grib2pf

This is a python script and C code which takes GRIB data (mainly MRMS) and outputs it to a placefile for usage with Supercell-Wx. This adds the ability for nation wide weather radar in Supercell-Wx.

Update Guide Windows

There are 2 ways to update this on Windows. The second way is will allways work but takes a bit more effort. The first ways is simpler

Simple Update

Unzip the new grib2pf folder from the zip overtop your preexisting folder, and select "Replace the files in the destination". This will save your settings.

Complete Update

1. Go into the grib2pf folder, then the _internal folder.
2. Copy settings.jsonc or settings to your Desktop, or somewhere outside of the grib2pf folder.
3. Delete the grib2pf folder.
4. Unzip the new grib2pf folder where you want it.
5. Move the settings.jsonc or settings file back into the _internal folder inside the grib2pf folder.

Setup Guide Windows

There are 2 main ways to run this in Windows: WSL or via an executable. For WSL follow the Linux instructions. These instructions are for the executable.

Windows Dependencies

You will need the latest Microsoft Visual C++ Runtime to run this program. If you have Supercell-Wx v4.5.0 running on your system, then you should already have them. Otherwise download them from https://aka.ms/vs/17/release/vc_redist.x64.exe .

Download The Executable

Download the executable form the latest release and extract it. You will want to extract it to a permanent location. This program does not install itself, so where you place it is where it will be installed.

Running the GUI

grib2pf-ui.exe or grib2pf-ui can be run by double clicking it. This will launch a settings UI. You can select a preset to start with by clicking Load Preset. From there you can modify the settings to your liking. Clicking Run will save your settings and run grib2pf. Once your settings are saved, you can simply run grib2pf directly, without the GUI.

Run It

For a basic run, you can simply double click on grib2pf.exe or grib2pf. This will put a basic settings file (settings.json) in the _internal folder. It should look like below, where {_internal folder} is replaced by the path to the _internal folder.

{
    "url": "https://mrms.ncep.noaa.gov/data/2D/MergedBaseReflectivity/MRMS_MergedBaseReflectivity.latest.grib2.gz",
    "imageFile": "{_internal folder}\\baseReflectivity.png",
    "placeFile": "{_internal folder}\\baseReflectivity.txt",
    "verbose": true,
    "refresh": 15,
    "regenerateTime": 60
}

This will generate a base reflectivity placefile. The "URL" for this placefile with simple be the path following placeFile (You may need to change \\ to \). This setup will update the placefile every minute. Updating the placefile is somewhat slow, and the MRMS data is only updated every two minutes, so this should be enough. In order to stop it use press CTRL-C in the window it launches.

Using Multiple Placefiles

One way to have multiple placefiles is to simply copy the grib2pf folder. Each folder will have its own settings files. Just make sure that the paths in settings.json do not overlap.

Another way to generate multiple placefiles by having multiple settings files. By default, grib2pf only uses the _internal/settings.json file, but this can be changed. Probably the easiest way is to create a shortcut to launch grib2pf with an argument. In the Create Shortcut dialog, simply enter the path to grib2pf.exe followed by a space, and then the path to your settings file. You may want to use quotes around the paths. Below is an example.

"C:\Users\user\Documents\grib2pf\grib2pf.exe" "C:\Users\user\Documents\grib2pf\settings2.json"

Double clicking on this shortcut will launch grib2pf using the given settings file.

Installing on Linux

To install on Linux you can simply download or clone the repository, then run the following command to install all dependencies.

git submodule update --init --recursive
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make
cd ..
pip install -r requirements.txt

You can then run grib2pf.py and grib2pf-ui.py as normal scripts.

This will only work if your distro does not manage your Python packages. Otherwise, you can use a Python virtual environment. To do so, do the following.

python3 -m venv venv
./venv/bin/pip -r requirements.txt

In order to run grib2pf.py, use

./venv/bin/python grib2pf.py

If you are using WSL, you will want to modify the path to output the placefile and image in settings.json to a folder accessible by Windows.

Adding To Supercell-Wx

Copy the path to the placefile, and use it as the URL for a placefile in Supercell-Wx. It is recommended to place your grib placefile layer(s) below the radar layer. The local radar will have a higher resolution, and have more plots. You could also only enable the grib placefile layer(s) on specific panes.

Contours

Contours are an optional feature which can be used to help see how data is changing over distance. It is similar in concept to isotherms. Each color table entry is given a contour. Only the pixels that are determined to be contour are rendered. They have their initial value, so the color table can define the color of given contours. Below is an example color table that can be used with Kelvin based temperature data. It covers -30 to 40 degrees Celsius, with a contour every 10 degrees.

offset: -273

Color: -30   0   0   0
Color: -20   0   0 255
Color: -10   0 255 255
Color:   0   0 255   0
Color:  10 255 255   0
Color:  20 255   0   0
Color:  30 255   0 255
Color:  40 255 255 255

Arguments

When run without an argument, grib2pf will run using the settings file in the install directory (grib2pf on Linux, and grib2pf\_internal on Windows). When run with one argument, grib2pf will use that argument as the path to a settings file. Otherwise, grib2pf can be run without a settings file, using arguments instead. The arguments documentation can be seen by running grib2pf with --help. The arguments align with the settings described below.

Other Radar Viewers

If another radar viewer uses a Mercator projection and has placefile support, this project should work, although I give no guaranties.

Overview of how grib2pf Works

The grib2 files provide a grid (in a variable coordinate space) of data. Each grid point has a value, latitude, and longitude. grib2pf converts the latitudes and longitudes to x,y coordinates on a Mercator projection. In order to maximize the pixel density of the output image, these x,y coordinates are normalized such that 0,0 is the top left, and imageWidth - 1,imageHeight - 1 is the bottom right of the grib data (image coordinates). This is simply a linear transformation of normal Mercator projections, which is undone when the placefile is rendered because of the latitude and longitude coordinates saved in the placefile. The pixels values are determined in several modes depending on renderMode. Average_Data averages the data under the pixel. Nearest_Data and Nearest_Fast_Data find the nearest data point to the center of the pixel (Nearest_Data should be used if the resolution of the image is higher than the resolution of the data. AKA if you are seeing holes in the data). Max_Data uses the largest value under the pixel. Min_Data uses the smallest value under the pixel.