Arpège(Action de Recherche Petite Echelle Grande Echelle) from Meteo France
4 times per day, from 08:00, 14:00, 20:00, and 00:00 UTC
Greenwich Mean Time:
12:00 UTC = 14:00 CEST
0.04° x 0.04°
Precipitation in mm (or litres per square metres)
The precipitation map - updated every 6 hours - shows the modeled precipitation in mm.
The precipitation areas are encircled
by isohyets - lines with equal amounts of precipitation. However, modeling precipitation is
still not very reliable. If you compare the modeled results with observed values you will
realize that the model is nothing better than a first order approach. Yet this chart is of some
use for forecasters.
Note: Based on international convention meteorologists use the metric system. 100 mm of
precipitation is equivalent to roughly 4 inches.
The Arome forecasting system is a blend of the best components from the Méso-NH model, the Aladin model, and the IFS/Arpège data assimilation software. Its focus is on the numerical prediction of intense convective systems over mainland France by 2008. Other important weather phenomena will also begin to be reliably forecast, thanks to a high (kilometric) spatial resolution and the use of regional observing systems. The Arome software is designed to be accessible to a wide research community.
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).