Temperature forecasting is more challenging when it is not certain how much snow will be on the ground. The significance of a snow event will have important effects on the temperature forecast. During the day, fresh snow is a strong reflector of solar radiation. With snow on the ground (especially when the sun comes out after the event), the temperature will generally be much cooler than if there was no snow on the ground. During the night, snow insulates the ground below it and it is a good emitter of long wave radiation. Thus, the temperature at night tends to be colder as compared to when there is no snow on the ground. The temperature forecast will generally need to be colder if it is thought there will be a layer of snow on the ground. When the forecast changes from a non-snow event to a snow event, the temperatures will need to be adjusted toward colder values. If it is thought that there will be little or no snow, then generally the temperature forecast will need to be made warmer. If there is a snow event forecast that changes to looking like little or no snow will occur then the temperature forecast will need to be adjusted toward warmer values. One challenge lies in situations where in the 2 to 7 day forecast, that there is a chance for a significant snow event. Whether that snow event occurs or not will have a significant impact on the high and low temperature values. Keep this in mind when the forecast needs to be changed and keep in mind that not only is the snow event uncertain, but the high and low temperatures are uncertain also since they depend so much on the snow event occurring or not. |