WRF Hi-Res 48-Hour Forecasts for Wildfires and Other Emergency Applications in

California and Nevada  




                 Read Important Disclaimer Below Before Using Forecasts
                     IMPORTANT DISCLAIMER
The free WRF forecasts are produced by AMI Environmental (AMI) on an experimental basis, and are provided for evaluation and demonstration purposes only.The user assumes the entire risk related to its use of these forecasts. AMI is providing these forecasts "as is," and AMI disclaims any and all warranties, whether expressed or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will AMI be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages resulting from any use or misuse of these forecasts.


  • Read Important Disclaimer,
  • Look up the above AQI (Air Quality Index) daily maps and the AQIs forecasted for the nearest monitor in the California AQI table or the Nevada AQI table. Predicted AQI above 150 indicate unhealthy levels,
  • Examine the plots of hourly concentrations of ozone, particulate matter (PM2.5 and PM10) at California Monitors or Nevada Monitors to determine the pollutant levels,
  • Consult Surface weather mapsOzone maps and PM2.5 maps  to determine local wind, temperature and pollutant levels,
  • Examine Precipitation maps to see if any rain is coming,
  • Find out active fires from USFS/NASA websites,
  • Follow the orders and recommendations of local authorities.



Surface Winds, T
850 mb
700 mb
500 mb
300 mb
D01 (12km) surface precip 850 700 500 300
D02 (So. CA 4km) surface precip 850 700 500 300
D03 (No. CA 4km) surface precip 850 700 500 300


  • All times on the maps are UTC (Coordinated Universal Time) . To convert to Pacific Standard Time (PST), subtract 8 hours (PST= UTC - 8).
  • Wind speed and direction are represented by wind barbs. The direction the wind is blowing from is represented by a staff or wind direction line. Wind speed (in knots) is denoted by the barbs at the end of the wind direction line (short lines 5 knots; long lines 10 knots; flag 50 knots). Calm winds are indicated  by 0s.
  • Surface wind speed in knots (1 kt = 1.15 mph = 1.9 km/hr). 



In recent years, wildfires have caused substantial losses in both human life and property throughout the states of California and Nevada. In 2020, more than 4 million acres of land burned in California, with more than 10,500 structures destroyed and 31 people killed. These fires are expected to increase in both number and intensity due to climate change. Planning and protection against wildfires and other similar emergencies require both accurate weather forecasts and air quality impacts. Ozone and particles (PM2.5 and PM10) caused by fires can have serious health effects that are evaluated with the use of Air Quality Index (AQI) as defined by the US EPA. Instead of calculating AQI for a few monitoring stations, our forecasts are based on the AQIs computed at several thousands grid points as shown below. 

In this project, AMI Environmental utilizes the mesoscale model WRF (Weather Research and Forecast)  which is the most widely used and updated model available today. It has been developed by U.S. National Center of Atmospheric Research (NCAR) with contributions from weather agencies and universities, both in the US and around the world.  The WRF model is widely used in mesoscale meteorological modeling, including real-time forecasting,  and air quality studies by government agencies and well-known universities, both in the U.S. (e.g., EPA, National Weather Service and NASA) and abroad (e.g., Asia and Europe). Since 2000, AMI Environmental has applied the WRF model and its predecessor MM5 model in weather forecasts, air quality studies and wind energy applications, e.g. daily 72-hour weather forecasts for Southeast Asia.

As shown below, the WRF domains cover most of California and Nevada. Three nested modeling domains are used:

Daily four WRF weather forecasts, valid for 48 hours, are available for 00 UTC (16 PST), 06 UTC (22 PST), 12 UTC (04 PST) and 18 UTC (10 PST).  Initial and boundary conditions are derived from the NCEP NAM CONUS forecasts. The forecasts are updated with the latest weather information and reports from satellites, radars, weather stations, airports and ships in the region. These weather forecasts were generated for all three modeling domains.

Further, the WRF-Chem model with updated photochemistry and emissions is used to predict pollutant impacts on ozone, PM2.5 and PM10 air quality. Photochemical modeling requires extensive computing resources.These air quality forecasts are only produced daily for 06 UTC (22 PST) and 12 UTC (04 PST) for  the 12-km domain D01. In emergency situations such as urban/forest fires and pollution episodes, forecasts are also generated for the 4-km nested domains D02 and D03 if necessary.  More details are available in a recent AMI publication (Tran, 2021).   

We hope that these WRF forecasts will be useful in emergency planning, such as forest/urban fires, storms and air pollution episodes, so that potential losses of both life and property can be minimized.

 CONTACT: Khanh Tran, AMI Environmental, Henderson, Nevada


Last modified: March 2021