Winter 2020/2021 Forecast for the UK and Europe

Good evening! This is the winter 2020/2021 forecast for the UK and Europe. All thoughts are here mine alone and of no one's input. I’ve tried to explain the complex weather terms as easily as possible in this forecast so there shouldn’t be any problems with a lack of understanding with certain phrases. Without further to do, let’s get right into the forecast.

Here are how the seas are looking (provisional to the 22nd of November).

Let’s start with the Enso region. We have a moderate La Nina cranking through the enso region, it looks more central based than eastern based although over the past few weeks we have seen a small progression eastward with the sea surface temperatures. Nevertheless, It’s still a moderate central based La Nina which favours a mild or very winter.

Moving toward the NorthEast Pacific, we see cooler sea surface temperatures closer to the coast of America which is prone to rapid changes of temperature due to shallow waters but if we move a couple hundred KM south inside the cone, temperatures become much warmer. However, we have seen a quick cooldown inside this cone over the past few weeks. These waters are neither favouring a colder nor milder winter currently. Let’s watch to see whether those waters cool further in the coming weeks which then would be conducive for a colder winter.

Let’s move onto one of the most important areas in the sea to look at for our weather in Europe, the Atlantic. We see a slightly more +NAO pattern which favours the possibility for a milder winter. Average to cooler than average temperatures set themselves up across southern Greenland, we have a very warm Gulf stream and slightly above average across the temperatures across the tropical Atlantic.

Let’s move to the stratosphere:

Still this season, we haven’t seen a proper connection between the troposphere and the stratosphere which would really get the polar vortex ramping up. However now the modelling suggests that there will be a possible connection in the near future along with record breaking cold temperatures across the stratosphere for the time of year. This at some point through December should really strengthen the zonal westerlies. At the same time it should cool the North Pole where we’ve been seeing record breaking warmth. This strengthening of the Polar Vortex may act as a mechanism of finally seeing cold pools of air closer to Europe but may also act as a mechanism to bring wet, windy and mild weather through Europe if the NAO is positive at the same time of the strengthening of the Polar Vortex. It’s a bit of a double edged sword since currently it’s impossible to see any cold weather without cold pools of air somewhere nearby which we aren’t seeing at the moment due to the Arctic warmth but the strengthening may also enhance zonal westerlies with a +NAO bringing mild wet and windy conditions to much of Europe.

Finally let’s look at the stratospheric strength of the winds before I make the forecast:

The blue marker at the bottom of the screenshot is the approximate current date now. The black line in the middle of the shade of yellow is the average stratospheric wind strength from previous years. The yellow shading indicates the proportion of strength to the black line. If we find ourselves above or below the yellow shading at any point, we are at record breakingly positive or negative strength of the zonal winds. The red dashed line is last year's polar vortex strength where we saw an extremely mild winter across parts of mainland Europe. The purples lines are the forecast for the strength of the stratosphere, generally we see we are entering a record breaking phase of strength, we see above average strength forecast for the majority of the winter.

Winter 2020 Forecast

December: December holds the prospects of colder weather this winter especially across central and Northern parts of Europe. Western parts of Europe like Ireland and the UK may be more prone from the polar vortex trying to make inroads. This month will be a NAO neutral or -NAO month (a -NAO is low pressure across southern Europe) due to the ongoing moderate central based La Nina. Even though it’s more centrally based than eastern, I do believe we will pull off a -NAO since we also see signs of a Siberian ridge. We will also have a strong polar vortex which will in this case drive the jet south due to the -NAO allowing colder air to filter into Europe. Eastern and central parts of Europe will see a period of easterly winds at some point through the month, possibly entering western Europe depending on the strength of the polar vortex. One caveat is that for the first half of the month, the temperatures won’t be as cold as they usually would be with northerly or easterly winds anywhere across Europe due to the sheer warmth across the Arctic. Later in the month, when the Arctic cools, we may see the shots of air get colder. I expect a very dry month across central and eastern Europe, Scandinavia will end up closer to average with Britain and Ireland being wettest to average although it won’t be a desperately wet month even there. Temperatures looking slightly milder than average across Ireland and the UK, average across central Europe and Scandinavia, maybe slightly cooler than average across eastern parts of eastern Europe.

January: January will see a change from December. We gradually start losing that signal of a -NAO regime across Europe. This will allow frequent pumps of milder air through parts of Europe, especially western parts of Europe such as France, the UK and Ireland. The jet will start rising north starting to allow wetter weather to dominate the weather across northern and western Europe. Eastern Europe will take a week or so longer to get that milder more classic westerly pattern regime but it should also eventually turn milder there before mid month. We will be turning wetter than average across Scandinavia, the UK and Ireland, and slightly wetter across central parts of Europe. Eastern parts of Europe will be average to drier than average. It will be a much milder month than December and perhaps reaching an anomaly between 1c-2c above average in the UK and Ireland. Milder but closer to average elsewhere.

February: An early spring knocking on the doors. The positive NAO only strengthens and we see very warm conditions persisting across vast proportions of Europe. We should also see the jet move even further north which should allow for conditions to dry out a bit, especially across the UK. Portions of Europe may see anomalies 3c above average. A possible repeat of February 2019 on the cards!

In summary, It’s going to be a milder than average winter across all of Europe with the anomalies wettest to average in the west and driest in the east of Europe. It won’t be as mild as last winter in central and eastern Europe where we saw a record breakingly mild winter. The UK’s temperature anomaly for the winter will end up with an anomaly between 1c-2c above average. A slightly wetter than average winter as well for the UK.

Thank you for reading.

Stan

(My twitter handel: @Stanweather15)