Slowly moving thunderstorms have caused a particularly erratic precipitation distribution over the past XNUMX hours.
Measured from 13 a.m. on Thursday morning, August 8, to this morning (August 14), 8 a.m. fell in large parts of the provinces of Utrecht, Zeeland and South Limburg, according to the official KNMI . precipitation map little or no rain, while more than 50 millimeters of rain was measured in many places early this morning in West Friesland and the head of North Holland. With an outlier of up to almost 100 millimeters.
KNMI map incomplete
The precipitation figures of the participating growers at the Boerenbusiness Crop and Roughage Tour and the site hetweeractueel.nl show a very erratic picture. Figures from 'amateur rain gauges' in Facebook and Whatsapp groups show that the maps of the geographical precipitation distribution that exist, even those of the KNMI, where measurements are taken according to strict rules with professional equipment, are not exactly complete. For example, the KNMI map lacks a small area near Winterswijk (Gld.) where, according to observers, tens of millimeters of precipitation fell.
Apparently these were relatively small-scale showers that grew to great heights and caused very heavy precipitation locally. For example, last night a thunderstorm with heavy lightning strikes from Germany moved north over the Montferland in the Achterhoek towards Zutphen. While near the Montferland eventually only a few millimeters of rain fell, half an hour later, less than 30 kilometers to the north at Zutphen, tens of millimeters fell in a short time. Hail or heavy wind gusts have not been reported.
Intense mix of hot and cold
Weerboer van het Oosten, Gerrit Vossers (Silvolde Gld.) received many reactions on his Facebook page about the precipitation amounts. When studying the amounts of rain that farmers and citizens share on his Facebook page, the picture emerges that the amount of rain per 100 meters can increase by a millimeter or more. "Apparently, these kinds of showers continue to grow as the cold air above mixes with the warm air on the ground, creating a self-reinforcing chaotic airflow effect and localized heavy rainfall."
That is also the image that arises in the slightly more northerly Salland. The thunderstorms last night caused differences of no less than 100 millimeters of rain a few tens of kilometers away, cattle farmers Rudi Haarman and Jan-Hein Nikkels report on Twitter. In the early morning in Friesland the same story, whereby the direction of migration was to the west and not to the north.
Slow pulling showers keep coming
In the coming days it will remain warm in summer but also changeable, with a high chance of locally heavy thunderstorms. The showers also continue to pass slowly. Not much movement in the air. The chance of thunderstorms will decrease after the weekend.
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