Surface Pressure And Water Temperature Data; Changing The Sea Surface Temperature Color Range; Visibility Information; Viewing Forecast Visibility Information For Another Time Period - Garmin GPSMAP 7400 Series Owner's Manual

Surface Pressure and Water Temperature Data

Surface-pressure information appears as pressure isobars and pressure centers. Isobars connect points of
equal pressure. Pressure readings can help to determine weather and wind conditions. High-pressure areas are
generally associated with fair weather. Low-pressure areas are generally associated with clouds and the chance
of precipitation. Isobars packed closely together show a strong pressure gradient. Strong pressure gradients are
associated with areas of stronger winds.
Pressure units are shown in millibars (mb), inches of Mercury (inHg), or hectopascals (hPa).
Colored shading indicates the surface temperature of the water, as shown in the legend in the corner of the
display.

Changing the Sea Surface Temperature Color Range

You can change the color range dynamically to view higher resolution sea surface temperature readings.
1 Select Charts > Sea Temperature > Menu > Sea Temperature.
2 Select an option:
• To allow the chartplotter to adjust the temperature range automatically, select Auto Configure.
The chartplotter automatically finds the lower and upper limits for the current screen, and updates the
temperature-color scale.
• To enter the lower and upper limits for the temperature range, select Lower Limit or Upper Limit, and enter
the lower or upper limit.

Visibility Information

Visibility is the forecast maximum horizontal distance that can be seen at the surface, as shown in the legend
on the left of the screen. Variations in the visibility shading show the forecast change in surface visibility.
NOTE: This feature is not available on all devices and in all subscriptions.
Select Charts > Visibility.

Viewing Forecast Visibility Information for Another Time Period

1 Select Charts > Visibility.
2 Select an option:
• To view the visibility forecast for the next 36 hours, in 12-hour increments, select
• To view the visibility forecast for the previous 36 hours, in 12-hour increments, select

Viewing Buoy Reports

Report readings are taken from buoys and coastal observation stations. These readings are used to determine
air temperature, dew point, water temperature, tide, wave height and period, wind direction and speed, visibility,
and barometric pressure.
1 From a weather chart, select .
2 Select Buoy.

Viewing Local Weather Information near a Buoy

You can select an area near a buoy to view forecast information.
1 From a weather chart, select a location on the chart.
2 Select Local Weather.
3 Select an option:
• To view present weather conditions from a local weather service, select Current Condition.
• To view a local weather forecast, select Forecast.
• To view surface wind and barometric pressure information, select Sea Surface.
• To view wind and wave information, select Marine Bulletin.
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multiple times.
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