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Interpreting Data

How do I read the computer models?

The website provides a comprehensive selection of computer forecast models. These models are run on supercomputers using complex sets of equations and massive amounts of data. Most models have both a 00Z (10am EST) and a 12Z (10pm EST) run.

The first thing to do is decide on which model you are going to look at. MesoLAPS is run out to 2 days over a limited domain, encompassing Australia and surrounding areas. It is high-resolution and is good at picking up small scale rainfall events, and taking into account topography and coastlines. Often it will miss ?coastal showers?.

LAPS is run out to 3 days over the same domain as MesoLAPS. It is a lower resolution model than MesoLAPS so will not resolve topography or coastlines as well. The result of this is a ?smoothing? of rain areas, possibly affecting greater areas than would actually be the case.

GASP is run out to 8 days over a global domain. It is run at a lower resolution than LAPS and, as such, is the least accurate of the three BOM models at forecasting rainfall.

GFS is run out to 8 days over a global domain, and is generally far more accurate than GASP. This is the best model for 3-7 day forecasting in the Australian region. However, it is relatively low-resolution, so topography and coastlines will not be resolved as well as MesoLAPS.

Extended GFS is run out to 14 days over a global domain. This model should be treated with caution and generally only used to provide a rough guide as to trends. It will often vary wildly from run to run due to its long lead-time.

It is worth noting that all computer models are simply mathematical simulations of what the atmosphere is expected to do based on a set of initial conditions. They are not forecasts, and they should always be interpreted with caution.

The Synoptic Maps are prepared by meteorologists who use their skills and experience to interpret all the available computer models. These are often a better alternative to get an idea of what the weather will do in your area for the next week.

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