Garmin GPSMAP 4000 - Manual (Page 55)

GPSMAP 4000 Series Owner’s Manual 
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Understanding County Warnings
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.
Tornado Warning
Severe Thunderstorm Warning
Flood Warning
Flash Flood Warning
Viewing Forecast Information
Forecasts show the weather conditions including fronts and precipitation. To view the forecast for
another time period, select Next Forecast . The forecasted weather for the next 12 hours is shown.
Continue to select Next Forecast to view forecasts for the next 24, 36, and 48 hours. To view
forecast information for another location, press the ROCKER and use the map pointer ( ) until
the desired location appears.
Understanding Fronts
The Fronts show lines indicating the leading edge of an air mass. This feature also shows 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.
Cold Front
Warm Front
Stationary Front
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 North America.
Indicates a High 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 High Pressure Centers in North America.