Next week’s situation is still very uncertain. Numerical forecasting models “slip” with the very uncertain course and dynamics of the Atlantic recession. Some models have several cold drops coming one after the other, sometimes without reaching us, while others see a cold drop located on the outskirts of Ireland and Brittany. Consequences: There are completely dry conditions, others very heavy rains and storms, some in between. Let’s try to clarify this.

First of all, it is important to remember that the articles we write are conditional: we expose the results of models that are constantly evolving. As we often say: Take a pinch of salt and approach predictions with caution, especially at such times. Here’s the difference between yesterday’s models (see map below left) and today (see map below right). Monday, September 6, 2021 The difference between the two models (GFS model) is significant:

Yesterday, the GFS model (like the CEP) isolated a cold drop of low pressure near the UK with strong dynamics. These models were usually taken over by set-makers, which is a sign of moderate good reliability, however the time limit is still a long way off due to scrutiny (D6). And yet … today, the same model sees much less dynamic cold, which is isolated from Portugal. The second acts as a “heat pump” for France, where we move from a very rainy situation to a dry and hot one.

But can we assume that these new models are reliable? Below is the standard variation of the various set predictions (American with GEFS, European with ECMWF / CEP). The finding is clear: the uncertainties in the previously mentioned area are still very large: near the Atlantic / Ireland. To be clear: As the models evolve, be careful not to turn into the opposite thinking that the prediction has stopped. This is not the case. It takes more days to see where we are going, especially since other factors are pushing us into observation.

Critical CEP and GFS conditions are more favorable than the turbulent weather seen yesterday. Their set designers, on the other hand, are different, depressors follow each other more dynamically and constantly isolate themselves with our areas. Below, there are possibilities for instability and precipitation for the D5 / D6 horizon. We took the 500 / JKG limit

What we clearly think is that we are going into an unstable time, maybe in several stages, maybe late episodes. Today’s high pressure signal from GFS and CEP seems impossible but not impossible. We’ll be back tomorrow …