What is NAM weather model and how it works

What is NAM weather model and how it works

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The NAM weather model is one of two major regional weather forecast models for North America, on a par with the HRRR. In other words, if right now you're looking at the weather forecast for the US, Canada, or Mexico, it's probably from one of these two models.

In this post, you will learn about NAM model, its working principle and the main features, and where to find the weather forecast by this model.

What is NAM weather model?

The NAM (North American Mesoscale Forecast System) is a regional model for North America: Unites States, Canada, and Mexico, produced by the American weather service called the National Centers for Environmental Prediction (NCEP).

It has a much better resolution than global models such as the GFS and takes small-scale weather phenomena into account, which makes it the most effective model in that region.

The official website of the model is Ncdc.noaa.gov.

What are the main features of NAM weather forecast model and how it works?

The NAM model has a resolution of 12 km. The resolution is the distance between two points of the weather model grid. Bigger resolutions of 50 to 10 km in size are usually deployed in relatively flat terrains, while mountain ranges require the nodes to be a lot closer to each other, usually 5, 2, or 1 km.

The forecast depth of NAM weather model is 2.5 days or 61 hours. The depth of the weather forecast is the number of hours or days for which the forecast is made. As a rule, the lower the depth, the more accurate the forecast.

The NAM forecast step is 1 hour. The forecast step is for how long you can see a forecast in the application or on a website. There are two main step types: 1 h and 3 h.

The NAM updates frequency is 2 times a day. The update frequency of the forecast is the regular time interval after which new forecast data is received from the supercomputers. There are models like HRRR with 24 times a day updates, but in general, the frequency of the updates of weather models is 1, 2, or rather 4 times a day.

Let's sum up the main features of NAM model:

  • Resolution: 12 km
  • Forecast depth: 2.5 days (61 hours)
  • Step: 1 hour
  • Updates frequency: 2 times a day

Where to get the weather forecast from the NAM model in Windy.app?

The NAM weather model is also the main model in Windy.app among 10+ other models. In the app, the model has the same 12 km resolution. To get a weather forecast:

1. Open your favorite or the nearest spot to your current location in the United States, Canada, or Mexico in the app from the Home screen or Wind and precipitation map. For example, water sporst spot Los Berriles, Baha California, in Mexico. To see the nearest spots, allow the app to see your location in Settings.

 

 

2. Choose NAM weather model in the slider under the Wind rose:

 

3. Read the weather forecast from the NAM model for your particular sport. In Windy.app you can get the following weather parameters from the NAM choosing different Weather Profiles for sports like surfing, biking, skiing, and others:

  • Wind direction (both cardinal and degrees)
  • Wind speed
  • Wind gusts
  • Air temperature
  • Atmospheric pressure at sea level
  • Clouds
  • Precipitation
  • Snow depth

(On the screen, there are also additional weather parameters like swell, for example, which comes to form the different models.)

 

In addition, you can have the general weather conditions: sunny, rainy, cloudy, etc. from the NAM weather model. They are represented by an icon:

 

Also, you can get three charts:

  • Atmospheric pressure at sea level chart
  • Rain and snow chart
  • Clouds and precipitation chart

 

4. Choose or delete one of these weather parameters using the Customization feature. That how you will make your own custom weather profile in Windy.app:

 

 

5. Compare weather data from NAM model to other models in Windy.app using special Pro feature Compare mode.

 

6. Compare NAM weather forecast accuracy with other weather models thanks to special Windy.app feature based on data directly from weather stations. The weather stations are always located on the same spot's screen:

 

7. Return to Wind and precipitation map to see the bigger wind picture in the region from the NAM model.

 

Read about other weather models like ECMWF, ECMWF-ENS (Ensembles), GFS, ICON, or a guide to all weather forecast models used in Windy.app and the general guide to weather forecast models all around the world.

 

Text: Windy.app team. Cover photo: Oc-gonzalez / Unsplash.

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