Australian Snow Season Outlook 2021

Welcome to our primary outlook for The Australian snow season. First however a few announcements are required:

  1. Unfortunately the long range outlooks during the season (in all regions) will be discontinued. COVID, time constraints and other factors have meant that it is no longer viable. However I will still be talking about long term drivers (during the snow season) on my twitter handle @longrangesnow, and on various snow/weather forums. And it does not mean the end of these seasonal forecasts on this blog.
  2. ## IMPORTANT FOR EMAIL SUBSCRIBERS ## my email subscription service through Feedburner will end in July. If one wants to keep email notifications for my seasonal outlooks and other possible content, please subscribe using the new “Subscribe Via Email link” on the tab above. I appreciate your support on this matter.

Okay now we are through that, please enjoy my outlook for the Australian snow season.

Verification

So for the sake of transparency and improvement, I am reviewing my past predictions. And they haven’t been great particularly last year. So one might ask what I am going to do to improve.

2017 “average season” > a very good season

2018 “slightly above average season” > a good snow season.

2019: “average season” > ended up being a pretty good season.

2020: “moderately above average season” > A pretty poor season overall.

This year I am going to stop doing specific Spencer Creek snow depth predictions on a plus and minus basis as I have done previously. It is clear that this is taken into account too many biased factors and makes for poor analysis.

Pacific Decadal Oscillation

We have a classic negative PDO pattern forecast by EC:

This slightly increases snow favourability for the Australian Alps.

Madden-Julian Oscillation (MJO)

The MJO is notoriously hard to predict on a long-term basis, but there is some tools we can use to help predict the rough location of the tropical forcing on a seasonal scale. The warmest SSTAs in the tropical region stretch from the Indian Ocean to Australia, so it is theoretically less likely we will see a strong Phase 6-7-8 MJO signal over winter.

The best period according to the CFS tropical forcing prediction would be in June with a Phase 5-6 MJO. July features weak tropical forcing too far out into the Pacific. And August and September predictions are too far to the west in the Indian Ocean. So the tropical forcing is probably going to provide a neutral impact on us, with an average amount of passes and strength in our region. When they do come, it provides good opportunity for snowfall in the Australian Alps.

Indian Ocean Dipole

We are looking at a cool neutral IOD this season, with only the Meteo-France and Chinese models forecasting a negative IOD pattern during the winter months from last month’s update.

The latest models from this month (less guidance until the other models update) show the Australian, Canadian and ECMWF models more inclined towards a negative IOD.

Below, we see pretty warm sea-surface temperature anomalies in the Eastern Indian Ocean and North of Australia.

These are likely to increase precipitation at least a little bit, in SE Australia. This can bring more snowfall, but it can also be less cold unless it is combined with strong polar cold fronts. A negative IOD is certainly possible in this environment.

El Nino Southern Oscillation (ENSO)

We are seeing the model consensus of the ENSO models in the cool neutral region of the ENSO index. This is arguably quite favourable for us going forward.

The key impact for us is that the Western Pacific is still warmer than normal and is likely to remain so (bar that cool patch off Brisbane), which is likely to increase precipitation. This may assist snowfall in the Australian Alps, but it can also bring down warmth that can bring rain to the mountains during winter. So it can be a double edged sword, but it usually is helpful combined with proper polar nodes.

One of the atmospheric indicators of ENSO, the Southern Oscillation Index (compares sea level pressure between Darwin and Tahiti) is forecast by EC as being Nina-esque (positive values align with a La Nina):

What does this mean for Australian snowfall? Probably a cold neutral/mild Nina effect combining oceanic and atmospheric elements of ENSO, which is pretty good for us.

Volcanoes

If a large stratospheric volcano explosion occurs, Australian snowfall substantially increases for that winter. None have occurred in the last year, so this season won’t be affected.

Sunspots

There is a weak correlation between a higher amount of sunspots and more snow, as found by Francisco Sánchez-Bayo and Ken Green. We are still around the solar minimum, but we are heading out of it. It may have a minor detrimental effect on our snowfall.

Southern Australia/Tasman SSTs

If we look at the two key regions for us, they are basically flipped in our two models here. NMME forecasts a cool neutral SST in the Great Australian Bight, and a warm Tasman, which cancel each other out. EC has a slightly warm Bight, and a slightly warm Tasman, warmer than NMME in the Bight but cooler in the Tasman.

A warm Tasman brings the potential for warmer maritime air to deliver moisture in rain or heavy snow forms. I’d say we will see a neutral Bight, that may get slightly warmer than normal, so a fairly neutral effect on cold fronts. The Tasman will remain relatively warm, but perhaps not as warm as it has been in past seasons.

