Early September Seasonal 2019-20 Winter Preliminary Outlook

Hello to all of our Northern Hemisphere readers. Winter is officially coming, and it’s time to start having a look at it. It’s important to note that this is quite early, and it would be a good idea to follow through to the main November seasonal forecasts.

Model outlooks

Above is the forecast from the American CFS model. It features a Aleutian low quite close to the North American continent, promising signs for Western North America. Less great for Eastern North America with a high over most of the NA Continent. A Greenland-Baffin low combines with an Azores high for a +NAO setup with potential increased snowfall to the Northern Alps. We also see ridging over Siberia and Japan as well, which isn’t great for it’s snowfall.

Corpernicus Program, EU

Above is the C3S multi-model ensemble featuring data from the world’s best models the ECMWF and the UKMO models, as well as a few other inputs from the French, Spanish and German models. It casts a similar picture to CFS with a Greenland low and an Azores High (+NAO). It has a particularly strong Siberian high, and better Aleutian heights for Japanese snowfall. It has a +PNA high which also extends over most of the continent into the East.

ECMWF

I just wanted to finish with this from ECMWF alone. Good positive heights occur to the NW of Japan, a strong Aleutian low. It also shows a strong Baffin low, with more promising troughing towards the Eastern US, as opposed to some ridging in the West. Also revealing a largely +AO pattern.

ENSO

Currently we are in a warm neutral ENSO phase. The consensus of the international modelling predicts that this will continue into the winter for the Northern Hemisphere.

This means a more meagre influence from ENSO this year in theory.

This is confirmed by ECMWF with limited warm SSTAs in the Nino region. There are warm SSTAs north of the Equator towards the North Pacific, that would fuel Atmospheric Rivers and perhaps a +GLAAM, but as far as Oceanic ENSO goes, it looks pretty neutral. CFS shows warm subsurface heat growing in January and coming to the surface as some sort of Modoki Nino in Feb, so if anything happens it would be a borderline-weak Nino. For now, I’ll maintain a warm neutral stance.

QBO

We have a easterly QBO descending at this point. I forecast it to be down to 30-40mb by the end of the year. This would show a growing influence positive for snowfall in Eastern US, Japan and much of Europe.

NASA

As the westerly phase continues to descend in the lower parts of the QBO domain, the effects positive to the Western US will remain, but wane in favour of the easterly phase as winter carries on.

PDO

Over the years, this has evolved into a general North Pacific forecast, but it still remains known as PDO. On that note, EC and most models show a strong Aleutian Low.

However I can see a case for at some form of a -EPO during the season, particularly earlier on. There is considerable warm SSTAs around Alaska and the Bering Sea, and their impact is sort of shown by this chart with some positive anomalies. But I believe there could be a deeper ridge, particularly if there is a good early Alaskan snowfall season. Overall the Aleutian low being deep would be good for the Western US, and Japan as well.

Snow & Ice

Ice coverage is currently lower than normal in the Arctic, but this isn’t really important for this particular seasonal forecast. We are more interested in October and November ice cover. What we do have is Greenland snow and ice data to use.

This chart shows lower than normal amounts of light being reflected by Greenland’s ice pack and specifically the snow on top of it. This means less chance of a high being curated by the albedo effect, which would not help a -AO and particularly a -NAO setup, which would be poor for Eastern US, Europe and Japanese snowfall. Instead we see this as a more +AO influence. This is data from the last week, and there is a long way to go, so let’s see where the next few months bring us.

MJO

The yearly edition of the CHI 200hPa charts is back.

We see a big Phase 7-8-1-2 influence here, which is positive for Japan and Eastern North America snowfall. Obviously quite of an opposite phase over Australia, SE Asia and the rest of Maritime Continent. The MJO seems quite strong in this chart, so perhaps it can have a bigger influence with a more neutral MJO.

Stratosphere

CFS shows a weaker than normal stratosphere to start with this year.

That would be good for a SSW, subsequent -AO, and increased snowfall in the Eastern US, Europe and Japan. What is also good for it is a strong ozone presence in the SH ready to go to feed to the NH later in Spring.

Solar

And a familiar mention of the -AO influence in the solar minimum we are currently in. The solar minimum is at it’s peak, and will very slowly head towards the solar maximum over the next five or so years.

Conclusions

So our initial outlook starts to see certain things:

  1. A strong winter Aleutian low
  2. A +NAO favoured by models and Greenland ice cover.
  3. Perhaps some -EPO blocking
  4. A warm neutral ENSO state.
  5. A good outlook for Japan, Northern Alps and Western North America
  6. An opportunity at a decent winter for the Eastern US, per some indicators.

Thank you so much for reading this seasonal outlook for the Northern Hemisphere.

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 are meant to be interesting information, that can help to see what the season might be like.

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.

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