Meteorology uses pressure as the vertical coordinate and not height. This works out better for thermodynamic computations that are done on a regular basis. Pressure decreases in the atmosphere exponentially as height increases reaching zero pressure in space. The standard unit of pressure is millibars (mb or hectopascals-hPa) of which sea level is around 1013 mb. Standard pressure levels and approximate heights:
The the primary difference between the models is their resolution or grid boxes. The smaller the grid box, the higher the resolution so little nuances in the atmosphere are more easily identified. Below are some of the models used by the National Weather Service.
Model Data Servers
NAM Forecast Model
This table contains contour plots of data from
the NAM forecast model. This model gives forecast information
out to 84 hours and are updated once every 6 hours at roughly
02:00 PST and 08:00 PST.
NAM MOS Numerical Guidance:
GFS (Global Forecast System) Forecast Model
This is a global model run by NCEP whereas the NAM is a regional model. As a result,
the grids from this model are somewhat coarser than the grids from those models and lack some
products. This model replaced the AVN and MRF models and gives forecast information out to
384 hours, and are updated once every 6 hours by roughly 04:00 and 10:00 PST.
GFS Short Range Numerical Guidance:
GFS Medium Range Numerical Guidance:
US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
San Joaquin Valley Weather Forecast Office
900 Foggy Bottom Road
Hanford, CA 93230-5236
Tel: (559) 584-3752
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