Southern Annular Mode/Stratosphere

There is a fairly strong correlation between negative SAM and more snowfall for the Alps. I talked about the seasonal prediction of SAM here. El Niño Modoki (a seasonal prediction factor of SAM) is at a neutral phase, and is likely to get slightly cooler towards winter. 

Climate Change as a general trend is causing a more positive SAM. Furthermore on a seasonal scale, the general trend if it continues to hold over this winter is positive SAM-like.

The graphic to the left shows some above average strengthening of the Stratospheric Polar Vortex. The more numerous fluctuations and changes there are, the more interesting it could be for Australian snowfall.

The graphic to the right shows upper stratosphere temperatures above the Southern Hemisphere subtropics. It being colder than average means that more ozone can pass from the NH, and increases the chances for a sudden warming of the stratospheric vortex. This may help troughing and therefore snowfall in our region.

Analogs

Let’s run an experimental analog like my ones done for the Northern Hemisphere. It is common in winter seasonal forecasts in the Northern Hemisphere (especially North America), but relatively rare among winter forecasts in Australia.

The years chosen in the first one are primarily due to their similarity with the warm Maritime Continent and Western Pacific waters, similarity to the Indian Ocean forecast and generally a largely neutral ENSO influence.

The most key feature here is the strong low between South America and NZ. The fact the Australian Alps in SE Australia are between two highs is hopeful, but certainly not definitive.

To try another set of analog years, we will look at just Neutral ENSO winters preceding La Ninas:

And interestingly we see similar patterns to the last one, despite only one year being the same. We see the strong low SW of South America with a corresponding ridge east of New Zealand, some high latitude blocking and some support for roughing in the SE Australia region. This is slightly increased on this.

But if we go even further and control for the Indian Ocean and get rid of +IOD seasons, we get:

We see a very decent troughing pattern for SE Australia under these underlying climatic conditions with these analog years. This may help to increase snowfall in The Australian Alps.

Conclusion

So let’s go through a roll-call of factors into this forecast in terms of impact on Australian snowfall:

  • PDO: Mild benefit
  • MJO: Neutral
  • ENSO: Mild-moderate benefit
  • IOD: Mild-moderate benefit
  • SAM/Strat: Mild benefit
  • Volcanoes: Neutral
  • Sunspots: Negligible benefit
  • Southern Australia/Tasman SSTs: Mild-moderate detriment.
  • Analogs: Mildly-moderately positive for snowfall

So I think it’s fair to call for an average to slightly above average snow season. So around 175-200cm for the Spencer’s Creek snow depth prediction.

Thanks for reading this Australian snow season outlook, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above (through the new link!)

Europe on the long term 14th Jan

Included is a basic overview of the medium-long term modelling, and a deeper analysis into climatic patterns afterwards.

18th-24th Jan

The EC Weeklies have a -NAO block over Greenland, that is reacted to downstream by a trough over Europe, which should help snowfall and cold over the European continent. It should also help bring some cold for the UK from the Arctic. GEFS shows a similar look.

Jan 25th-31st

We see the pattern on EC become more zonal, but the trough is still over Europe, and the -NAO is intact. This should aid cold to continue over the continent, support snowfall in the Alps and Southern Europe, and possibly the UK. Extended GEFS is showing the low further out towards the UK at this stage.


1st-7th Feb

We still see decent potential for the Southern Alps/Europe in terms of snowfall, but the pattern is shifting towards favouring the North. The pattern gets more zonal again and the trough shifts closer to the Atlantic, making it less fruitful for UK snowfall as it gets deeper into mid-Feb. Extended GEFS shows the trough weaker and further out into the Atlantic with a more zonal look.

Climate Drivers

So we have are at the peak of the actual Sudden Stratospheric Warming that has occurred in recent weeks, and we are now seeing the stratospheric polar vortex gain its strength again in the near future. GFS suggests in its long term prognosis in the last few days of Jan into the first week of Feb, that we may see this occur rather fast and in connection to a more positive AO for early Feb:

EC Weeklies (below) show us currently at the peak of the reversal of stratospheric zonal winds, and that we are going to climb rather fast over the next 10 days, that could hint at a more +AO pattern to follow in early Feb.

It means that after the next two weeks, snowfall prospects for the UK and for Southern Europe and the Alps are going to weaken. And eventually as we head into February, it would signal signs of a more zonal +NAO pattern in the Atlantic, that would bring mild conditions to the UK and Southern Europe, but more snowfall for the Northern Alps.

On the other hand, the NAO is forecasted by some long term model ensembles to remain negative as far as March:

So the NAO and AO is a little up in the air, but are possibly heading towards positive as early as the last few days of January, and probably in the first two weeks of February.

