European Winter Outlook 2019-20

I am back with a European-specific forecast, that caters to people watching weather patterns and snowfall across Europe, from the UK to the Alps, to Southern Europe.

Model Outlook

The combination of seasonal models provided by Copernicus leads us to a +NAO scenario, which would bring a wet/mild winter for the UK, possibly decent snowfall for the Northern Alps, and a poor snowfall season for Southern Europe.

QBO

13bbhFZl14.png
All the years that fit my current forecast for +5 to -10 for this season for QBO values at 30mb, minus strong Ninas and Ninos.

Above is my QBO analog for winter 2019-20. These factor in years that fit within the QBO value range that I am forecasting this year (roughly based on the forecast below).

qbo_wind.jpg
FU Berlin University

My QBO forecast for the next year is the red line in this image.

Key trends to note, based of this:

  1.  -NAO, deep Greenland high.
  2. Massive European trough.
  3. Deep troughing around Eastern US.
  4. Aleutian ridge.
  5. Eastern US pattern driven by NAO.

Probably not the most sturdy patterns imaginable indicated by the composite. But certainly a pattern that could drive snow and cold for the UK, the European Alps and the rest of Central and Southern Europe.

ENSO

Our current oceanic situation in the Pacific is a weak mainly Central Pacific El Niño, as presented below.

The pattern by the oceanic standard would be something like this:

So we see obviously deep European troughing in Southern Europe, making the Southern European Alps and the rest of Southern Europe big winners snow wise with troughing.

Typical Nino effects on Europe tend to be good for increased precipitation for the UK and the European Alps, but they also help to produce -NAO patterns and SSWs that can help bring cold and snow to these regions. These effects tend to amplified most when the Nino is weak-moderate and in late winter.

From an atmospheric state, we are currently in a GWO orbit for the past few months in the negative AAM values. This approach in the extratropics also sees a -NAO and European troughing.

Here is a composite for -AAM winters (sorry for the poor viewing of Europe, but you can see the rough troughing)

My take away for the GSDM pattern this season is a neutral to weak-moderately -AAM circuit this winter, particularly in early months. This pattern is good for meridional patterns that benefit the European Alps, especially the South, and places like the UK.

But as you can see, it is less amplified than the straight Modoki pattern. For this reason, and the intraseasonal effects of ENSO, I can see a favourable pattern from ENSO early on, and an even more favourable pattern later on, per ENSO effects.

Sea Ice and Snow

The Barents-Kara Sea is currently seeing an ice recovery bucking the weak sea ice trend of the current century. However it is still slightly below the 1981-2010 climatological trend. This may result in a somewhat of a +AO response compared to recent years, but I can’t see this being a strong influence, given it’s still below the mean.

The significantly lower than average sea ice anomalies in the Bering Sea right now and expected to continue into winter are expected to assist in ridging in the Aleutian region. This is probably on the wrong side of the globe to have too much impact, but it’s negative if anything.

Taking statistics just after the end of October, Siberian snow extent is higher than normal, which helps invoke a -AO situation and helps the development of a SSW. The Siberian High is already gearing into winter mode. One red flag is recent lower than average snow coverage close to Southeastern Europe, which may be a negative sign for the early winter ahead for that part of Europe.

North American snow cover is also higher than normal, which possibly would help deeper cold to come across the Atlantic.

Solar

Solar impacts for this year will be indicative of a higher chance for a -AO, benefiting European snowfall in the UK and Central/Southern Europe including the European Alps.

Atlantic

I am not a big user of the Atlantic for forecasting, but for the British and European blog readers, here we go:

The cold “blob” in the North Atlantic may allow for a colder winter for the UK and Europe as a whole. So it’s good for snowfall, especially lower down, but may reduce precipitation a bit.

The warmish SSTAs around Italy in the Mediterranean may be useful for Southern Alps snowfall/precipitation. It can also mean warmer temperatures however.

Stratosphere

I see a more likely chance than normal for stratospheric warming this winter. Why?:

  1. A descending -QBO will help chances for a SSW later on this winter, particularly for February.
  2. Brewer Dobson Circulation is to be stronger than normal in both of the NH and SH subtropics and average over the tropics this month. I expect a stronger than normal BDC over the winter. This increases ozone in the SPV during the winter.
  3. ENSO factors are sort of supportive at least from the oceanic perspective. The GWO should be more supportive later in the winter. 
  4. Higher than normal Siberian Snow Cover supports a SSW during this winter.
  5. Solar minimum is taking place at this point, favouring a -AO and potential stratospheric disruption.

This means that I predict a SSW from mid Jan – early March. Current signs of stratospheric weakening could eventuate into a minor SSW with some medium-long term implications, but I think the major event will be later in winter. The implications of this is more snowfall for the UK and for the European continent including Southern Europe.

The above graphic indicates EC is favouring a SSW or a Stratospheric disturbance of some sort in January and February. UKMO still thinks it will be stronger than normal per the mean, but some ensemble members are having more interest in the idea of a stratospheric disturbance.

Conclusions

This has been a hard one for me with various factors in play here. But running composites and all of the drivers through the methodology have got me firm on this map below:

  1. December is expected to more average like.
  2. January and February will be the months that define the image to look like this, the strongest months of the winter.
  3. Scandinavia should expect lower than average snowfall.
  4. UK should expect above average snowfall throughout winter IMO, with the best of the falls in January and February. The falls will be less climatologically significant in the highlands, but it should ultimately be a snowy and cold winter, presuming extratropical and stratospheric forcing goes our way.
  5. The Southern Alps should expect a very good snowfall season, based on a more equator-ward jetstream.
  6. The Northern Alps should expect an average-above average season.
  7. Eastern Europe should expect a colder and snowier than average season.
  8. The Pyrenees should expect an above average snowfall season IMO.

And here is my snowfall anomalies map for illustrative purposes.

Thanks so much for reading. 

Seasonal outlooks tend to have bias and errors, due to the fact that these forecasts are so far out. So don’t use these outlooks to make important decisions. These outlooks is meant to be interesting information, that can help to see what the season would be like. 

This took a lot of work over the last fortnight, so I appreciate your support. Starting in late November, my long range outlooks for North America will start! They will be produced every 2-3 weeks, looking out into the range of 10-30 days out. Stay tuned. 

Thanks again for reading, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above

One thought on “European Winter Outlook 2019-20

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