(Sub)Tropical Storm - May 27-28, 1988? 

Check it out. I was trying to find an image for Tropical Depression One in 1988, when I came across this, which looks like a well-organized unclassified storm just off of North Carolina. On May 26 a cold front extended across the western Atlantic Ocean. The next day, a circulation developed to the southeast of Charleston, South Carolina, with much of its convection sheared to the northeast; at the time, it might have still been frontal. Tracking to the northeast, by early the next day the center became more involved with the convection, though only based on interpolation from IR. By the time of the first visible image, it was just off of the Outer Banks of North Carolina, possibly extratropical or subtropical, based on the (presumably) cold air being entrained. Convection deepened, and three hours later it looked tropical, which is where I found the image. Unfortunately, there's no more Atlantic visible images after that due to an error. Nilfanion found this visible satellite image, meaning it must not have been very deep. Here's another, and here's a small one. Verdict? Probably an extratropical cyclone and maybe a subtropical cyclone that had some aspirations to do something.  (talk)