Garmin G500 Pilot's Manual page 213

Surface Data Time
The Surface Data Time option allows you to select the forecast time when the
Surface and City Forecast weather products will appear on the selected MFD Wx
Data Link Map page (1, 2, or 3). Forecasts are available for intervals of current,
12, 24, 36, and 48 hours. You may also select an interval by pressing the SRFC
TIME soft key on the Wx Data Link Map page.
Figure 4-47 Surface Data Time Selection
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190-01102-02 Rev. E Garmin G500 Pilot's Guide