The MJO is currently in Phase 3, which when you add a 10 day lag corresponds to a more +NAO outlook (good for snow in the Northern Alps, not so much for Southern Alps/Europe and the UK). Possibly heading towards Phase 6/7 in the first week of February per the GFS projection below, which would correspond to a -NAO with the opposite effect.

The Pacific and global momentum, despite forecast +EAMTs underdelivered, leaving us with a mildly -AAM currently and a medium term period of us being in the Nina-esque base state.

Fortunately for Southern Alps/Europe snowfall and the UK, these GWO phases 1-3 are beneficial for a -NAO bringing cold air down to these places from the Arctic. But the phases 4-6 are correlated with the escalation of a more zonal +NAO pattern, and given the MJO forecast and observed positive frictional torques, it is possible that we see the GWO move into these phases less positive for Southern Europe/UK snowfall in early February. Or we may stay in the negative phases longer term.

Thanks so much for reading. I hoped you enjoyed reading it. 

Disclaimer: There is lower skill asssociated with using long range model forecasts to find snow systems. 

Thanks again for reading this European long range snow forecast, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above.

Japan on the long term 8th Jan

As forecasted in my last long range outlook in December, the last few weeks have turned out great for Japanese snowfall. So let’s see what the climate modelling, and then the drivers have to say about the next month ahead.

24th-29th January

Both GFS and EC Monthly Control are looking at a moderate-heavy snowfall event for Honshu from the 24th, and EC continues it through the 25th and 26th, with more moderate snow driving through to the 29th mostly isolated to Northern Honshu. Light-moderate snowfall begins in Western Hokkaido around the 25th per EC, through to the 29th.

31st Jan-1st Feb

Per EC Monthly, rainfall is brought by a low to Central Honshu on the 31st. Some snowfall in the backend may fall on the morning of the 1st.

6th-9th February

EC Monthly projects a low to head up from the south to bring rainfall for the mountains in Honshu on the 6th-8th, and snowfall on the 8th and 9th to Hokkaido. There is a possibility for a colder backend for snow later on the 8th and 9th for Honshu.

Climate Drivers

The MJO is currently weakly passing into the Indian Ocean, and is expected to move over Australia and SE Asia. Phase 7 MJO (signal over the Pacific) is best for Japanese snowfall, so the MJO isn’t favourable for at least the next fortnight, but only mildly so with a weak signal.

The Arctic Oscillation has been negative since early December on the surface, and this has been brought into the stratosphere with a SSW. So all of that blue signifies a weakening of the polar vortex, which means more cold is sent down from the Arctic. This creates a setup that brings more snowfall for Japan. A negative AO is expected through January, and is favourable for Japanese snowfall.

The duration of the impacts of the stratospheric warming will have an impact on the duration of the favourable cold and snowfall impacts of the -AO.

However at least according to GFS, we are going to see that base state that has brought Japan so much snowfall over the past few weeks start to weaken:

The Siberian High has been very strong through much of December until this point, delivering very cold masses of air to Honshu and Hokkaido creating the lake effect snowfall that has been so prevalent lately.

Hokkaido also received snowfall from strong Kamchatka/Aleutian lows passing through the region, bringing benefits there. Together the strong Aleutian low and Siberian High helped bring the SSW into action and a +EAMT, which limits lows from the south, and locks into cold snow bearing setups from the north.

GFS is forecasting that these mechanisms are weakening. So this snowfall boom is likely to taper off in the last week of January, or possibly the first few days of February (rather similar to what EC Monthly is indicating). But it’s unlikely to be the very end, more like it is just getting turned down a fair bit.

GEFS is indicating a -EAMT state from the 20th of Jan, after a brief back to back -EAMT and +EAMT events in the next week. So from the week succeeding that, the pattern will start to shift to a less favourable one. So basically, enjoy the snowfall while it lasts…

Thanks so much for reading.

Disclaimer: There is low skill asssociated with using long range model forecasts to find snow systems.

Thanks again for reading this Japanese long range snow forecast, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above.

North American on the long term 30th Dec

A deep dive into the climatic drivers heading into the New Year for North America.

  • So among the takeaways from the latest EC Weeklies, we have the proliferation of a strong -NAO, as one can see from the consistent ridging from this week. We also see a largely -AO setup for the next month and a half according to the model.
  • The Aleutian Low gets strong, like really strong, over the next two-three weeks, before winding back up in the way of ridging in the North Pacific into February.
  • The first 10 days of the forecast looks very nice for the Western US, particularly the PNW.
  • As we move into the latter 2-3 weeks of January, we see a period of favourability for the Eastern and Southern US in terms of cold and snowfall.
  • EC contends that troughing in early February will retrograde back towards the West, possibly setting up a good period for them in that early-mid Feb period.

