy rain events in the afternoon on hot days we get opacity spikes. We have added heaters to the purge air of the opacity monitor, but still see opacity during rain events. Using PI we see temperature swings which would explain, but we also see similar temperature swings without opacity fluctuations at other times. Has anyone had these problems if so what operational / equipment changes have you made and did they eliminate or minimize the problem. Also what type of environmental regulatory correspondence have you had?