25 July 2019 – Another memorable day

Yesterday I wrote a blog about the high temperatures in the Netherlands and the breaking of all existing temperature records. Today it continued and for the first time ever, temperature in the Netherlands rose above 40 °C. First time ever means since formal measurement began in 1901 and even since historical measurement series spanning almost 300 years.

So, today at 16h30, temperature distribution in the Netherlands was as follows:

Temperature distribution 25 july 2019

Temperature distribution 25 july 2019

There are two interesting remarks to make about this day:

    1. Around 14h00, a message came that at KNMI weather station Deelen (near Arnhem) the temperature suddenly had crossed the 40 °C boundary and was set at 42.1 °C. Immediate doubt about this value was a bit later confirmed by the KNMI: apparently only one of the two sensors had measured, the other did not. This hardware problem invalidated the measurement. Only about an hour later, airport Gilze-Rijen confirmed the passing of 40 °C and the daily maximum stabilised at 40.7 °C. 25 of 37 KNMI stations registered records in the range of 36.1 °C to 40.7 °C on this day.
    2. Official KNMI Station Nieuw Beerta, 17 km ESE of Wagenborgen, nearest to my PWS, my PWS and PWS ‘t Zandt at 17 km NW of Wagenborgen, registered their daily maximum as 37.9 °C, 36.1 °C and 34.3 °C  respectively.
      Those are pretty big differences on such short distances but they correspond well with the temperature distribution map above. We can see that, from the Lauwerszee land inwards, the temperature gradient is more than 8 °C over a distance  of only 30-40 km. Locally, at my station, I measured sudden sea wind and a temperature drop. It seemed as if no record would be made today and it was only around 17h00 that the 36.1 °C record was set for only 5 minutes.

The above shows, local meteorology through PWSs does not hold truth. It is the view of three or more stations in a radius of roughly 50 km, which gives knowledge (which is of course why the KNMI has 37 stations in NL).

If predictions are right, the heatwave continues for another 2 or 3 days but with temperatures below 35 °C. After the coming weekend temperatures will drop to 25, a drop which may be accompanied by some thunder and rain (but not much). I will report if the weather situation becomes anomalous.

An interesting article on heatwaves (in Dutch) and the KNMI measurement series can be found on the blog Klimaatverandering.


[Edit 26 July 2019 ] :

After the night I found the following reactions on twitter, some of which may be interesting.

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