3 GXM 30A XM Radio Smart Antenna Owner’s ManualSurface PressureThis feature displays pressure isobars and pressure centers. The isobars connect points of equal pressure. Pressure readings can helpdetermine weather and wind conditions in an area. High pressure areas are generally associated with fair weather. Low pressureareas are generally associated with clouds and the chance of precipitation. Isobars that are packed closely together show a strongpressure gradient. Strong pressure gradients are associated with areas of stronger winds. Pressure units can be displayed in Millibars(mb), Inches of Mercury (in), and Hectopascals (hPa).Strong Pressure GradientPressure IsobarsXM Weather features > surface Pressure