The purpose of this article is to explain the advances made in technology and algorithms to help improve the accuracy of forecasts. It will compare forecasting methods from several decades ago with forecasting methods in use today. By discussing 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. Introduction In the days 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 on weather data to be transmitted across the country, it continued to be reported only once a day. Contrast this with today's virtual world of weather, which makes 24/7 use of climate data from satellites, buoys in the oceans, the ability to record world temperatures, world rainfall records, monitor wind speed, solar wind pressure pulses, carbon dioxide levels, tornadoes and hurricanes... etc. (Harris, 2012). One of the early pioneers of 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 by the unscientific methods of meteorology of the time, which, on the contrary, made accurate predictions in astronomy and, in his opinion, meteorology was at a standstill. His goal was to introduce scientific concepts into meteorology. According to Bjerknes, the two main ingredients of weather forecasting were knowledge of the atmosphere and accurate knowledge of the physical laws that govern it. Bjerknes identified: pressu...... center of paper......Wrong?.ncep.noaa.gov/nwp50/Presentations. Retrieved February 19, 2012, from www.ncep.noaa.gov/nwp50/PresentationNOAA Earth System Research Laboratory. (n.d.). NOAA Earth System Research Laboratory. Retrieved February 18, 2012, from http://www.esrl.noaa.gov/Vanorsow. (2010, July 17). The educational company user community: View topic - 23. Forecasting and predictability. The educational company user community: index. Retrieved February 18, 2012, from http://teachingcompany.12.forumer.com/viewtopic.php?t=3034Weather Modeling and Prediction. (2011, May 16). 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. (n.d.). The weather research and forecasting model website. Retrieved February 18, 2012, from http://wrf-model.org/index.php