Weather Computer Models

You’ve heard us say the words “Computer models” often in our weathercasts. What are computer models?Computer models give us an idea of what the weather could be. Computer models are updated by super computers with a lot of processing power in different locations across the world.  Now some could say they are not always 100% correct. When learning how to forecast in meteorology classes you learn that models should only be used as guidance. They tend to be wrong on occasion but most important you have to learn the different biases. Some biases include topography, your location in relation to water bodies, mountains, and anything else that may affect the weather.

There are numerous computer models out there. Most of them are free and open to the public (We’ll give you a link later).  There are even computer models that we use here in U.S. that are updated overseas. We at KSAT have access to many models. Most are on the Internet while  some are provided by our weather vendors. They give us an idea of what the weather could be. Typically models are pretty good out to about 3 days but after 3 days the percentage of error increases.

What makes models so different? Each model has it’s own uniqueness and its own name/acronym. For example the GFS(Global Forecast System) is a long range model that goes out about 10 days. One short range model is called the RUC (Rapid Update Cycle) that updates hourly. This is mainly used in winter or severe weather situations.

One thing forecasters have to keep in mind is that weather is 3D. You always have to look at the surface, all the way up to about 35,000 ft in the air when you forecast.  You can’t just focus on one area of the model.

Where to look? One place to find good models is the National Center for Environmental Prediction website provided by NOAA. Like I said, models have different update times.  Some update two times a day, some 4 times a day, and hourly like the RUC.

If you want to give a stab at it, here are some hints:

00 UTC = 7PM (The previous day; Central Time Zone)

06 UTC = 1AM (Central Time Zone)

12 UTC = 7AM(Central Time Zone)

18 UTC = 1PM(Central Time Zone)

I like looking at the medium runs.

The surface option on GFS: 10m Wind 06hr precipitation. (This is good to look at)

850mb = ~5000 feet in the air

700mb = ~10,000 feet in the air

500mb ~18,000 feet in the air

300mb ~30,000 feet in the air

So with the chances of rain going up this week this would be a great time to do a little forecasting with us. We even have a Twitter WebPoll asking how much rain you think we might see this week. Vote at

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