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EZTip No. 34 - Is MOS used in the EZForecast?

It's a common question from EZWxBrief subscribers. What forecast is used to produce the guidance shown for the station markers like the one below? It is true that many of the heavyweight and lightweight apps utilize model output statistics (MOS) as part of their hourly forecast. While MOS is a useful tool, it can be problematic at times since it essentially relies on a single forecast model for many of the forecasts to include wind, ceiling and visibility. If that model has a good initialization and has a good grasp of the weather, then the MOS will usually provide a good solution. But what if the model is out to lunch?

That's where EZWxBrief really excels. It does not rely on any single forecast model or forecast guidance for the surface-based "EZForecast" you see on the EZMap, EZRoute Profile or the Meteogram. It uses a unique mix of models that are properly blended together where MOS is just one of a dozen or more models incorporated as part of that blend. Depending on the forecast element (e.g., ceiling height), MOS may be weighted higher or lower and will usually result in a forecast that is "on average" better than using any single model. By the way, in the current version, the EZForecast does not employ the terminal aerodrome forecasts (TAFs). We are looking at adding that to the mix of forecast guidance used for a future release.

If you want to learn more about weather and how to interpret the Skew-T log (p) diagram, you can order your copy of The Skew-T log (p) and Me: A Primer for Pilots that is available in both softcover and eBook format.

Most pilots are weatherwise, but some are otherwise™

Dr. Scott Dennstaedt

Weather Systems Engineer

Founder, EZWxBrief™

CFI & former NWS meteorologist

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