NEXRAD-quickplot 0.6.3

easily download and plot NEXRAD weather radar reflectivity data

Nexrad Quick-plot

Easy Python download and plot NEXRAD N0Q compositive reflectivity. Uses RGB high resolution PNG images of North America.

Tested with pytest, flake8 and mypy type checking.

Install

python -m pip install -e .

Usage

RGB data scaling: NEXRAD N0Q base reflectivity maps.

• Black: No Data
• -32 dBZ .. 90 dBZ
• 0.5 dBZ increment

Download NEXRAD data

Get NEXRAD reflectivity data with parallel download:

python download-nexrad.py start stop outdir

example: download from 2018-01-01 to 2018-01-02 to ~/data/nexrad:

python download-nexrad.py 2018-01-01T00 2018-01-03T00 ~/data/nexrad

Plot NEXRAD reflectivity data

(georegistered via Cartopy)

Plot all data in directory:

python plot-nexrad.py ~/data/nexrad/

Plot a specific file (subplots if multiple files specified):

python plot-nexrad.py ~/data/nexrad/2018-01-01T12:35:00.png

Plot via file glob match:

python plot-nexrad.py ~/data/nexrad/ -pat 2018-01-01T12*.png

Keogram (specify lat or lon and value):

python plot-nexrad.py ~/data/2017-08-21/nexrad/ -keo lat 40 

Coordinates

EPSG:4326 coordinates (WGS84) are in .wld files, which are generally the same for wide time spans of data. The .wld format is like:

0.005 (size of pixel in x direction)
0.0 (rotation of row) (Typically zero)
0.0 (rotation of column) (Typically zero)
-0.005 (size of pixel in y direction)
-126.0 (x coordinate of centre of upper left pixel in map units--here it's WGS84 longitude)
50.0 (y coordinate of centre of upper left pixel in map units--here it's WGS84 latitude)

Notes

Mass image downscaling

For initial analysis, the original Nexrad image size of 12200 x 5400 pixels may be too high to complete in a reasonable time. I choose to downsize by a factor of 10, which takes a long time, but is a one-time process.

mkdir orig
cp *.png orig

nice mogrify -scale 10% "*.png"

If you have trouble with this being very slow, try:

MAGICK_TEMPORARY_PATH=/run/shm nice mogrify -scale 10% "*.png"