There are "Forecasts" and then there are Forecasts
There are three key players involved in the weather forecast process:
- the data collectors,
- the weather modelers, and
- the weather agencies.
The end users of this process are the clients themselves. For Everest, clients are the climbing teams needing weather forecasts to inform their approach to the summit.
- The Data Collectors - The role they play is to gather data on the current weather condition (temperature, wind speed and direction, barometric pressure, humidity, and precipitation) from a variety of sources such as weather balloons at different altitudes, satellites in space, ships at sea, airplanes during take-off and landings, weather stations around the globe, etc. This data is continuously gathered and fed to the organizations that then use the data in their mathematical weather models.
- The Weather Modelers - This includes organizations such as the European Centre for Medium-Range Weather Forecasts (ECMWF), India's National Center for Medium Range Weather Forecasting (NCMRWF), and the Navy Operational Global Atmospheric Prediction System (NOGAPS). These organizations build weather models that use the data provided from the sources mentioned above. Via super computers such as a Cray SV1 with 24 processors, the data is processed through a labyrinth of complex mathematical algorithms. The algorithms, as well as a host of assumptions the modelers make, tend to vary considerably from one modeling organization to another. To continuously improve the models, the projected weather is compared to the actual weather experienced and where inaccuracies occur, they are investigated and the models are then further refined as appropriate. Typically, the models will be "ran" twice a day — the output being a series of raw data, weather maps, and preliminary forecasts that various agencies around the world will then use.
- The Weather Agencies - This includes companies like Michael's West Coast Weather LLC. These groups reference the output of the modeling organizations to develop their forecasts. In some cases, agencies will develop their forecast via an automated process. For example, if you get your forecast from www.weather.com, you're seeing a forecast generated by computers — no human intervention has occurred. In many cases, this type of forecast as provided by groups like Accuweather and the Weather Channel is fine. It's fast and free and generally pretty good. In contrast, considerable human input takes place when forecasting weather for a place like Everest. Experience and judgment is involved, adding some art to what otherwise would be a pure science. Sometimes the models are off and human intervention based on experience can catch such occurrences. Other forecasting groups include SMHI and various other government agencies. Also note that whereas forecasters like Accuweather provide automated forecasts, they also provide more customized, non-automated forecasts for clients such as large energy companies.