CHAPTER EIGHTEEN - LOCAL FORECAST STUDIES

Abstract

Some of the classic concepts of certain meteorological phenomena are not well adapted to forecasting treatment. Among these are the customary treatments of advection and radiation fog. When fog forms on a clear night, it is easy to think of it as a radiation fog, for it is clear that the radiative heat loss of the earth's surface, which in turn cook the adjacent layers of air, has played a leading role in the formation of the fog. However, if one attempts to devise forecasting methods for this type of occurrence, it becomes quickly evident that for those locations that are within about 200 miles of an extensive body of water, the past history of the air in which the fog forms must be taken into account. This chapter highlights the causes of the two primary causes for such fogs. It discusses some factors that are favorable for fog formation. They are: (1) an extensive rain area with clearing at night, (2) wind deceleration, (3) a weak or dissolving front, (4) air blowing across colder water, then over land, (5) a drift of air off any extensive water surface, (6) past fog in the area, and (7) air with dew points above freezing blowing over a snow cover. Although, most of them are automatically included in the techniques for various localities, it is impossible to do so completely and the forecaster must be aware of this. The standard method for forecasting the time of formation of radiation fog is the same at all localities and will not be repeated in each study.