Winter 2021/2022 Forecast

HEADLINE: Alternating Warm and Cold

Good evening, welcome to the 2021/2022 winter forecast. This will be one of the tougher forecasts I have been made to do with various options on the counter leaving multiple scenarios a forecaster has to choose from, which is far from ideal.

The oceans are the primary factor I look at before making my forecasts. As of the 30th of October, we have a familiar pattern in the oceans. We currently have a La Nina signal, a negative PDO (pacific decadal oscillation) and an incredibly warm Atlantic most likely to due another very active hurricane season transporting warm waters from the Tropical Atlantic to the North Atlantic.

The most relevant years I have picked out for my forecast are the Autumns of: 1995, 2005, 2007, 2011.

All four years contain a La Nina event, the difference being the Autumn of 2007 has a moderate to strong event whereas the other years were more in line with our current year La Nina values. All four years contained a -PDO, the difference being the year 1995 had monthly variations with its PDO values switching from slightly positive to slightly negative and neutral. All four years also were in a -QBO, 2007 and 2011 were at the strongest point of their cycle during Autumn whereas 1995 and 2005 were just about starting their cycle in the Autumn. All four years contained above average or exceptionally above-average hurricane seasons including 2005 (the record holder for the most number of hurricanes within a season). Looking at reanalysis, 2021 also resembles the 500mb height anomaly superbly for 2005, very well for 1995, 2007 and well for 2011.

The Autumn of 2021 fits within all these hallmarks of the years 1995, 2005, 2007, 2011.

Most interestingly, the Autumns being analysed all contained sudden stratospheric warmings (2011 maybe debatable) which may be a precursor the atmosphere is in a good state to deliver another major warming in the stratosphere this winter.

Here are the following year's sea surface temperatures from the 30th of October:

1995 -

2005 -

2007 -

2011 -

Now for comparison with 2021:

All the above years are very similar in the profile and set up of the sea surface temperatures with our current year.

Statistics and Figures

The following averages of the winters of the years being analised, for the UK (1981-2010 avg):

UK: 95/96 DEC: -2.4 JAN: -0.3 FEB: -2.1 (COLDER THAN AVERAGE)

UK: 05/06 DEC: -0.3 JAN: +0.3 FEB: -0.9 (COLDER THAN AVERAGE)

UK: 07/08 DEC: +0.2 JAN: +2.0 FEB: +0.8 (MILDER THAN AVERAGE)

UK: 11/12 DEC: +1.3 JAN: +0.8 FEB: -0.8 (MILDER THAN AVERAGE)

The following averages of the winters of the years being analised, for Poland (as a reference for Central European/Eastern European weather patterns, 1981-2010 avg):

PL: 95/96 DEC: -4.23 JAN: -3.91 FEB: -4.55 (COLDER THAN AVERAGE)

PL: 05/06 DEC: +0.26 JAN: -5.44 FEB: -2.05 (COLDER THAN AVERAGE)

PL: 07/08 DEC: +0.83 JAN: +3.04 FEB: +3.96 (MILDER THAN AVERAGE)

PL: 11/12 DEC: +3.14 JAN: +0.89 FEB: -5.14 (COLDER THAN AVERAGE)

As you can see, we have conflicting signals with winters. Even though with very similar atmospheric setups, we find strong discrepancies with 1995/96 being a very cold winter on the other hand we have 2007/08 which turns out to be extremely mild.

What 2007/08 has that differentiates it from other winters is both the strongest signal for a -PDO but also the strongest La Nina by quite a margin over other years. When a La Nina becomes too strong, it tends to override other atmospheric factors, which looks like what happened in 2007/08. It was known to be a very atlantic driven winter. For this reason, It should not be discarded as a potential player for our upcoming winter but it may be considered as a less significant player in the forecast.

What makes 1995/96 and 2005/06 such cold winters, in my opinion, is the development of a ‘tri-pole’ in the Atlantic through the winter which was not present during Autumn. A tri-pole is when we have a band of warmer followed by cooler followed by warmer sectors in the Atlantic Ocean. This is exactly what happened in both winters, particularly in 1995/96:

Sudden Stratospheric Warming

With our small but maybe significant (for future reference) warming in the stratosphere this October, it’s a sign the atmosphere is conducive for future warmings in the stratosphere for this upcoming winter. As well as this, all four analogue years have had sudden stratospheric warmings that either destroyed or displaced the polar vortex. It’s a clear signal for a sudden stratospheric warming at some point this winter.

