Thornhill!
Overview:
When those summer storms or winter blizzards come rolling in, it can be handy to look at a weather radar to determine their direction and possible intensity. Not wanting to have another open tab on my web browser, I made the Weather Radar! as a permeant radar viewer for my desk!
Connected to Wifi, the Radar! downloads NWS radar images, overlays them on a map, and plays looping animations of the 1-hour precipitation layer. With OpenWeather data, the Radar! also shows current weather conditions and the forecast for the next few days.
A toggle switch and 5-way navigation switch allow switching between modes/pages, while a potentiometer acts as a zoom knob for the map.
Background
The NWS has a new radar webpage that uses HTML5, an interactive map, and Open Geospatial Consortium (OGC) compliant layers. These layers are especially handy because they can provide us with radar images for a particular area via a simple URL request (using Web Map Service WMS or Web Feature Service WFS protocols).
The NWS helpfully provides a page of the OGC compliant layers they offer, including alerts, warnings, and layers for the 200+ weather radar stations… (which I apparently missed when I started working on this!).
Methodology:
For a given latitude and longitude in the USA, the Radar!:
- Obtains the nearest radar station ID (using the Weather API service)
- Uses the radar station ID (e.g. KJAX) to obtain metadata and times for previous radar layers (e.g. XML GetCapabilities document for the 1 hour precipitation layer for the radar station in Jacksonville).
- Generates a tiled base map using the GeoTiler library (using a given zoom level, map size, and map centre).
- Uses all of this information to make a WMS request and download the last 5 - 10 radar images.
- For each time frame, combines the base map, radar image, and other layers and annotations using the Pillow imaging library.
- Displays the combined image for each time frame, to make a looping animation.
- Uses the latitude and longitude to get OpenWeather data for some extra forecasting jazz.
B) Radar image is added on top with slight transparency. Also a marker for our starting lat long position.
C) Now combined with labels, annotation, and weather data. A circle overlay is added to make it blend better with the analogue meter case.
Code:
The Weather Radar! is written in Python with Blinka support!
I'm slowly adding example code over on the Weather Radar! github page!
Hardware:
The Weather Radar! uses a Raspberry Pi Zero W with a 2.4" Adafruit PiTFT HAT. The Pi runs in headless mode, with the HAT as a SPI screen using Blinka and the RGB Display library.
An Adafruit PCF8591 gives the Pi ADC support to read the analog voltage from a potentiometer mounted on front, while a toggle switch and a 5 way navigation switch connect to the Pi's GPIO pins.
Case:
The case is from an old analogue meter I found discarded in my shed 5 years ago. While the battery and electronics inside had mostly crumbled away into toxic dust, the case and screws were still ok! After a thorough clean and a bit of patching with some wood filler, I gave the case a nice coat of sky blue paint (… because you know… weather).
Inside, the Pi and PiTFT HAT attach to the remnants of the meter gauge housing using a mount I designed and 3D printed. A cheap magnifying lens enlarges the screen a little and gives it a slight retro look (especially when viewed from an angle!).
References & Attribution:
- Radar images from the National Weather Service, weather data from OpenWeather.
- Maps by Stamen Toner under (CC-BY-SA), with invaluable handling by the GeoTiler python library.
- CircuitPython library handling by Blinka.
Craig Hissett
Initial State
Diego
rlsutton1
Very well done! Thank you for taking the time to write an engaging text.