OverExposed Night Shot

I inadverdently Overexposed a lightning shot a couple nights ago .. if i tamper with the 'color' in a simple program like GIMP I can see the lightning stroke as a grainy blech in the photo.. is there any way in photoshop to turn down the exposure to a point where i can define the stroke of lightning in the shot or should I chalk it up to another in my long series of 'attempted lightning shots but not quite' .. any help would be awesome .. the big problem is usually when I shoot lightning I have my Canon set to RAW but for some reason I reset the dial in settings back to Large JPG so I believe the photo is going to be a toss out as we all know the limitations of jpg vs raw photos..


Thanks in advance :)