Summary before the forecast

Out of the four years, I favour a mixture of winter 2005/06 and 2011/12, simply because 1995’s -PDO isn’t as strong as 2021’s and 2007/08 has a moderate to strong La Nina. However small chances of outcomes regarding 1995 (if a strong tri-pole develops) and 2007/08 if the La Nina suddenly decides to rapidly strengthen as well as the -PDO. However, I’d give both outcomes a 10% chance of development.

Winter 2021/2022 breakdown forecast

December: The 1-2 weeks will be characterised by frequent northerly incursions for the UK and Ireland, this will be introduced by a cold front from the North. The northerlies will generally come as quickly as they go with high pressure toppling over bringing some frosty nights. On the other hand, central and eastern Europe as well as parts of Scandinavia will be pulling up very mild southerly winds, it will also be very wet for portions of Central and Eastern Europe. By week 3, a break in the ‘toppler’ pattern will give way to a period of mild and wet weather in the UK, this period may be characterised by some unusual storminess not seen in a couple of years for the UK. Central and Eastern Europe stay generally mild or return close to average but a big cooldown compared to weeks 1 and 2. Week 4 will see the mid-Atlantic ridge come into play again with the orientation changing to an NW tilt allowing some colder winds to surge back into the UK and Ireland, there may be some winteriness on lower levels in the West of Ireland and the Uk. Central and Eastern Europe will see that jet stream push further South allowing for some diving areas of low pressure, on the northern edge it will be cold enough for snow.

UK/Ireland: December will be close to or average with temperatures as well as average or slightly wetter than average rainfall.

Central/Eastern Europe: Above or significantly above average month in terms of temperature, rainfall will be close to average.

January: As we go through January, a theme will develop of heights trying to rise across Scandinavia and Western Russia, this will start pulsating colder temperatures particularly across Eastern Europe. Nevertheless, the 1st week of January will be high pressure dominant for most of Europe including the UK, the further east you are the colder the temperature departure will be whereas the UK may be reaching double digits by day although nighttime temperatures will be chilly. The majority of precipitation will be across Scandinavia. Between the second and third week, central and eastern Europe will have their first very cold spell of weather but it will be mainly high pressure orientated. The UK and Ireland will be faced by SW winds as low pressure tries to move up from Spain and Portugal being blocked by high pressure to the NE of Europe. The 4th week will feature a breakdown of the cold weather for a time across Central and Eastern Europe whereas the UK and Ireland will again feature in a quick northerly shot from a toppling ridge across the country, the air may be cold enough for snow if the isobars are tight enough.

UK/Ireland: Slightly milder than average month, drier than average conditions dominating in the East with average or wetter than average conditions in the West.

Central/Eastern Europe: Average temperatures, drier than average conditions dominating.

February: With confidence, this month will be the coldest month of winter across Central and Eastern Europe. At some point through the month, winds will go into a very cold easterly. The UK and Ireland will also have a decent chance of pulling these bitterly cold winds in but the main focus of the cold will be across Central and Eastern areas. There's a strong signal within the analogues that February will be the most ‘blocked’ month, particularly across Scandinavia rather than Greenland. If high pressure was to retrogress towards Greenland, the UK and Ireland would have a much greater chance of significant cold although this is a less likely scenario. I don’t see this month being westerly dominant in any European region. With this said, there will be short milder episodes across the UK and Ireland, Central and Eastern Europe will be locked into cold and milder episodes are not favoured.

UK/Ireland: Average or slightly below average month temperature-wise, drier than average month.

Central/Eastern Europe: Significantly colder than average, average precipitation.

Summary

UK/Ireland: A relatively mixed winter with mild and cold episodes alternating. This winter will again not feature much storminess apart from week 3 in December. Although December will feature multiple northerly shots of air, February will be the most potent month with potential to bring the coldest and most severe weather, however, it will not be as cold to average compared to Central and Eastern Europe. January will be the mildest month of winter with high pressure trying to dominate.

• Temperatures will be slightly milder than average.

• It will be a slightly drier than average winter.

• Highest widespread snow potential is in February.

Central/Eastern Europe: A backloaded winter, starting very mild and becoming progressively colder. The mildest weather will be in December and the coldest in February. January will feature the first hints of a very cold February although it will be moderated cold.

• Temperatures will be average or slightly colder than average.

• Average precipitation.

• Bitterly cold February.

Thank you for reading,

Stan