The 24-Hour Difax map shows the 24 hour forecast for surface pressure and 1000-500 thickness. Atmospheric pressure is the pressure at any given point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Low pressure areas have less atmospheric mass above their location, whereas high pressure areas have more atmospheric mass above their location.
More Difax Maps
View the 48hr Difax Map »
View the 72hr Difax Map »
The WSI SuperFax image shows the current isobar analysis. An isobar is a line of equal or constant pressure on a graph, plot, or map; an isopleth or contour line of pressure. The line is formed by connecting points of similar pressure measured at different locations in a geographical area. In meteorology, the barometric pressures shown are reduced to sea level, not the surface pressures at the map locations. The distribution of isobars is closely related to the magnitude and direction of the wind field, and can be used to predict future weather patterns.