How could a flood happen last week

Our weather on Tuesday was affected by a very humid and unstable air mass. As a result, cumulus clouds and showers can easily form during the day. The reason for the instability was the existence of the so-called “argument line”. This is the line where different air currents meet. The convergence of winds along this line leads to increased air movements, which facilitates the formation of cumulus clouds, which have turned into severe thunderstorms.

The convergence line crossed our country in the afternoon and evening.

During the afternoon, the line of convergence with severe thunderstorms is constant across our country. Since there was little current in the atmosphere, the line also continued to kick into place. In addition, the convergence line was obstructed by a northwesterly wind on the northern flank, while a southwesterly wind was blowing on the southern flank. Due to the resistance of the air currents, heavy thunderstorms remained in the same place for a long time and immediately rained. Thus, thunderstorms on this line were accompanied by very high amounts of precipitation. In many places in Limburg, Flemish and Walloon Brabant, rain fell in torrents. At any given time there was as much rain as it usually falls in a month. The total precipitation in some places amounted to more than eighty liters of water per square meter.

Accurate weather models that calculate weather conditions with high computing power and accuracy have already estimated the situation very well. Weather maps have already shown the presence of the convergence line and the possibility of flooding in advance.

The ICONd2 precision weather model estimated the situation long in advance and calculated the convergence line with potential flooding.

Last Tuesday’s heavy rain caused a lot of inconvenience. In various places in Brabant and Limburg, the streets were flooded and mudslides appeared in the mountainous regions. Small streams and rivers turned into a churning body of water, and the water also flowed at full speed through many streets. As a result, many homes and basements were flooded.

Totals of precipitation measured at weather stations. In parts of Limburg, precipitation is more than 80 mm.