Now there’s two reasons for the really good forecast for Eastern and Southern North America for January for snowfall.

Stratosphere/Polar

We are seeing the beginning of an Sudden Stratospheric Warming, which means that the temperatures in the stratosphere or the upper levels of the atmosphere are warming up, and the polar vortex is disturbed and stops moving in a predictable elliptical fashion. This has the usual effect of bringing a weaker polar vortex at the surface, also known as a negative Arctic Oscillation.

EC Weeklies (above) argues that one is about to occur (a proper reversal of the 10mb zonal wind at 60hPa), there is also growing evidence for it on GEFS and CFS, otherwise showing at the very least a very strong hit at the polar vortex.

We see this in the chart below, as the upper levels become more negative or blue, but we are certainly helped out by the fact that blocking has already started to develop in the high latitudes (NH polar region), and pushed the lows down to the continents.

This sets up the possibility for an exciting forecast for snowfall and cold to be brought to the Eastern and Southern United States, as they are traditionally the regions of North America that benefit from the negative AO. An SSW (or a moderate-major stratospheric disturbance) in this case is brought about by Ural blocking contributing to a positive East Asian Mountain Torque (more about that in a minute) and a strong Aleutian low downstream. This Ural blocking pushes back towards Greenland, as the Aleutian low matures, and helps lock in a trough over the Eastern US (known as a -NAO).

The one potential problem here to watch out for is where the stratospheric polar vortex lands, as the SSW progresses. For the cold and snowfall to follow the disturbed vortex for the East and the South , it needs to be over the North American side of the Northern Hemisphere.

Pacific

The other major factor in the mix here is the growing potential setup in the Pacific. We are potentially going to see a:

  • Strong, possibly record-breaking East Asian Mountain Torque develop over this week, and possibly proliferate deeper into mid-January. This helps to add momentum to the global circulation.
  • A very strong (again possibly record-breaking) Aleutian low and strong North Pacific jet stream.

This is quite possibly the best possible circumstance for one to be in to help bring about snowfall. This often sets up a chain reaction with a -EPO/+PNA ridge push against the expanded Aleutian low to try and achieve equilibrium, which then evokes a trough downstream in the Central and Eastern thirds of North America.

Initially the expanded North Pacific jet should help the Western US for the first 10 days of the new year with some snowfall. But as we start to see synoptic responses to that, we start to see ridging develop over the West Coast, in favour of cold and snowfall on the East Coast.


We are looking at a potentially good period in terms of snowfall risk for the Eastern and Southern US from approximately the 10th of Jan, maybe a little later, peaking towards the latter two weeks of the month, and then continuing into the first week of February, and possibly beyond, but more information is needed for February.

This Pacific setup, if it comes to full fruition, is certainly one of the best I have seen in my years looking at the Northern Hemisphere charts.

Whether it delivers or not, will depend on whether the Atlantic drivers powered by this -NAO/-AO blocking the path across the North Atlantic and the strong Pacific mechanisms that are possibly creating enormous synoptic tension, can work effectively together.

MJO

On that note, we have a fairly neutral MJO (yes I know the RMMs are not great), but it’s pretty conclusive that not a whole lot of driving is happening from the tropics at the current time.

We might see an orbit in the Indian Ocean, that could be a little destructive (for the Eastern US) to the current forecast if it comes to be later in January.

Thanks so much for reading. I hoped you enjoyed reading it. 

Disclaimer: There is low skill asssociated with using long range model forecasts to find snow systems. 

Thanks again for reading this North American long range snow forecast, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above. 

Europe on the long term 20th Dec

Here on the blog we are going to look at some long term modelling and then the climate drivers…

1st-5th Jan

We see an Atlantic ridge present and a strong Ural ridge, with a low in Southern Europe, bringing down cold air over the UK and Southern Europe

6th-10th Jan

We still see the remnants of the Southern European low, but it’s weakening in favour of a European ridge downstream from the Atlantic high. We also see a strong polar vortex develop from the north.


11th-15th Jan

We see a strong Scandinavian low drive mild and wet conditions for the UK and Northern Europe. On the opposite, we see a ridge develop over the European continent weakening snowfall over the Alps.

16th-20th Jan

We see a mild outlook for the UK and Scandinavia driven by a +NAO/+AO. The rest of the continent is occupied by a strong ridge leaving dry conditions.

21st-25th Jan

We see a +NAO driven outlook for a mild UK again, and ridging growing over Europe.

26th-30th Jan

We see the same, a mild +NAO driven outlook for the UK and a ridge for the rest of the continent.

Climate Drivers

To buck the trend of the modelling above, a colder and snowier outlook for the UK and the Southern Alps/Europe seems to have arrived on the climate driver beat.

