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*Winter 2019/2020* JAMSTEC Model forecast from October

JAMSTEC is the Japan Agency for Marine-Earth Science and Technology. It is engaged in a variety of research and development activities as one of Japan’s research institutes, covering a broad spectrum of marine and atmosphere science and technology.

Aside from researching marine life and the circle of life, they also produce their own long range weather forecasts. Their long range modelling system is called Sintex-F.

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. 

You can learn more about the importance of long range 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:

Winter 2019/2020 early look (September) and LONG RANGE THEORY.

Surface levels

There are no pressure forecasts available from JAMSTEC, so we will focus on the very basic maps, temperature and precipitation anomalies. 

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). The temperature forecast from JAMSTEC is very interesting. It is unlike any other long range forecast we have seen. The colder air over east USA and west Europe, hints at two distinct low pressure areas, one over central Europe, and one over west Atlantic/east-southeast USA. This is so far the most optimistic winter forecast for Europe and east USA, since all other long range systems tend to focus average or colder conditions into parts of west/northwest USA only. 

JAMSTEC 2-meter temperature anomaly forecast. Image by: JAMSTEC

Looking at precipitation forecast, we have more precipitation over much of Europe, except for the southeast parts and UK. Such a scenario, combined with the temperature forecast above, would mean more snow for central Europe, especially the Alpine regions and northern Balkans. We don’t see colder temperatures over the Alpine/north Balkans region, but it is in the “war zone” between the cold and warm air, which usually drives the secondary cyclogenesis and brings snow to the region. In the USA, we have more precipitation over southeast parts and the east coast, which together with colder temperatures would indicate at above average snowfall.

JAMSTEC precipitation anomaly forecast. Image by: JAMSTEC


To summarize, the JAMSTEC forecast from October is fascinating, since it is rather unique. It has colder temperatures over western Europe and east USA, combined with above average precipitation. That usually indicates at least average snowfall if not even above average.

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: