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ESSEM COST Action 722
Short range forecasting methods of fog, visibility and low clouds

Meteorological forecasting at a very short notice (up to 12 hours) is called nowcasting. Numerous customers, particularly from transport companies, request nowcasting of fog, which is a limiting factor of visibility. Effective, useful nowcasting of visibility, fog and low clouds is constrained by the availability and quality of observational data, by the meteorological situation and by the quality of the forecast methods. Furthermore, the production and dissemination of various nowcasting products that are tailored to the needs of the individual customers require flexible and user-friendly application software.

The main objective of the Action was to develop advanced methods for very short-range forecasts of fog, visibility and low clouds, adapted to characteristic areas and to user requirements. The first objective was to develop pre-processed methods of the necessary input data. The Action also focused on the development of the appropriate forecast models and methods, as well as on the development of adaptable application software for the production of the forecasts.

The Action focused firstly on an inventory of the Existing forecast methods of fog, visibility and low clouds and on an investigation of the Requirements from the forecasters and from the customers mainly within European countries.

Based on the insight that precise input data are essential for all short range forecasts, an important topic was to provide an inventory of data sources available, along with assessments of accuracy and reliability. The Action studied the potential of satellite data (e.g. Meteosat Second Generation SEVIRI, Terra/Aqua MODIS and NOAA AVHRR) for initialising models, the combination of satellite and ground-based observations, analysed fog climatologies and assessed current measurement techniques. In addition, COST 722 Action developed new fog models, improved physical parameterisations in fog models and the performance of model intercomparisons of one-dimensional and three-dimensional fog models. Finally, innovative statistical methods for forecasting low visibilities were developed by use of Artificial Neural Networks, fuzzy logic techniques and decision trees. It was demonstrated that statistically tackling the problem of forecasting ceiling and visibility, can be effectively a relevant approach.

The final report of the project is available on the COST webpage of the Action ( and software packages are available on the website organised by the Action (

(Descriptions are provided by the Actions directly via e-COST.)

General Information*

Chair of the Action:

Dr Wilfried JACOBS (DE)

Vice Chair of the Action:


Science officer of the Action:


Administrative officer of the Action:



Action Fact Sheet

Download AFS as .RTF

Memorandum of Understanding

Download MoU as PDF

Final Report

Download Final Report as PDF


* content provided by e-COST.
Data is synchronised once per night.


Last updated: 02 May 2011 top of page