Thread by @mikarantane

A major heatwave will hit this week to western Europe.
Temperatures over 40°C are expected in France and widely in Spain.

And this all will happen after a record-warm May in France and the 2nd warmest May in Spain.

Some thoughts in a thread 👇

The heatwave forms when an upper-level ridge strengthens in the downstream of the Azorean cut-off low.

The ridge involves hot airmass from Africa, and perhaps more importantly, descending air parcels adiabatically warming when reaching surface.

The evolution resembles 2019 western European heatwave, but this time the downstream ridge responsible for the heatwave does not grow as strong in amplitude, and also the wave breaking looks more cyclonic (or less anticyclonic) than in 2019.

Thus, I believe that this time we are not threatening national heat records as we did in June 2019, but in some places/stations the heat records will be broken.

And, there are still lots of uncertainty about what will happen after Saturday.

The heatwave, especially if prolonged, may have large implications for sea surface temperatures (SST) in Mediterranean and Bay of Biscay.

SST's are already now above-average across the whole Europe. #MarineHeatwave

And finally, naturally this #heatwave too is strengthened by climate change.

Increasing frequency, duration and intensity of heatwaves with global warming is perhaps the most established fact in the attribution science.