Garmin 640 Guida Utente

Marine Mode: Using XM WX Weather and Audio

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 the 

lowest relative to the surrounding area.

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.
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.

City forecasts appear as standard weather symbols. The forecast is 

viewed in 12-hour increments for the next 48 hours.

Sea Conditions provide surface conditions including winds, wave 

height, wave period, and wave direction.