You hear me say all the time that our latest guidance will show something different from before. What I'm referring to are the computer forecast models that we look at several times a day.
Weather data from around the U.S. is gathered by weather balloons, satellites, radar and even airplanes constantly each day. All of this data is then sent to a super computer in Washington D.C., that takes the current data and extrapolates it into the future. Hours, days, and less accurately, weeks into the future.
There are several different calculations made with the data resulting in several different models to look at. All have strengths and weaknesses, so blending them is a common practice when they disagree on what might happen.
You may wonder why one weather person may say something different from another. We all look at the exact same data, but we all may interpret it differently.
The computers are accurate up to 70% to 80% of the time. The trick for us is to know when they are "out to lunch" so we can prepare the forecast all on our own. A daunting task at times.
Watch the attached video for more on models and see an actual weather balloon used to record upper air data.