*Winter 2019/2020* Meteo-France Model forecast from October
Meteo France is the French national meteorological service. They provide official weather forecasts and warnings for France, but also have a global medium range and long range weather modelling system.
The long range forecasting system from Meteo-France is simply called Météo-France System 7. It is the 7th generation of their long range modelling system, actually having its first forecast done this month (October 2019). So we will be looking at the very first operational forecast, of the brand new generation of the long range modelling system from Meteo-France.
All these forecasts are an average picture over 3 months (Dec-Jan-Feb), and show the general prevailing weather pattern. Even if the models would be completely accurate, it does not mean that such weather conditions would last for 3 months straight. There can still be cold fronts and snowfall in between such milder patterns in the mid-latitudes. The difference is that instead of the usual 10-20 snow days for example, you only get 3-6 snow days (as an example). So the models don’t suggest what the weather will be like for 3 months straight, but just how it might look 40-60% of the time.
Upper level forecasts.
We always want to know how the pressure forecasts look like. That tells us a lot about the overall global circulation and weather patterns. You can learn more about the importance of long range pressure forecasts in our previous post, that contains basic information that you need to know about long range forecasts, and graphics from the September model runs to compare:
Just like ECMWF forecast, the 500mb geopotential height forecasts from Meteo-France is not really optimistic if you are a fan of winter from Europe or central/eastern parts of USA. In fact, it is kinda the worst-case scenario for winter fans. We see a deep broad low in the North Atlantic, surrounded by the “highs” from east USA across the Atlantic into Europe. This is probably the most classical positive NAO pattern that you can see on the long range forecasts. This is a typical pattern for windy and wet weather across the UK and Scandinavia, and mild conditions across central/southern Europe. In the USA, we have warmer and drier conditions in the far east, and mild and more wet in central/southern parts. Unlike the other two European models, UKMO and ECMWF, we can see that the deep low in the North Atlantic is actually further north, which in turn has even warmer and drier central/southern Europe.
Staying at altitude, we have the 850mb temperature forecast, which is on average around 1.500 m altitude in the mid-latitudes. Here, we can see what we expected from the 500mb height forecast. Warm conditions across Europe and east USA, without any hint of colder altitudes in the two continents, except for eastern Canada.
Going down to the surface, we start with pressure again. This shows the pressure anomalies at the surface, which are more influential for surface wind conditions and temperature transports. Here we see the entire North Pole is under low pressure (positive AO – Arctic Oscillation), which means the coldest air is locked inside the Arctic circle, and is harder for it to move towards south into Europe for example. That is a typical sign of a strong polar vortex. Over most of Europe, we see a broad high pressure area, and the west air flow across the UK and Scandinavia, just as expected from the general circulation forecast above. This means stormy weather for UK and Scandinavia, with less chance for easterly conditions and so less chances for colder weather in UK.
In the USA, we can see a low pressure signal, which drives the warmer westerly/southerly flow on its south and east side. But at the same time it can promote more northerly (and potentially colder) flow across the western parts. But there are no hints of that as we will see below.
One of the most used long range parameters is of course the 2-meter temperature anomaly forecast, also simply referred to as the surface temperature forecast. It is the main forecast to tell us what to expect in terms of temperatures (warmer/colder). As we have interpreted already from the charts above, Meteo-France is the worst-case scenario for winter fans in Europe and USA. Warmer than average across Europe and most of the USA. We can see large parts of the polar circle in above average temperatures, which is perhaps a bit questionable to this extent, but not impossible with the low pressure across the entire region and west flow on its outer perimeter.
To summarize, the Meteo-France forecast from October shows a typical positive NAO/AO pattern, with milder winter in Europe and USA.
We still have the stratosphere as a major factor. Long range forecasts are generally not as good at forecasting stratospheric dynamics in detail, which means they tend to underestimate any potential sudden stratospheric warming events (SSW’s), since the final forecast is made out of many individual calculations, which have different ideas about the stratospheric development. An SSW event can have a major impact on the circulation and can cause major pattern changes in the Northern Hemisphere. So a potential SSW event is an important factor that can change the course of winter in either way across the North Hemisphere.
There are more long range models waiting to be explored, so click below to go back to the model selection page: