National Weather Service United States Department of Commerce

Scattered Severe Thunderstorms Across the Northern Plains; Fire Weather Concerns in the Western U.S.

Scattered severe thunderstorms are forecast across central and eastern North Dakota, as well as far northwest Minnesota Saturday (Slight Risk level 2 of 5). Damaging wind gusts are the primary threat. Elevated to critical fire weather conditions will persist through the weekend across the Western U.S. Isolated dry thunderstorms could lead to new fire starts over portions of the northern Rockies. Read More >

Forecast Models


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: 
 

Pressure Approximate Height Approximate Temp
Sea level 0 m 0 ft 15oC 59oF
1000 mb 100 m 300 ft 15oC 59oF
850 mb 1,500 m 5,000 ft 5oC 41oF
700 mb 3,000 m 10,000 ft -5oC 23oF
500 mb 5,000 m 18,000 ft -20oC -4oF
300 mb 9,000 m 30,000 ft -45oC -49oF
200 mb 12,000 m 40,000 ft -55oC -67oF
100 mb 16,000 m 53,000 ft -56oC -69oF


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 North America Forecasts
NAM North Pacific Forecasts


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 North America Forecasts
GFS North Pacific Forecasts


GFS Short Range Numerical Guidance:

GFS Medium Range Numerical Guidance: