pyhail is a Python library providing hail retrieval algorithms for weather radar data. It supports both the Py-ART and pyodim radar interfaces and operates directly on native polar (PPI) data, with optional Cartesian gridding for MESH.

Four calibrations are available via the mesh_method parameter:

The blend formulation transitions smoothly from Witt (1998) at low SHI to Murillo & Homeyer (2021) at high SHI using a logistic weight, eliminating the discontinuous derivative of a hard piecewise switch. The crossover point is the analytical intercept of the two power laws (SHI ≈ 429 J m⁻¹ s⁻¹, MESH ≈ 52.6 mm).

When processing C-band radar data, MESH can apply a reflectivity correction for Mie scattering and attenuation effects using radar_band='C' and correct_cband_refl=True (Brook et al. 2023, arXiv:2306.12016).

Note: The HSDA Q confidence vector (Park et al. 2009) is not implemented; all pixels are assigned q = 1.

pip install pyhail

A full environment including Py-ART, pyodim, cartopy, and Jupyter is provided:

conda env create -f test_environment.yml
conda activate pyhail-test-env

git clone git@github.com:joshua-wx/pyhail.git
cd pyhail
pip install -e .

Core (installed automatically via pip):

• numpy
• scipy
• numba ≥ 0.59.1

Radar I/O (install separately, choose one or both):

• Py-ART — pip install arm-pyart
• pyodim — pip install pyodim

Notebooks only: matplotlib, cartopy, ipywidgets

The unit tests cover the pure mathematical functions: MESH calibration formulas, HSDA membership functions, the trapezoidal MF and aggregate scorer, and safe_log.

pytest must be installed in the active environment:

pip install pytest

If you are using the conda environment from test_environment.yml, activate it first:

conda activate pyhail-test-env
pip install pytest

From the repository root:

python -m pytest tests/ -v

To run a single test file:

python -m pytest tests/test_mesh_formulas.py -v

Working examples with bundled data are in notebooks/.

• Witt et al. (1998) doi:10.1175/1520-0434(1998)013<0286:AEHDAF>2.0.CO;2
• Murillo & Homeyer (2021) doi:10.1175/JAMC-D-20-0271.1
• Ortega et al. (2016) doi:10.1175/JAMC-D-15-0203.1
• Ryzhkov et al. (2013) doi:10.1175/JAMC-D-13-074.1
• Depue et al. (2007) doi:10.1175/JAM2529.1
• Wallace et al. (2019) doi:10.1175/WAF-D-18-0053.1
• Kalina et al. (2016) doi:10.1175/WAF-D-15-0037.1
• Brook et al. (2023) arXiv:2306.12016

Please use the GitHub issue tracker to report bugs or request features. Maintained by Joshua Soderholm (joshua.soderholm@bom.gov.au).