Model:

ECMWF: Global weather forecast model from the "European Centre for Medium-Range Weather Forecasts"

Updated:
4 times per day, from 00:00, 06:00, 12:00 and 18:00 UTC
Copyright:
This service is based on data and products of the European Centre for Medium-Range Weather Forecasts (ECMWF)
Source: https://www.ecmwf.int
Licence Statement:
This ECMWF data is published under a Creative Commons Attribution 4.0 International (CC BY 4.0).
Link: https://creativecommons.org/licenses/by/4.0/

The maps produced by WeatherOnline are subject to the Terms and Conditions.
Disclaimer:
ECMWF does not accept any liability whatsoever for any error or omission in the data, their availability, or for any loss or damage arising from their use.
Greenwich Mean Time:
12:00 UTC = 14:00 CEST
Resolution:
0.25° x 0.25°
Parameter:
Precipitation in mm (or litres per square metres)
Description:
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.
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).