Rain cloud anomaly south of France, can someone explain?

  • | Premium

    Hi there (bonjour tout le monde!)
    Since august 2020, south of France (area between Montpellier and Marseille) has seen a huge amount of rain days or very cloudy days, which is very unusual (mediterannean climate is rather dry and no clouds). Lots of lows centered near portugal and spain seem to causing the rain, but usually lows are centered in Biscay, and hit the north of the french west coast. It's been more than 6 months now that the weather is rainy and cloudy with these lows centered way more south than usual, and often moving across spain into the med ( more rain...). Does anyone knows what is causing these lows to be so down south and able to go across land (Spain/Portugal)?? The jet stream seem to have been very low down south, but what is causing the jet stream to be at such a low latitude??

    If anybody knows, thanks a million to share! :-)

  • Meteorologist | Premium

    Your question is more related to climatology than weather forecast

    The large scale atmospheric circulation in our latitudes is characterized by fluctuating jet streams between different
    quasi-stationary states, called weather regimes. The best known one is the famous zonal regime : this regime brings extratropical cyclones (depressions) over Europe and is especially responsible of storms during the winter.

    During the last months, we observed a blocking regim with anticyclonic conditions in the North, forcing the cyclones coming from the West to go down and pass by the South of Europe generating a lot of regular rain like in the South of France. On the contrary, we observed a very dry situation in the North of France and Belgium with almost no rain during several months in a row, which was unusual.

    On top, there were also several situations called cut-off or « goutte froide » on Spain, Portugal and Atlantic sea generating a stong warm and humid wind coming form the South. This warm and humid air advection, covered by cold air in altitude, created convection and therefore huge thunderstorms in the South of France.
    The position of the jet-stream and his strength is playing a role in this situation

  • thanks for your response

  • thanks man

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