Marshall MRMS Mosaic Python Toolkit#

Quick description#

The National Oceanic and Atmospheric Administration (NOAA) regularly produces national 3D radar reflectivity mosaics via its Multi-Radar/Multi-Sensor (MRMS) system. These mosaics are wonderful for storm and precipitation analysis and research, but they are distributed in odd formats that NOAA is ever changing. Sometimes you just want to read a file and make a plot! This is what MMM-Py is for. With it, you can read any version of the MRMS radar mosaics, past or present, and you can analyze, plot, subsection, and output custom mosaics of your own, which MMM-Py can ingest later. MMM-Py is free and open source. It is capable of producing publication-ready figures and analyses, but it also can do quicklook plots so you can check out the cool storm that just happened.



Code Repository#


Software Documentation#


User group or forum page#


License model#

NASA Open Source 3.0

Year of first release#


Main programming laguage(s)#


Supported platforms#

Linux. Mac

Type of software#


Further details#

For more info about the latest version of MRMS, see:

MMM-Py Installation#

MMM-Py works under Python 2.x on most Mac/Linux setups. Windows installation is currently untested.

Put in your PYTHONPATH

You’ll need the following Python packages. Most are easily obtained or already installed with common Python frameworks such as Anaconda ( numpy, matplotlib, scipy, netCDF4, os, Basemap, struct, time, calendar, gzip

Get MRMS-modified wgrib2 package from here

Install wgrib2 and note the path to it. Modify the BASE_PATH, TMPDIR, WGRIB2_PATH, and WGRIB2_NAME global variables in as necessary. TMPDIR is where intermediate netCDFs created by wgrib2 will go.

Without wgrib2 MMM-Py can still read legacy MRMS binaries and netCDFs.

Using MMM-Py#

To access everything: import mmmpy

To see MMM-Py in action, check out the IPython notebooks provided in this distribution.

The following conference presentation discusses MMM-Py (among other modules):

MMM-Py was developed at the NASA Marshall Space Flight Center by Timothy Lang (

See LICENSE file for NASA open source license information.


Lang, T. J., Python-based scientific analysis and visualization of precipitation systems at NASA Marshall Space Flight Center. 5th Symposium on Advances in Modeling and Analysis Using Python, American Meteorological Society, Phoenix, AZ. (available online at; 2. Lang, T. J., S. A. Cummer, D. Petersen, L. Flores-Rivera, W. A. Lyons, D. R. MacGorman, and W. Beasley (2015), Large charge moment change lightning in the El Reno tornadic storm system, J. Geophys. Res. Atmos., Accepted.