With Earl approaching the coast of North Carolina, I am aware that a number of people are taking a look at the “HUR-NC” forecasts. Here, I will provide a little bit of information about this model.
HUR-NC is the Advanced Research version of the Weather Research and Forecasting model, known as WRF-ARW. This model does include a simple ocean model, to cool the waters as a storm moves over. The physics of the model are more or less out of the box.
The model has an outer nest at 27km grid size, and a vortex following nest of 9km and 3km grid size. The vortex is selected by reading the ATCF files from NHC, and finding the storm of greatest threat to North Carolina. As configured, HUR-NC can only have the high resolution nest on one storm. We cannot, for example, do both Earl and Fiona at 3km.
The model uses the GFS for initial and boundary conditions. The GFS is normally available about 4 hours after the synoptic time (e.g., the 1200UTC GFS data is available at 1600UTC) and then HUR-NC takes about 4 hours to complete its run. Forecasts are 132-hours in length, though they are 8 hours old when they become available.
There is a web-site dedicated to the output of these runs. That web site is:
From there, you can get track maps, but if you click on ‘Hurricane’ under “WRF Images and Loops”, on the far left, you can get many more diagnostic plots.