Weather Mapping

The weather map that appears in daily newspapers can be used to predict with some degree of accuracy conditions in the next few days. It usually does not include as much station information as the more detailed maps described above. Instead the major features of the daily weather map include isobars and high and low pressure areas.

Isobars connect locations with the same barometric pressure. The pressure described by each isobar is often indicated at one end, the other, or both, in inches, millibars, or other unit. Isobars often enclose regions of high or low pressure indicated on the map as H or L.

The outer edge of a concentric series of isobars marks a front. The nature of the front is indicated by means of solid triangles, solid half-circles, or a combination of the two. An isobar with solid triangles attached represents a cold front; one with solid half-circles, a warm front; one with triangles and half-circles on opposite sides, a stationary front; and one with triangles and half-circles on the same side, an occluded front. The daily weather map may also include simplified symbols that indicate weather at a station as a T enclosed in a circle for thunderstorms, F enclosed in a circle for fog, and Z in a circle for freezing rain.