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How-to GRIB Meteorological data

GRIB, the 'General Regularly-distibuted Information in Binary form', is a file format for storing historical and forecast meteorological data.
Qastor can use these files to show a weather overlay, generate forecasts for certain locations, and graph predicted conditions along a planned route.

On this page:


On startup, the folder "grib" in the project's Support folder is checked for any grib files. The recommended way to keep this folder up to date with the latest forecasts, is to let Connect synchronize the contents with an online weather service. Alternatively, the files could be downloaded, unzipped (depending on the provider), and copied to this folder manually. When doing this, it is important to delete the old files, to make sure there are no ambiguities between the available forecasts.

If any forecast data is available, the application will look like this on startup:

If there is GRIB data available, but all forecasts are in the past, the following screen is shown:

If this is the case, it is advised to use Connect to synchronize the Support folder, or to download a new set of GRIB files by other means.


Click at various points in the navigation screen and in the controls of the overlay menu to watch the values change.

MinimizePress the downward facing arrow to minimize the control panel.
Time and date

The currently displayed forecast time.

ForecastThe wind direction and speed, air pressure, wave height, current, rainfall and temperature under the cursor in the navigation screen.
To the right, the forecast is shown for 3, 6, 12 and 24 hours after the display time, to give an indication of trends.
SliderClick in the horizontal bar to set a new displayed time and date.
If a route is already loaded then the left end of the slider is the current time and the right end of the slider is the time of the last available forecast.
If no route is loaded then the left side of the slider shows the first available time in the forecast.
A small vertical line is drawn for every midnight.
No overlay data is shown.
If you would like to show the overlay again, press the  button to activate it.
Only pressure lines and wind barbs will be shown.
If you would like to show the overlay again, press the  button to activate it.
Layer selectionUse this button to switch between different display modes. These are "wave""rain", "wind" and "current".

Route planning

While a route is selected, the control panel changes to show the forecasts along the route:

Switch panelSwitch between the Controls panel and the Route forecast panel.
Cursor infoShow the date, time, and forecast of the cursor.
Min / MaxThe minimum and maximum values of the wind speed, wave height, and rainfall along the route.
Departure timeThe planned departure time. This can be changed by clicking on this field. A dialog will open to adjust time and/or date. (See below.)
In Planning mode you can view the departure time at the left of the time line.
In Navigation mode the time line starts at the current time and cannot be adjusted.
CursorHovering over the graph with the mouse will show a vertical orange line. The cursor info will show detailed information about this point in time.
The cursor can be seen to move along in the navigation screen, showing the wind, wave or current direction on the route.
WaypointThe waypoint names and their estimated times of arrival are shown underneath the graphs.
Wind speedA graph shows the expected wind speed along the route.
Wave heightA graph shows the expected wave height along the route.
RainfallA graph shows the expected rainfall along the route.

Changing the departure time/date:

Note that the forecast data may not cover the entire route.
If this is the case, the graphs will not extend all the way to the last waypoint line on the right side, or will be missing altogether.