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The Fronts feature displays lines indicating the leading edge of an air mass. This feature also displays pressure centers. Pressure
centers are represented by a large Red “L” for low pressure centers or a large Blue “H” for high pressure centers. Pressure centers
represent an area where pressure is measured to be either the highest or lowest relative to the surrounding area.
Occluded Front Trough
Indicates a Low Pressure Center. A Low Pressure
Center is an area where the measured pressure is
lowest relative to the surrounding area. Moving
away from a Low Pressure Center in any horizontal
direction results in increased pressure. Winds ﬂow
counterclockwise around Low Pressure Centers in
Indicates a High Pressure Center. Similar to a Low
Pressure Center, a High Pressure Center is an area
where the measured pressure is highest relative to
the surrounding area. Moving away from a High
Pressure Center in any horizontal direction results
in decreased pressure. Winds ﬂow clockwise
around Low Pressure Centers in North America.
XM WEATHER FEATURES > FRONTS
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15 GXM 30 XM Radio Smart Antenna Owner’s Manual
Visibility is the forecast maximum horizontal distance that can be seen at the surface. Contour lines on the Visibility feature show
the forecasted change in surface visibility. In the example below, visibility ranges from 1 miles to 4.5 miles.
Visibility Contour LinesThis image displays NEXRAD Radar, Satellite
Mosaic, and Visibility. Displaying multiple
features may help to provide a clearer picture of the weather conditions in the area.
XM WEATHER FEATURES > VISIBILITY
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When the National Weather Service issues a weather warning for a county, the county is highlighted with the color corresponding to
the warning. To view information about the warning, select the county with the map pointer. For more detail, press
Severe Thunderstorm Warning
Flash Flood Warning
Severe Thunderstorm Warning
XM WEATHER FEATURES > COUNTY WARNINGS
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17 GXM 30 XM Radio Smart Antenna Owner’s Manual
The Water Temperature feature displays the water’s surface
temperature. The temperature breaks are indicated by isotherm
The Wave Period feature provides the time (in seconds)
between successive waves.
Water Temperature Wave Period
XM WEATHER FEATURES > WATER TEMPERATURE AND WAVE PERIOD
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The Wave Direction feature shows the direction in which a
wave is moving, as indicated by the direction of the red arrow.
The Wave Height feature displays wave heights. The wave
heights for an area are separated by contour lines.
Wave DirectionWave Height
XM WEATHER FEATURES > WAVE DIRECTION AND WAVE HEIGHT