Model:

Ensemble forecast charts of several different numerical weather prediction (NWP) models

Ververst:
2 times per day, from 05:00 and 17:00 UTC
Greenwich Mean Time:
12:00 UTC = 13:00 MET
Resolutie:
Parameter:
Verticale beweging op 500 hPa in hPa/h
Beschrijving:
De verticale beweging van de lucht bepaald in hoofdlijnen het weer op een bepaalde plaats. Stijgende luchtbeweging (negatieve waardes in de kaart) veroorzaakt meestal bewolking en vaak ook neerslag, terwijl dalende luchtbeweging (positieve waardes in de kaart) voor oplossende bewolking en zonnig weer zorgt. Bij zeer sterke verticale luchtbeweging hoort in principe onweer en zwaar weer. Door de combinatie met vertical 925 kan met zien of ook in diepere lagen al forse stijgbeweging optreedt. Bij vermenigvuldiging van de waardes in (hPa/h) met ongeveer 0.3 krijgt men als resultaat de verticale wind in cm/s. De verticale beweging is de som van vorticiteits- en temperatuuradvectie. Deze twee kunnen afzonderlijk groot zijn en elkaar deels of geheel opheffen.
Spaghetti plots:
are a method of viewing data from an ensemble forecast.
A meteorological variable e.g. pressure, temperature is drawn on a chart for a number of slightly different model runs from an ensemble. The model can then be stepped forward in time and the results compared and be used to gauge the amount of uncertainty in the forecast.
If there is good agreement and the contours follow a recognisable pattern through the sequence then the confidence in the forecast can be high, conversely if the pattern is chaotic i.e resembling a plate of spaghetti then confidence will be low. Ensemble members will generally diverge over time and spaghetti plots are quick way to see when this happens.

Spaghetti plot. (2009, July 7). In Wikipedia, The Free Encyclopedia. Retrieved 20:22, February 9, 2010, from http://en.wikipedia.org/w/index.php?title=Spaghetti_plot&oldid=300824682
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).