I found a timeline similar on Intellistar's Wikipedia page, but there wasn't a whole lot of info relating to the satellite local forecasts. You can add to it as needed, and even the tiniest changes can be added.
I'll start out:
June 2004:
-The graphics are updated for the entire forecast. This includes the removal of the current conditions from the metro forecasts.
July 2004:
-The LDL is added to TWC for satellite viewers, specifically DirecTV at this time. It cycles through the sky/temperature conditions, airport delays, and forecasts for all of the cities seen on the "3 day forecast" segment.
September/October 2004:
-The south central, northwest, and southwest radar/satellite loops are added to the local forecasts.
-I'm not sure on this, but wasn't Houston and Dallas/Ft. Worth added to the metro forecasts at the beginning at this time?
August 2005:
-A whole new graphics package for the satellite local forecast. This includes the addition of more cities on the metro forecasts (Minneapolis, Orlando, Miami, Denver, Phoenix, Sacramento, Seattle)
September 2006:
-The satellite LDL is added to TWC for Dish Network viewers.
December 2006:
-Icons are replaced with newer ones on the satellite local forecast, as with the Intellistar
NOT SURE ABOUT THE FOLLOWING: (I believe this was sometime between the redesign in August 2005 to December 2005)
-Additional cities are added to the LDL that are not seen on the 3 day forecasts (Omaha, Honolulu, Albuquerque, and I can't think of any others at the top of my head)
