Model:

557WW: "557th Weather Wing Ensemble" The US Air Force’s 557th Weather Wing creates the Global Ensemble Prediction Suite (GEPS) twice per day by ingesting 63 global forecast model runs produced by three operational numerical modeling centers and creating tailored statistical ensemble forecasts. Products include probabilities for precipitation and snowfall, and means/standard deviations of temperature, wind, pressure, height, and relative humidity. 240 hours of one-degree gridded forecast output is produced at 6 hour intervals on the 00Z and 12Z cycle.

Ververst:

2 times per day, from 06:00 and 18:00 UTC

Greenwich Mean Time:

12:00 UTC = 13:00 MET

Resolutie:

1° x 1°

Parameter:

Relatieve Luchtvochtigheid op 925 hPa

Beschrijving:

Deze kaart laat de berekende relatieve luchtvochtigheid zien op 925 hPa. Globaal gezegd stijgt lucht op aan de voorkant van troggen en bij fronten. De opstijgende lucht koelt af. Daarbij neemt de relatieve luchtvochtigheid toe. Op een gegeven moment condenseert er vocht en ontstaat er wolkenvorming. Hoge vochtwaardes op 925 hPa - dat is op ca. 700 m boven zeeniveau - hangen meestal samen met stijgings- en neerslag-actieve gebieden.

NWP:

Numerical weather prediction uses current weather conditions as input into mathematical models of the atmosphere to predict the weather. Although the first efforts to accomplish this were done in the 1920s, it wasn't until the advent of the computer and computer simulation that it was feasible to do in real-time. Manipulating the huge datasets and performing the complex calculations necessary to do this on a resolution fine enough to make the results useful requires the use of some of the most powerful supercomputers in the world. A number of forecast models, both global and regional in scale, are run to help create forecasts for nations worldwide. Use of model ensemble forecasts helps to define the forecast uncertainty and extend weather forecasting farther into the future than would otherwise be possible.

Wikipedia, Numerical weather prediction, http://en.wikipedia.org/wiki/Numerical_weather_prediction(as of Feb. 9, 2010, 20:50 UTC).