Report of the First Meeting of the Forecasters Working Group (WG-FC)

Innsbruck, 22 May 1996

After a general introduction to MAP by Peter Binder and Tiziana Paccagnella, Andrea Buzzi and Reinhold Steinacker presented a summary of the answers to a questionnaire distributed in March among the bench forecasters of the Alpine countries. The aim of this questionnaire was to identify the main problems which the forecasters meet while predicting heavy precipitation, thunderstorms, foehn and other orographic winds. A summary of the conclusions from this questionnaire will be published in the forthcoming issue of the MAP Newsletter.

A large part of the meeting was dedicated to the presentation and discussion of some of the so-called MAP episodes and other selected cases, in order to generally introduce the participants to the main objectives of the programme. The following cases were presented:

• Heavy precipitation case in Piedmont (Italy) on the 4-5 November 1994 (A. Selvini, P. Frontero): This case was well predicted by the models, the alert was given in time but there were some problems with the reaction to the alert.
• Heavy precipitation case in Vaison-la-Romaine (France) on the 21-22 September 1993 (J. Ruffié): This episode was underestimated by the models but the forecasters predicted larger amounts of precipitation and the alert was given on time.
• Five types of Foehn in the Innsbruck area (H. Pümpel): In this case most of the remarks were Centreed on the more general problem of Foehn prediction with numerical models and on the definition of the term Foehn. The resolution of the numerical models used at present does not allow a realistic representation of the Alpine valleys, consequently also the prediction of Foehn events in these valleys is of bad quality.
• Fast moving cold fronts north of the Alps (with emphasis on the case of 7-8 September 1995) (M. Kurz): Such cases occur 5 to 10 times a year. In the case of the 7-8 of September, at the time when the front was moving into Switzerland, its position at the ground was found to be several tenths of kilometres ahead of the corresponding precipitation area. In such cases radar measurements cannot be used to monitor the movement of the front.

At the end of the meeting the role of the WG-FC within MAP and goals of the future meetings were discussed. Unfortunately the time available for this discussion was rather short, therefore only a couple of initial agreements on the work to be done before the next meeting were reached but no long-term plan of the activities of the WG-FC was defined. The next meeting will probably take place at the beginning of 1997, its location has still to be defined.

The main role of the WG-FC is the support and real-time advising of the research teams for decision making during the Special Observing Period (SOP). During these weeks the forecasters of the WG-FC will be working, two at a time, at the operation centre to advise the researchers in the planning of the field measurements. Therefore they will have to make daily weather forecasts and they should be particularly prepared to predict the phenomena which MAP concentrates on.

The case studies presented at this first meeting gave a good introduction into the goals of MAP. However, particularly the MAP cases were treated more from an analytical point of view than from a prognostic one. In order to improve the knowledge of the forecasters on the problems which can be encountered in the prediction of these phenomena it was agreed that all WG-FC members collect data on interesting cases. A selection of these cases will be discussed at the next meeting. The main goal of these case studies is to find out how often the models predict some remarkable event which does not take place or vice versa. Furthermore, the precision in the prediction of the location of these phenomena will also be discussed. The collection of the data will hopefully help the forecasters of the WG-FC to prepare for their work during the SOP.