A sudden stratospheric warming is a strong weakening of the polar vortex in the stratosphere, which enables a negative Arctic Oscillation that helps to bring snowfall and cold for the UK and Southern Europe/Alps.

The chart above shows the extraordinary displacement of the polar vortex that is likely to help bring forth colder effects for Europe and bring a snowier outlook for the first 3-4 weeks of the new year of 2021 for Europe and the UK.

  • From now to the 27th, we expect a -EAMT to come and weaken the North Pacific jet, that helps to push around the NH climate circulation a more +NAO look.
  • Then we see a push towards a more -AO and the weakening of the stratospheric polar vortex with a strong +EAMT from the 27th to at least the 4th of January. This should combine with the stratospheric disturbance for a -NAO and -AO look from the 2nd and 3rd weeks of January as it comes around from the North Pacific.

For now the MJO is neutral for the next few weeks, so won’t affect the weather over Europe much.

But it is clear from the prognosis for the negative AO and the weakening of the stratospheric polar vortex, as well as the recent and future bouts of +EAMTs keeping the AAM relatively high, we may see some cold and snowfall for much of Europe in the first three weeks of January, particularly of interest for the UK and Southern Europe/Alps.

Thanks so much for reading. I hoped you enjoyed reading it. 

Disclaimer: There is lower skill asssociated with using long range model forecasts to find snow systems. 

Thanks again for reading this European long range snow forecast, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above.

Japan on the long term 13th December

Welcome to our first long term forecast for Japan this season.

25th-29th December

GFS is looking at moderate-heavy snowfall for Honshu and Western Hokkaido from the morning of Boxing Day, through to at least the 29th of Jan. EPS Control shows rain from a southern low on Christmas, and then moderate-heavy snowfall for the same areas on the 26th. These falls lighten to showers on the 27th and 28th.

2nd January

Looking like a quick one over just one day on EC Monthly, wet first up for Central Honshu and moderate-heavy snow later from the NW. Snowfall for Northern Honshu and Southern Hokkaido as well throughout.

3rd to 5th January

Nice and cold starting on the afternoon of the 3rd, lasting moderate-heavy snowfall for Central & North Honshu and Western Hokkaido over the 4th and 5th, contracting north on the morning of the 6th, before ending. So 2-3 days of solid snowfall for Honshu, and some for Hokkaido as well.

7th January

Another low from the south, just far enough south to have some cold on the northern flank for some wet snowfall. But still marginal here on EC Monthly

8th-9th January

A day of snowfall from the afternoon of the 8th to the morning of the 9th, with moderate-heavy snowfall for Honshu, with most of Hokkaido largely left out.

Climate Drivers

We are likely to see a weak Phase 6-7-8 MJO influence on the climatic pattern. This may bring a mild positive influence on Japanese snowfall.

The Arctic Oscillation is also looking desirable for Japanese snowfall…

Yes, I say Eastern US and Europe, but the same logic applies to Japanese snowfall, giving us good chances over the next few weeks. This period of negative AO could possibly end in the last week of December, leaving us with a far less favourable outlook in the New Year.

A key factor here is the distribution of momentum in the atmosphere, specifically from the East Asian Mountain Torque:

  • 13th-19th Dec, +EAMT produces conditions conducive for Japanese snowfall.
  • 20th-26th Dec, -EAMT produces conditions less conducive for Japanese snowfall.
  • 27th-31st Dec, beyond perhaps, +EAMT comes back and helps re-calibrate Japanese snowfall prospects again.

It also looks like the Aleutian low will strengthen later in the month, and same for the Siberian High, both helpful for Japanese snowfall:

I can definitely see good snowfall prospects for the last days of the year, and the first week of January. We will have to wait and see beyond that. But looking good overall.

Thanks so much for reading.

Disclaimer: There is low skill asssociated with using long range model forecasts to find snow systems.

Thanks again for reading this Japanese long range snow forecast, follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above.

North America Winter Outlook 2020-21

Welcome to my North American outlook, discussing the models and drivers to come to conclusions about the winter ahead. Discussion is reasonably technical, so if one wishes just to see the results scroll to the bottom.

Seasonal models

This outlook is to be driven by the climate drivers, rather than modelling, but we will give it a look for a point of comparison.

The ECMWF model shows for the Jan-Feb-Mar period, troughing over Alaska and over the Northwestern US, as well as ridging over the East Coast and the SW. This would bring the best snowfall for the PNW and the Northern Rockies.

Sunspots

SILSO data/image, Royal Observatory of Belgium, Brussels

Same as the last few outlooks, basically we are still in a solar minimum, which in theory helps a negative Arctic Oscillation. This would therefore assist snowfall in Eastern North America, but I don’t weigh sunspots highly as a tool in winter seasonal prediction.

