In November of 1963, H.D. was asked to be the on-air meteorologist at a new TV station – WHNT-TV. While still working for the ABMA, he took the part-time job at the station, and made his television debut Thanksgiving Day. This made him the first TV meteorologist in the history of the city of Huntsville. In 1972, he retired from the ABMA and became a full time meteorologist at WHNT-TV. During this time, H.D. quickly earned a reputation as a knowledgeable and well respected weatherman. He was well known around north Alabama for his calm, but straight-forward delivery. It made people realize that he was sincere about his job, and as a result they would listen intently to him. One of the most memorable things about Mr. Bagley was the way he would end his broadcast on the Friday night news. He would say, "Have a good weekend and wherever you go, go to church on Sunday."

While serving the residents of north Alabama as an on-air meteorologist, H.D. had his share of opportunities to save lives. And save lives, he did. On the night of April 3rd, 1974, H.D. was on the air, giving regular updates on violent severe thunderstorms and tornadoes tearing across the Tennessee Valley. He tracked the storms with an old radar that had been designed for use on a ship. It was archaic in terms of technology, but he used it the best he could to show his viewers where the storms were. Shortly after 9 PM that night, many of the storms had already died out or moved out of the area. Over fifty lives had already been lost in north Alabama, and over 500 had been injured. There was still one tornado left on radar. It was being produced by the very same storm that wiped out the town of Guin. The twister ravaged Redstone Arsenal, and took aim on the city of Huntsville. H.D. was still on air giving the latest updates to the people of Huntsville. He decided to step outside the studio to take a look at the storm. When he saw the tornado rolling across the city, he ran back into the studio and told everyone to leave the station and get in a ditch. The tornado missed the station by less than a mile. Remarkably, despite the fact that the tornado went straight through the city at night, no one perished. It would be difficult to think of what might have happened that night had there not been an H.D. Bagley on the television.

It was sixteen years that H.D. was on Channel 19. Over that period of time, he was proud of the fact that he was a straight-shooting and level-headed meteorologist. He was once chairman of the North Alabama Meteorological Society, and he also held the American Meteorological Society's Seal of Approval. H.D. retired on May 31, 1979 on his 62nd birthday and left his audience with this last statement — “Wherever you go the rest of your life, go to church on Sunday."