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New NWP model: Model for Prediction Across Scales (MPAS)

Jeff Duda

site owner, PhD
Staff member
Site owner
The folks out at NCAR have been busy cranking out a next-generation numerical weather prediction model that may be a part of the next generation of forecasts used around the world. It's called MPAS (see title) and features a variable mesh grid, meaning the grid spacing can vary across the domain. It's run over a global domain, eliminating the need for lateral boundary condition forcing, which tends to overwhelm the forecast in limited-area models like the NAM, RAP, and HRRR after a certain point in the forecast. Because of the variable grid size, issues such as reflection of energy during changes in scale are minimized or eliminated, thus removing known nested NWP model artifacts that plague current limited area models. It also means you can run a global convection-allowing model! Today's computer technology probably can't support running a model like the WRF in such a configuration given the number of grid points required.

MPAS is not currently run operationally - only for various experiments. And not all experimental output is pushed to the website. However, a good starting place for graphics is here: http://www2.mmm.ucar.edu/projects/mpas/Projects/MPAS_CONV_2015/

For the 2015 Hazardous Weather Testbed Spring Experiment, I believe they are running MPAS in a 50/3 km configuration, meaning the CONUS is covered in a 3-km grid that expands to 50 km as you move away and towards the rest of the world. Graphical output for that configuration can be found at this link:

I think they will only be running that configuration for a few more weeks. I would be surprised if new forecasts were still being made after the second week of June. But at least until then, enjoy!
Yep, it's only being run during the Spring Experiment!

I'm one of the folks working with the MPAS output this Spring and the rest of the Summer, evaluating it's performance and verification.

I'll be making updated plots/animations throughout the rest of the experiment that can be found here if anyone is interested:

500hPa: http://arctic.som.ou.edu/mpas-500hPa.gif
Surface: http://arctic.som.ou.edu/mpas-sfc.gif
Reflectivity: http://arctic.som.ou.edu/mpas-refl.gif