QBO

We are looking at a descending positive/westerly QBO, that tends to have an effect at avoiding stratospheric warmings. And as we can see a certain effect on the North American climate:

The general effects shown by the analog on the right:

  • Greenland ridge and Atlantic ridge wedge Canadian trough from the east.
  • QBO driven Aleutian ridge concurs with the ENSO prognosis.
  • Warm and ridge-driven in the south, particularly in the SW.
  • More active and cold in the north, the most in New England and the Midwest.

Our specific ENSO and QBO analog shows:

  • A positive Arctic Oscillation, shown by the trough.
  • Weak troughing for the Eastern US and parts of Western Canada
  • Same Aleutian ridge, with a mild ridge in the SW.

So not great for snow in the Southwest, but potentially hopeful for the Northern US especially on the eastern side of the continent.

ENSO

We are heading into a Moderate Nina for this winter, with us expected to be at the depths of this Nina in the next month or so.

We are in the midst of an east-based La Niña that is stretching throughout the ENSO basin, but still focused on the Eastern end of the Pacific.

Our humble moderate Nina (east-based to basinwide) analog shows:

  • Aleutian ridge pushing more towards the Gulf of Alaska and to the West Coast.
  • Canadian trough, driving cold and snow for Canada and the Northern US.
  • A mild SE CONUS ridge.
  • Less precipitation/snowfall for California and parts of the Southern US.

Stratosphere

I see an average to slightly above average chance for a SSW, most likely in January:

  1. A descending westerly or positive QBO will weaken chances for the development of Sudden Stratospheric Warming events.
  2. Brewer Dobson Circulation is stronger than normal in both of the NH and SH subtropics as well as over the tropics this month. I expect a stronger than normal BDC over the winter. This increases ozone in the SPV during the winter, which increases the chance of a SSW.
  3. Average Siberian Snow Cover does not really affect the stratosphere, but the low Barents-Kara Sea Ice does improve chances for a SSW.
  4. Solar minimum is still taking place at this point, favouring a -AO and potential stratospheric disruption.
  5. December’s +EAMTs and amplified pattern could help to amplify a stratospheric disruption down the road.

Taking a look at the modelling for the stratosphere this season, January looks like the most interesting month for potential stratospheric disruptions on both EC and UKMO, with EC the more enthusiastic option.

These processes if a SSW is successful and is able to propagate from the stratosphere to the troposphere, would be able to assist roughing and snowfall on the Eastern side of the North American continent.

Sea Ice

The NASA GMAO forecast for around Christmas is for lower than average sea ice in the Barents-Kara Sea Ice region, which is more likely to induce a -AO/-NAO and to help to disturb the stratospheric vortex. This would help snowfall/troughing in the Eastern US.

Snow Cover

October in terms of the expansion of the Siberian snow cover was pretty average with a pretty neutral impact. Late October and Early November brought a slump of the expansion, which may have had a negative impact down the line on the potential extratropical cooling effect and setting up of SSWs.

November saw a large increase of snowfall extent across Eurasia, and the resulting impact of that has been the strengthening of the Siberian High. This helps to increase pressure on the stratospheric polar vortex.

Although October wasn’t very exciting in Siberia, November shows some hope for a colder winter for the Eastern US, with potentially a more -AO/-NAO outlook focused on the potential for a SSW.

MJO


Here we have the expected tropical wave pattern for the winter ahead, that focuses on a Phase 2-3 (Dec) to phase 4/5/6 (Feb) approach to the winter, with a slow shift of focus from the Eastern Indian Ocean as the focus of tropical activity, to the Maritime Continent region (North of Australia).

This may assist Western US troughing in the Phases 2-4 of the MJO. We want to see MJO Phases 7-8-1 for snowfall and cold correlation in the Eastern US.

Late October/November have featured a far more positive AAM/amplified pattern, which makes things more interesting with the potential for SSWs and disruption to the polar vortex.

It has also delivered good results in terms of cold for the Eastern/Southern US this month, which could prove more fruitful if it continues.

North Pacific

This is the January North Pacific SSTA forecast, and is possibly quite decent for the Eastern US (and less so for the West Coast). We see that strong warm anomaly off the coast of the PNW, which could help to anchor a ridge closer to the CONUS than the Aleutians, which would have positive impacts for the Central and Eastern US for cold and snowfall.

We also have a warm SSTA setup from 10N and north, and tight anomaly bars/warm waters coming off Japan, which as part of a +PMM helps to drive the North Pacific jetstream. This may provide some help to California, in what is likely to be a lacking winter, and have positive downstream effects for cold/snowfall for the East.

