Thanks to Ron Gleason:

http://cliffmass.blogspot.com/2016/07/the-national-weather-service-moves-to.html

This week the National Weather Service (NWS) made an important
announcement: its decision for the dynamical core of its new global model, the
Geophysical Fluid Dynamics Lab (GFDL) FV-3. At the same time, they turned down
the global model developed by the National Center for Atmospheric Research (NCAR)
called MPAS (NCAR is the combined entity of the academic research community of
the U.S., representing over 100 college and universities).

The current NWS global model (GFS) needs to be replaced

As I have discussed in several blogs, the current NWS Global Forecast System (GFS)
is out-of-date in many ways. It was designed for low-resolution weather
prediction and does not scale well on modern supercomputers (which can have tens
or hundreds of thousands of processors). GFS physics (the descriptions of
physical processes such as convection and clouds/precipitation) are ancient,
representation the state of the science 20-30 years ago. The range and amount of
data assimilated into GFS forecasts is less than leading centers (such as the
European Center) and the quality control system lags. We can do much better.

72-h cumulative precipitation from the GFS forecast initialized at 1800 UTC 30
July 2016. The "popcorn" look to the precipitation in mountains is not realistic
and reflects inferior, 20-year old precipitation physics in the model.

The NWS GFS global model is now third or fourth globally, a particular
embarrassment since the range and quality of US. Weather research is by far the
greatest in the world. The general U.S. population finally understood the
situation when important forecasts by the GFS (e.g., Hurricane Sandy) were
clearly inferior to those of the European Center and UKMET office. So does NWS/
NOAA management and Congress, which provided funds for both a new operational
computer and model replacement.