The Belgian Met Office has amended its forecast for today, Tuesday. A yellow weather warning remains in place but this could be scaled up to amber for the late afternoon.
Today expect an awful lot of rain sometimes accompanied by fierce thunderstorms. The Met Office is warning about flooding in places, especially in areas along the Dutch border in the provinces of Limburg and Antwerp, and along the German-Dutch border in the province of Liège.
Yesterday, a code yellow weather warning for thunderstorms was issued for more than half the country. This has now changed. Now there is the chance fierce local thunderstorms along the Dutch and German borders in the late afternoon and early evening (3PM to 9PM).
Dozens of millimetres of rain may fall in 1 or more hours. The Met Office is monitoring the situation and does not rule out issuing an amber weather warning later in the day.
"Storms or heavy showers on a municipal scale are difficult to predict shortly in advance," the Met Office said.
Code yellow means localised misery or damage, code amber points to larger-scale disruption or damage. In the provinces of Limburg and Liège, residents have already been hit by major flooding in recent days. As a result, the risk of flooding is again high as the ground is saturated.
So what can we expect?
5-20 mm of rain in many places.
Over 30 mm in Upper Belgium.
Up to 40 mm along the border with the Netherlands.
Why is the situation so difficult to predict?
A zone of rain and thunderstorms is currently making its way towards us from Wallonia, Lorraine and Alsace, reports VRT weatherman Bram Verbruggen.
Bram says current forecasts are none too reliable.
"It depends on the weather conditions. In Belgium we are experiencing a blocked weather pattern: dry periods and rainy periods alternate. Weather models have difficulty calculating when and where exactly the rain will fall".
Even apps that predict where showers will fall are not very reliable in this type of weather.
"Those apps show observations, measurements using radar systems. The rain you see in the app is the rain that is falling at that moment. What happens afterwards are future predictions based on weather models. These calculate what precipitation will occur. Every hour there is a new calculation and you have a new situation."