"Tri-State Weather" was a segment that only satellite and New York City area cable subscribers saw (except in erroneous situations). It debuted in October 1987 and aired at 4:57, 5:27, 5:57, and 6:27 pm every evening.
At the same time, the three minute local forecast debuted. Viewers that didn't see the segment got the extended local forecast.
I haven't come across a promo announcing the debut of the segment, but I do have one announcing the debut of the new local forecast, as well as some promos. I also have an example of the segment, in case you've never seen it.
Here are the video clips I mentioned above.