Why the deadly floods of November 1999 in Aude were part of the big bang of “vigilance” Météo France

Did the floods of November 1999 in Aude, but also neighboring departments, have an impact on Météo France's practices in terms of prevention and announcements of extreme weather episodes?

With the storms of 1999, Lothar and Martin (which hit the North then the South of France on December 26 and 27, causing 92 deaths, Editor's note), it is one of the major events which initiated the discussion between the Ministry of Interior and Météo France for the implementation of vigilance. Even if each year brings its share of new things, the floods of November 1999 and these two storms changed many things in practices and decision-making tools. Even if we must remember that Météo France only has a warning role: we are scientists. Everything relating to alerting populations and sheltering actions is the responsibility of the crisis management authorities, with the prefecture in the lead, at the level of a department.

The chronogram of the events of November 1999 makes it possible to list all the BRAMs issued by Météo France, the regional weather alert bulletins: what has changed?

These BRAMs were only intended for prefectures, firefighters and institutional stakeholders, but the general public did not systematically receive feedback on this information. 1999 raised awareness of this lack of information, particularly in relation to the danger that these exceptional weather episodes could represent. Vigilance intended for the general public, with four color levels (green, yellow, Orange and red), division by departments, and the display of the maximum level of vigilance for the next 24 hours, was put in place on 1^is October 2001, with the 1^re map for avalanches, snow-ice, high winds, and thunderstorms. The procedure has continued to expand, with new vigilance: the heatwave in 2004, following the summer episode of 2003, the extreme cold in 2005, or the “rain-flood” vigilance in 2007, with the support of the Vigicrues network. The storm of Météo France dedicated to vigilance, is based on the flood forecasting service (SPC) and the central hydrometeorology and flood forecasting support service (Schapi).

How was this tool designed, with what objectives?

Firstly, starting from the principle of a map, with a very simple color code, and a pictogram to indicate the nature of the phenomenon. In the event of orange or red vigilance, a monitoring bulletin is published, at least twice a day, at 6 a.m. and 4 p.m.: these times were initially decided to allow their publication in the evening and morning dailies. But the update can be carried out more regularly: if a stationary rain phenomenon is in progress in the plain, we can update every two hours. Over the years, other tools have appeared, such as D-Day cards and D+1 cards, but also a “next days” tab on the site, which allows you to indicate the probabilities of going into vigilance. , from D + 2 to D + 7.

Do you think that the general public is aware of the existence of these tools, and what is your view on the criticisms that can be made, in particular on the repetition of vigilance?

The population in the South is aware, at least I hope so. What's important is to check the tracking bulletin and stay informed. Unlike other forecasting organizations, I would like to remind you that Météo France, as a State service, is subject to an obligation of results. Each episode of vigilance, from the orange level, gives rise to a quality control, and an annual report on the effectiveness of the vigilance is published. The latest report published on meteorological vigilance, for the year 2022, made it possible to measure the relevance rates, and the early detection rates of more than 6 hours