Pacific Northwest MM5-NAM/MM5-ETA Quick-Look Weather Forecasts: Information

For a description of our real-time high-resolution WRF forecasts click here

General Information: The Department of Atmospheric Sciences at the University of Washington ran the Penn State/NCAR mesoscale model version 3.6.3 (MM5 v3.6.3) twice a day until March 15, 2023. The MM5-NAM was used to produce a rapidly available medium resolution meteorological forecast for the Pacific Northwest using a frozen version of the model code.

Model Configuration: The MM5 numerical forecasts featured an outer grid of 36 km horizontal resolution that covered much of western North America and the northeastern Pacific and a nested grid of 12 km resolution that covered Washington, Oregon, and Idaho. The regions covered by each domain, showing topography and land use categories are shown in these plots:

36-km terrain 36-km land use

12 km terrain 12 km land use

A land use category color key is included in the links above, you may view it alone here.

A detailed description of the domain boundaries as well as the actual terrain.namelist are given here. Detailed land use information for each domain was derived from the 1-km USGS digital database, with some subjective modification using other data sources.

The model utilized 38 vertical full-sigma levels see below, and was run in non-hydrostatic mode in order to limit pressure gradient force errors over the complex terrain. An upper-radiative boundary condition was used to allow gravity waves to radiate through the model top without being reflected. The following table describes the phyics options we used:

Phyics Options:

Physics Comments

Dudhia Cloud-Radiation

Simple Ice Microphysics

Dudhia Simple Ice Microphysics

Kain-Fritsch Cumulus
MRF PBL Also known as the Hong-Pan PBL (Hong and Pan 1996).

5-layer Soil Model Dudhia scheme predicting temperature at approximately 1, 2, 4, 8, and 16 layers with a fixed substrate below.

Here is a sample mmlif file that was used to run the model: 36/12 km mmlif.
For more information on any of these options, see the MM5 chapter of the MM5 tutorial notes.

Physics	Comments
Dudhia Cloud-Radiation
Simple Ice Microphysics
Dudhia Simple Ice Microphysics
Kain-Fritsch Cumulus
MRF PBL	Also known as the Hong-Pan PBL (Hong and Pan 1996).
5-layer Soil Model	Dudhia scheme predicting temperature at approximately 1, 2, 4, 8, and 16 layers with a fixed substrate below.

Initializations: Initial and lateral boundary conditions for the MM5 were generated by interpolation of the National Centers for Environmental Prediction (NCEP) "NAM" model analysis and forecast fields. The exceptions were: 1) SST was from the 1/4 degree OTIS grids, 2) surface temperature was from the NAM 221 grids (40-km grid spacing), and 3) subsurface soil temperature and moisture were also from NAM 221 grids.

Forecast: Forecasts were computed as follows:

MM5-NAM: 24-processor OpenMPI HP Xeon Beowolf cluster running Debian Linux.

The model produced output for an 84 hour forecast period over the 36 and 12 km domains.

Future Improvements: None planned. Frozen code.

Full Vertical Sigma Levels

Sigma: 1.00, 0.995*, 0.99, 0.985*, 0.98, 0.97, 0.96, 0.95*, 0.94, 0.93*, 0.92, 0.91*, 0.90, 0.88, 0.86, 0.83, 0.80, 0.77, 0.74, 0.71, 0.68, 0.64, 0.60, 0.56, 0.52, 0.48, 0.44, 0.40, 0.36, 0.32, 0.28, 0.24, 0.20, 0.16, 0.12, 0.08, 0.04, 0. * = added 7/9/2001 Half-Sigma Levels

K-index	Sigma	K-index	Sigma	K-index	Sigma
1	0.02	2	0.06	3	0.10
4	0.14	5	0.18	6	0.22
7	0.26	8	0.30	9	0.34
10	0.38	11	0.42	12	0.46
13	0.50	14	0.54	15	0.58
16	0.62	17	0.66	18	0.695
19	0.725	20	0.755	21	0.785
22	0.815	23	0.845	24	0.87
25	0.89	26	0.905	27	0.915
28	0.925	29	0.935	30	0.945
31	0.955	32	0.965	33	0.975
34	0.9825	35	0.9875	36	0.9925
37	0.9975

Past Domain Configurations: This table provides all the necessary information about previous domain configurations.

Domain Name	Code Version	First Forecast	Last Forecast	36 km Domain			12 km Domain			4 km Domain			Terrain Setup File	Full TER.PLT NCGM File
Domain Name	Code Version	First Forecast	Last Forecast	Terrain	Land use	Lat, Lon, Elev and Domain Extents	Terrain	Land use	Lat, Lon, Elev and Domain Extents	Terrain	Land use	Lat, Lon, Elev and Domain Extents	Terrain Setup File	Full TER.PLT NCGM File
aug02	3-6-4	2002090912	2023031500	terrain	land use	text file	terrain	land use	text file	terrain	land use	text file	terrain.deck	TER.PLT

Questions and Comments: We're always interested in feedback. Please direct any questions and comments you have to Mark Albright (marka@atmos.washington.edu) or Cliff Mass (cliff@atmos.washington.edu).