What is it?
A forecast of atmospheric/air pressure.
Who is interested?
Shippers, carriers (fleet and drivers managers), brokers
What does it tell me?
Pressure is expressed as the average forecast atmospheric pressure in millibars (mb) in a certain freight Key Market Area (KMA) for the next 48 hours. This is updated hourly. Sharp decreases in pressure often indicate impending inclement weather.
Atmospheric pressure is the pressure exerted by the atmosphere at a certain point as a result of gravity acting upon the "column" of air that lies directly above that point. Consequently, higher elevations above sea level experience lower/less pressure since there is less atmosphere above these areas. Put another way, the weight of the atmosphere decreases with increases in elevation. Consequently, in general, for every 1,000 feet of elevation gain, the pressure drops about 34 mb. For example, locations near 5,000 feet above mean sea level normally have pressures around 813 mb. The mean global sea level pressure is around 1,012 mb.