Meteorologists use many tools to predict the weather. They use past data such as temperature observations, real-time data such as radar and satellite images, and models that look into the future. Many different parameters are plotted using the numerical forecast models, which are generated using computers. The models consist of numerical equations which use current conditions as the inputs. The resulting outputs are forecasts for what is likely to happen in the future, based on those initial conditions. There are many different models that all attempt to do the same thing. The Global Forecast System model is used in this visualization.
The predicted amount of snow accumulation on the ground is shown in these images, taken from the latest NOAA Global Forecast System weather model. Areas colored blue have the deepest snow amounts; white areas have light snow accumulation; transparent areas are snow-free. The Global Forecast System is NOAA's main weather model and is used by a variety of other private sector groups involved in providing weather information. The model runs every six hours and provides weather predictions for 10 days (240 hours) out from the start time, in three-hour time increments.