The purpose of this article is to explain advances in technology and algorithms to help improve forecast accuracy. It will compare forecasting methods from decades ago with forecasting methods used today. By explaining how errors can accumulate over time and providing simple mathematical formulas as examples, this article aims to show how repeating minor errors can affect the accuracy of weather forecasts.IntroductionTo In the era of Thomas Jefferson and George Washington, weather observations were recorded daily but not hourly or minutely. Such repetition of data did not seem useful. After the invention of the telegraph, which allowed information about weather data to be transmitted across the country, they still only reported once a day. Unlike today's virtual weather world, the 24/7 use of climate data from satellites, buoys in the oceans, the ability to record global temperatures, precipitation records worldwide, to track wind speed, solar wind pressure pulses, carbon dioxide levels, tornadoes and hurricanes... etc. (Harris, 2012). An early pioneer in meteorology was Vilhelm Bjerknes and his son Jacob, who described the life cycle of the extratropical cyclone and shared his ideas for scientific weather forecasting. Bjerknes was disappointed with the unscientific methods of meteorology of the time, which, in contrast, made accurate predictions in astronomy and meteorology, as he felt, had stalled. Its goal was to introduce scientific concepts to meteorology. According to Bjerknes, the two main ingredients of weather forecasting were knowledge of the atmosphere and precise knowledge of the physical laws that govern it. Bjerknes tagged: pressu...... middle of paper ......Went Wrong?.ncep.noaa.gov/nwp50/Presentations. Accessed February 19, 2012, from www.ncep.noaa.gov/nwp50/PresentationNOAA Earth System Research Laboratory. (nd). NOAA Earth System Research Laboratory. Accessed February 18, 2012 from http://www.esrl.noaa.gov/Vanorsow. (July 17, 2010). The Teaching Company User Community: View topic - 23. Prediction and predictability. The Teaching Company User Community: Index. Retrieved February 18, 2012 from http://teachingcompany.12.forumer.com/viewtopic.php?t=3034 Weather Modeling and Forecasting. (May 16, 2011). NOAA Office of Oceanic and Atmospheric Research. Retrieved February 17, 2012 from http://www.oar.noaa.gov/weather/t_modeling.htmlThe Weather Research&Forecasting Model Website. (nd). The Weather Research and Forecast Model website. Retrieved February 18, 2012 from http://wrf-model.org/index.php