Most of us would like to know what the weather will be for many reasons. We would like to know what to wear to an outdoor sporting event, or we may need to take appropriate action to save ourselves from potential severe weather. For centuries, humans developed various means for forecasting, including the rich weather lore that may or may not involve sound physical rationale. A major focus in modern meteorology entails the development of methodologies to make accurate forecasts of future weather events using proven scientific methods.
So how can we make a reasonable scientific weather forecast? We will consider just the next several days, since forecasts for more than several days are considered to be outlooks of general trends. Obviously, the easiest method would be to consult the local forecast prepared by the National Weather Service. Their forecasts are based upon an array of various "numerical weather prediction" models that are run on computers using weather data from surface weather observation stations, radiosondes and weather satellites.
If we were not able to receive a forecast, we could make a reasonable forecast. One method would be by "persistence", which assumes that the weather would remain the same or persist throughout the forecast period. In other words, if you step out and observe sunny skies and mild temperatures, you would make a forecast that these conditions would continue for the next hour or two. Often times this type of forecast would be reasonable for a short time, particularly if a large high pressure cell is nearby. The accuracy of this method decays rapidly with time.
Another forecast method would involve "climatology" , where the forecast is based upon some long term climatological average. In other words, you would forecast tomorrow's high temperature as being the same as the "normal" high temperature for tomorrow. This type of forecast may fail if an extremely cold or warm air mass moves into the your region.
We could also use single station forecasts, by watching the sequence of weather that evolves in combination with the looking at the current weather map. We have discussed how you can locate where the low (or high) pressure cell would be relative to you by facing downwind. Looking at the current weather map helps pinpoint the positions. We can also refine our forecast skills by looking for changes in the wind direction, cloud types, air pressure and air temperature over several hours, especially if a mid-latitude cyclone were approaching. Using your WeatherCycler or the description on pages 184-185 of Part A of the DataStreme Study Guide, you determine whether you will be on the warm side or cold side of the storm. In addition, you can look at a sequence of surface weather maps and attempt to extrapolate the movement of the weather systems that would cross your area.
For a description of how to read and interpret the Forecast charts on the DataStreme Homepage, you can read the optional Thursday Supplemental Summary Information .
To be submitted on the lines for Thursday on the Study Guide, Part B, Applications', Week 10 Chapter Progress Response Form, under section B. Daily Summary.