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What are “Computer models”?

We often talk about long range “computer models” and how they shift and change.  This might help better explain what they are.

Basically computers all around the world print out long range weather maps (charts) like the ones we see with the fronts on them – but minus the fronts, L’s and H’s.   These long range charts, along with data, allow forecasters to predict upcoming events.  The closer we get to the event the more confidence we usually have in them.

Here’s a blog you might find interesting from a meteorologist from a large private weather forecaster in the United States called

The Secrets of Computer Forecast Models

Hi, I’m Community Director & Meteorologist Jesse Ferrell. Based on questions from readers like you, I recently wrote a lengthy blog article about weather forecast model accuracy which you can read in its entirety here — below is an excerpt with the main points.

A meteorologist’s biggest job is deciding which model has the right idea for an upcoming storm. Weather forecast models are computer algorithms which predicts the weather, typically run on huge government computers, by the U.S. and other governments or institutions. These organizations typically produce their own maps and statistics from the models, and provide the raw data to commercial companies such as AccuWeather.



Some of the questions that readers had were…
– Why are the models so inaccurate?
– Are they getting better over time?
– Who watches their accuracy?
The answers are surprisingly simple, though most meteorologists don’t talk about them. The state of the computer forecast industry as of today is as such:
The models are inaccurate due to a number of factors, including computer power, data input, and software. The U.S. Government (NOAA) and educational institutions monitor and tweak the accuracy of models. The U.S. long-range model is less accurate than the European model, but there is a plan to fix it. For a more detailed explanation, read my blog.



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