Conclusions

  1. We see an average season for the PNW/BC in terms of snowfall, including into the Northern Rockies (MT, ID, WY). It could possibly be better inland over the Rockies than over the coast, if a Gulf of Alaska ridge pushes in like above.
  2. We see an average winter for Utah.
  3. We see an average to slightly above average snow season for Colorado.
  4. We see a below average season for the Sierra Nevada (CA).
  5. A strong snowfall season for the Midwest.
  6. An above average winter season for New England.
  7. An average to slightly above average snowfall season for the Mid Atlantic to NYC.
  8. An average snowfall season for the Southern half of the US, better the further north one gets.

Thanks so much for reading. Long term forecasts on a sub-seasonal scale for snowfall coming very soon!

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. 

I appreciate all for reading, please follow me on Twitter @longrangesnow and subscribe to my email list by clicking on the tab on the main header above

European Winter Outlook 2020-21

Hello, I am going to analyse the key climate drivers and derive a forecast for the European meterological winter that has just arrived.

Model Outlook

This isn’t going to weigh heavily in the final analysis, but for reference here is the multi model ensemble provided by Copernicus.

For Europe, we see ridging dominating, reducing snowfall for much of the continent. And we also see a +NAO more Atlantic driven forecast for the season in the UK.

Sunspots

SILSO data/image, Royal Observatory of Belgium, Brussels

Same as the last few outlooks, basically we are still in a solar minimum, which in theory helps a negative Arctic Oscillation. This would therefore assist snowfall in Southern Europe and the UK, but I don’t weigh sunspots highly as a tool in winter seasonal prediction.

QBO

We are looking at a descending positive/westerly QBO, that tends to have an effect at avoiding stratospheric warmings. And as we can see a certain effect on the European climate:

The general effects shown by the analog on the right:

  • Greenland high and Atlantic trough, and therefore a rough -NAO setup in the Atlantic.
  • But this has left in its wake a European ridge.
  • This may bring an active Atlantic for the UK, possibly some cold spells, but largely a maritime influence.
  • And of course warmer and drier for much of Europe, the best falls for the Alps based on this towards the West.

Our specific ENSO and QBO analog shows:

  • +NAO and a positive Arctic Oscillation
  • Dry and warm for much of Central and Southern Europe.
  • Possibly wet for the UK.

So overall not very good for snowfall for either the UK or Europe.

ENSO

We are heading into a Moderate Nina for this winter, with us expected to be at the depths of this Nina in the next month or so.

We are in the midst of an east-based La Niña that is stretching throughout the ENSO basin, but still focused on the Eastern end of the Pacific.

Our humble moderate Nina (east-based to basinwide) analog shows:

  • Scandinavian/Barents-Kara ridging dominance.
  • A mild-moderate ridge pattern for SE Europe.
  • A sort of -NAO set-up with Azores troughing
  • Less precipitation/snowfall for Turkey.
  • More snowfall for Southern Alps
  • Less Precip for UK/Northern Alps/Northern Europe.
  • Colder for Eastern Europe.

Stratosphere

I see an average to slightly above average chance for a SSW, most likely in January:

  1. A descending westerly or positive QBO will weaken chances for the development of Sudden Stratospheric Warming events.
  2. Brewer Dobson Circulation is stronger than normal in both of the NH and SH subtropics as well as over the tropics this month. I expect a stronger than normal BDC over the winter. This increases ozone in the SPV during the winter, which increases the chance of a SSW.
  3. Average Siberian Snow Cover does not really affect the stratosphere, but the low Barents-Kara Sea Ice does improve chances for a SSW.
  4. Solar minimum is still taking place at this point, favouring a -AO and potential stratospheric disruption.
  5. December’s +EAMTs and amplified pattern could help to amplify a stratospheric disruption down the road.

Taking a look at the modelling for the stratosphere this season, January looks like the most interesting month for potential stratospheric disruptions on both EC and UKMO, with EC the more enthusiastic option.

Sea Ice

The NASA GMAO forecast for around Christmas is for lower than average sea ice in the Barents-Kara Sea Ice region, which is more likely to induce a -AO/-NAO and to help to disturb the stratospheric vortex.

Snow Cover

October in terms of the expansion of the Siberian snow cover was pretty average with a pretty neutral impact. Late October and Early November brought a slump of the expansion, which may have had a negative impact down the line on the potential extratropical cooling effect and setting up of SSWs.

November saw a large increase of snowfall extent across Eurasia, and the resulting impact of that has been the strengthening of the Siberian High. This helps to increase pressure on the stratospheric polar vortex.

Although October wasn’t very exciting in Siberia, November shows some hope for a colder winter for the UK and Southern Europe/Alps, with potentially a more -AO/-NAO outlook focused on the potential for a SSW.

