DENVER It was August 30, 2004 when Denver7 viewers first met Mike Nelson during the 5 oclock newscast.That first weathercast Nelson tracked scattered thunderstorms rolling through Denver in what would be the first of thousands of times Nelsons reassuring voice would help Coloradans navigate the many twists and turns of our ever-changing weather.Nelson will sign off Denver7 as chief meteorologist after more than 20 years leading the stations weather coverage and after over 40 years forecasting weather at television stations across the country.His final weather forecast on Denver7 will be on December 12.Denver7 opened up the video vault to find his very first appearance with longtime anchors Bertha Lynn and Anne Trujillo. You can watch Nelsons debut in the video player below. Watch Mike Nelson's first Denver7 weather forecast from 20 years agoNelson began his long career in 1976 with Weather Central, a Wisconsin-based consulting agency where he developed a transformative weather graphics system for television forecasts which led him to help install these systems at over 50 TV stations across the country.He became chief meteorologist at St. Louis CBS affiliate KMOV in 1985 before moving to Denver in 1991 becoming the lead weather forecaster at KUSA before moving to his home at Denver7 in 2004.Through his years at Denver7, Nelson has been a trailblazer covering and raising awareness on climate change and its impacts on Colorado weather, authoring The Worlds Littlest Book on Climate Change.Educating students about weather safety has been one of Nelsons passions through the years and he estimates hes spoken to as many as one-million school children during his career, including sharing his tornado dance with students.Weather has been my favorite subject since I was 7 years old, said Nelson. One of Nelsons earliest breaks came while he was working at a Baskin-Robbins Ice Cream store in Madison, Wisconsin. Nelson wrote he used to serve Madison TV meteorologist Terry Kelly ice cream and finally worked up the courage to ask Kelly for a job. I told him I would empty his trash and answer his phone for free, Nelson wrote.That tenacity paid off as Kelly eventually hired Nelson for his first taste of weather forecasting.As Nelson prepares to sign off from Denver7, you can follow his next chapter on his social media accounts. Its been a great ride and I love working with all of the people here, Nelson said during his retirement announcement.Longtime Denver7 morning meteorologist Lisa Hidalgo will succeed Nelson as chief meteorologist.