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Weather Widget

A small set of python and bash utilities to retrieve radar images and the text of the Hazardous Weather Outlook for a given region from the US National Weather Service. On Mac OS X, these scripts integrate nicely with GeekTool desktop widgets. On linux, these resources can be nicely incorporated to a tabler (based on Angular.js) dashboard/webpage.

Prerequisites

Python, and either bash or zsh. I have no idea if this works on the Windows 10 bash interpreter. ImageMagick is also required. This codebase is generally intended for Mac OS X and Linux, but obviously there are Windows versions of all of this software, but I don't regularly use Windows. Erik Flowers's weather icons

Quick Start

  • Install prerequisites, if needed (requests and bs4 for python; ImageMagick libraries)
  • Change three variables in the Python script
  • Make sure the hard-coded paths to the convert binary are correct (might be /usr/bin/convert, might be /opt/local/bin/convert, might be something else)
  • If you don't have any cities larger than 1M people nearby, change the name of the weather station City_xxxx_Short.gif file in merge_backgrounds.sh
  • Put the bash and python scripts into a directory on your PATH
  • Run the python script once, manually, to ensure that everything works and to get the background images you need to have
  • Run merge_backgrounds.sh to make composited background images for the radar images
  • Set up the GeekTool widgets, if desired
  • Set up the periodic execution of the scripts with cron or launchd

Python

The codebase has a library of functions, classes, and methods, held together with some glue in main(). For locations other than Fort Worth / DFW, the end-user will need to change numerous abbreviations in the YaML settings file, including: one for the weather forecast office, one for the radar station , and one for the local conditions station abbreviation.

More recently, functions have been added to gather forecast information from the NWS web API

and hydrologic information from the NWS Advanced Hydrologic Prediction Service.

The YAML settings file does require a lot of abbreviations and such, but it's all pretty well contained in that one file. (Exception: merge_backgrounds.sh still hasn't been adapted for the settings file)

Basic program flow:

Python

  • Check for some required background images and gets them if needed.
  • Retrieve current conditions
  • Get the radar image (currently b0rked, because the NWS changed how they distribute weather radar data in December 2020)
  • Get the warnings image ("boxes" for overlaying)
  • Get the Hazardous Weather Outlook and parse it
  • Check for weather alerts
  • Get the weather forecasts and parse them
  • Get the hydrologic graph for the local river gauge, if any
  • Write out files to /tmp/ (or where specified in the settings file)

bash

  • Run the python script
  • Check for an overlay graphic (used in compositing the radar image)
  • Clean up the last observations
  • Use ImageMagick to composite the current radar image and backgrounds
  • Make a radar animation of up to the last 20 radar images

Limitations

The National Weather Service API currently lists only one endpoint as valid, the https://api.weather.gov/alerts endpoint. As of this writing, the "current observations" also works, though I do not know if the coverage is universal.

Setting Up Scheduled Jobs

Mac OS X

Before the first run, the end-user must modify the plist. There are sensible defaults but the path to the scripts must be set before it can run successfully.

Troubleshooting note: I found that the scripts don't necessarily have access to a PATH variable -- meaning the absolute paths must be specified for everything.

Put the getweather.plist file into ~/Library/LaunchAgents/

If you have already done this once, you may need to unload the plist first.

launchctl unload ~/Library/LaunchAgents/getweather.plist

launchctl load ~/Library/LaunchAgents/getweather.plist

To use GeekTool, one must also set up a widget ("geeklet").

Linux

Add a line to /etc/crontab and be sure that the end of the file contains a blank line, or else the last line of the file won't be parsed. The line might look like this (though using root is a terrible idea and that's an issue I will fix):

# Get weather radar a minute after the image is scheduled to appear:
3,6,10,15,19,23,27,35,38,43,47,51,55,59 * * * * root  /opt/weatherwidget/getweather.sh

That other Geeklet

In case you're curious (one person was) about the "Time Zones" geeklet seen in the desktop screencap, the bash command is this:

echo "Mtn View:   $(env TZ=America/Los_Angeles date +'%l:%M %p %A')";echo "Dallas:     $(env TZ=America/Chicago date +'%l:%M %p %A')";echo "Boston:     $(env TZ=America/New_York date +'%l:%M %p %A')";echo "London:     $(env TZ=Europe/London date +'%l:%M %p %A')";echo "Amsterdam:  $(env TZ=Europe/Amsterdam date +'%l:%M %p %A')";echo "Banglalore: $(env TZ=Asia/Kolkata date +'%l:%M %p %A')"