# `wx` - a command line interface for aviation weather

`wx` fetches weather data from the NOAA Aviation Weather Center's Text Data
Server (TDS).

## Installation from source

1. Clone the repository
2. Run `sudo make install`

## Usage

Currently, we support fetching METARs in a variety of methods. When fetching
METARs, a time constraint must be supplied. A time constraint can either be in
the form "past x" or "between x and y".

    $ wx metar --past 3h
    $ wx metar --since 2020-01-01T00:00:00 --until 2020-01-02T00:00:00

The `--past` argument defaults to `1h`, so if none of `--past`, `--since`, or
`--until` are specified, METARs from the past hour will be fetched.

Note that the TDS only stores METARs from the past three days, so the `wx`
command cannot effectively be used to pull historical data.

### For a set of stations

You can fetch METARs from a set of stations by their full or partial ICAO IDs:

    $ wx metar kbos
    $ wx metar kbos ksea
    $ wx metar kb

### For stations in a region

You can fetch METARs from all stations within a rectangular or radial region.
Rectangular regions are specified by a `minLat,minLon,maxLat,maxLon` tuple:

    $ wx metar --rect 39,-70,40,-71

Radial regions are specified as a radius in statute miles around a center point
as a `dist,lat,lon` tuple:

    $ wx metar --radial 5.5,40,-70

### For stations along a flight path

You can fetch weather for all stations with a distance of a specified flight
path. A flight path is specified by a series of `--waypoint` arguments, where
each waypoint can be an ICAO identifier or a `lon,lat` tuple. Waypoints must be
specified in order from origin to destination.

    $ wx metar --path-dist 10 --waypoint ksea --waypoint kbos

### Controlling density

When running a query which will return METARs from many stations, it may be
helpful to reduce the density of the results. This can be done with the
`--min-dist` argument which specifies a minimum distance (in degrees of latitude
or longitude) between stations to display. Providing a higher value for
`--min-dist` will result in fewer stations being returned.

    $ wx metar \
      --path-dist 10 --waypoint ksea --waypoint kbos \
      --min-dist 5 \

### Filtering recency

There are two mechanisms for filtering results by recency. First, you can
request the single most recent METAR from all the stations being fetched:

    $ wx metar --past 6h kbos ksea --most-recent

Even though we've specified two stations, KBOS and KSEA, we'll only get a single
METAR back from whichever of the two stations most recently made an observation.

The second filtering mechanism is `--most-recent-by-station`. This argument can
take several values:

* `constraint` (default): request the most recent for each METAR station in the
  fastest fashion.
* `postfilter`: filter results after applying all other constraints.
* `false`: don't filter results to only the most recent for each station.

## Contributing

Email patches to <mailto:~benburwell/patchall@lists.sr.ht>.

## License

MIT