Locally, up to 150 millimeters of precipitation fell in Zeeland last weekend, on top of the precipitation that fell earlier in the week. This caused significant flooding locally. Plots became empty. Areas that used to be the driest in the Netherlands are now faced with a lot of water.
The pattern has hardly changed since this spring: the south of the Netherlands always received little precipitation and extreme temperatures, while the middle and especially the north were better off. That situation quickly turned around last week. The south-west in particular has received a large basin of water, which caused local nuisance. This concerns a number of areas in Zeeuws-Vlaanderen and Walcheren.
low pressure area
It was expected in advance that a lot of rain would fall in Zeeland, but the situation turned out to be even more extreme. A narrow strip that stretched across Terneuzen and Middelburg, among others, resulted in precipitation amounts in excess of 100 millimetres. Official measurements of the KNMI are stuck at 72 millimeters in Middelburg, but locally quantities of up to 150 millimeters were measured. The reason for these extreme values is a small low pressure area (a 'furrow') where the rain fell very easily. The very warm seawater means that heavy showers can fall in the coastal areas, as could be seen in Zeeland on Saturday.
According to Stowa, the knowledge center for water boards, such rainfall intensity occurs once every thousand years. Last summer in Limburg even 200 millimeters of rain fell, but that was spread over a longer period. That it rained so much in Zeeland in just a few hours is extremely rare.
Consequences for the crops are still difficult to map. Potatoes that have been submerged for more than 24 hours are lost. Precipitation has major consequences for this crop in particular. Extra acidic when you consider that arable farmers first saw their crops dry up and now they are drowning.
Precipitation is too late
The monthly sum in the southwest is already reaching 100 millimeters in many places. That is positive for the green manures or the grassland. For potatoes, this precipitation usually comes too late, or it can have a negative effect if it encourages washing through. An advantage is that grubbling can be done without any problems. The rain is also too late for onions – almost all of which have already been harvested in the southwest. It refreshes sugar beets, but growers fear that the regrowth of leaves will lead to a lower sugar content.
Due to the recent rains, the precipitation deficit has again fallen below the 2018 line, with a current deficit of 281 millimeters. The KNMI expects this to increase slightly in the coming two weeks. We are now dealing with a new low pressure area in northwestern Europe, which will bring temperatures to 25 degrees and dry weather. Meteorologists also take into account a more changeable weather type, although this is not preferred in the current weather maps.
Heavy Showers in Coastal Areas
At the end of September, the volatility is expected to increase due to the influence of tropical storms. This can also cause temperature spikes, which means that we will continue to have summer days this autumn. Because the seawater is relatively warm, the chance of heavy showers in the coastal regions (coastal convergence) increases further. As a result, the east of the country receives less rain.
There is a good chance that this changeable weather type with alternating showers and summer peaks can also continue in October. Most weather models currently take this into account. It means that a weather type with a lot of precipitation is probably not in it, but stable summer weather is also not a scenario that is expected.
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