Neon green cigar shape craft with neon red tail emission traveling noiselessly at high speed .

My coworker and I were standing out on a small balcony on the south side of our control room near the end of our shift as we often did. The night was very overcast and no moon or stars were visible. Our plant is very close to the Mississippi river at only 3 or 4 blocks away. A cigar shaped bright neon green craft with a long neon red emission at the rear dropped down through the clouds moving south right above the river as if to verify its course and just as quickly disappeared back up through the clouds. We slowly turned to look at each other. Each of us almost afraid to admit to each other what we had just seen. There was no noise and it moved very fast. The colors literally glowed like neon does. I have no idea what it was but you could tell it was a craft of some sort.
Witness indicates that date of incident is approximate.  PD