MJO


Here we have the expected tropical wave pattern for the winter ahead, that focuses on a Phase 2-3 (Dec) to phase 4/5/6 (Feb) approach to the winter, with a slow shift of focus from the Eastern Indian Ocean as the focus of tropical activity, to the Maritime Continent.

Phase 3 MJO + 10 days promotes a +NAO (good for Northern Alps snowfall, bad for Southern Alps/Europe and UK) and Phase 6 MJO + 10 days promotes a -NAO (basically the reverse). So we see a stronger favouring of –

Late October/November have featured a far more positive AAM/amplified pattern, which makes things more interesting with the potential for SSWs and disruption to the polar vortex.

It has also delivered good results for snowfall for the UK and the Southern Alps in the short-medium term, which could prove good if it continues.

Atlantic

This is probably a setup that favours a +NAO in the North Atlantic, with cold SSTAs south of Greenland amplifying a trough, and tight temperature bars from the North American continent that helps to amplify the North Atlantic jetstream.

On the other hand, colder SSTs west of the British Isles may help bring a colder outlook for the UK and the continent at large.

Conclusions

Call it the optimist in me, but this current December amplification event has got me more interested in a colder winter for Europe. The GWO has made it clear that it is at least for December more interested in the potential to see a counter to the oceanic Nina state.

It is important to make it clear that just because we have a Nina in the oceans, this does not necessarily have to translate to the atmosphere.

Given the first half of December is quite possibly going to be focused on a -NAO with positive effects for the UK and Southern Europe, we could see a counter to this over Christmas and New Years.

But I am interested in the prospect of a SSW later in the winter probably in January with its impacts felt in February. So perhaps a more +NAO look moving into January, and another change up possible if the impacts of the SSW propagate to the troposphere.

But these conflicting conditions have certainly made this one a hard for me, and I personally am feeling greatly confident. On the other hand, I have again produced a vague map showing my basic thoughts for this winter.

  • For the UK, an average to slightly above average snow season focused in a colder December and February. A less favourable more maritime pattern in January, with a +NAO, a weaker winter if it remains in control.
  • Southern Alps to get an average to slightly above average season.
  • Northern Alps to receive an average to slightly above average season, focused towards the middle of winter.
  • Eastern Europe is likely to receive average to below average snowfall, but a strong proliferation of the -NAO due to the +AAM or a possible SSW may help out particularly in the SE.

I know that a number of the drivers, particularly QBO and the Atlantic opposes this look. But the potential fluidity of the tropical and extratropical state and possibility for stratospheric disruption shows me at least that it won’t be a entirely awful season for Europe. Whether it bears much fruit is only for time to tell.

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 was a complex one, so I appreciate the support for the blog!

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Japanese Winter Outlook 2020-21

Hello all, welcome to my seasonal outlook for the Japanese snowfall season for the coming winter. Apologies for the later timing this year.

Climate Models

Per the blend of mainly European models (plus CFS) we see here for the NH winter, it is likely that we will see a much weaker than normal Aleutian low, and the possibility of Aleutian ridging. This is not a good sign for Hokkaido, that often relies on snow generated from Kamchatka lows.

The Siberian High looks like it will be weaker than normal at least on it’s northern side, with a positive AO outlook marked by high latitude troughs.

And finally unfortunately we see convection heading towards Japan from the Maritime Continent region, that has negative impacts on Japanese snowfall, increasing the likelihood of rainfall events.

Taking a look at two individual models, first CFS, we see similar patterns. We see the Aleutian ridging, and waning impact of the Aleutian low. We see more troughing than normal and a weaker Siberian High forecast north of Japan. You still see the NWly winds, but the deep cold impact of them would certainly be weakened by it.

With ECMWF model now, you see the same modelling. A strong level of support for Aleutian ridging, more troughing over Siberia (weaker Siberian High) and convection directly south of Japan. Not looking like good news from the models at all.

Sea Surface Temperatures

There are some necessary points to make here:

  1. The warm SSTAs surrounding Japan demonstrate the potential for more ridging around Japan for winter.
  2. The warm SSTAs in the Sea of Japan specifically allow a larger divide between warm sea surface temperatures and cold air aloft coming from Siberia. This could possibly increase lake/sea effect snowfall in terms of strength and duration of events.
  3. But on the other hand, more warmth in the atmosphere is not necessarily a good thing for snowfall either, and may lead to more rain, or less dry snowfall conditions (wetter snow).

Siberian High

“The Siberian High is an important, yet relatively unknown driver for snowfall in the Japanese Alps. A strong, stable Siberian High provides very cold air down towards Japan, except if the High is too far west. This cold air from the Siberian High creates the lake effect, that provides the massive snowfalls in the Japanese Alps.

Snowy Hibbo two years ago

The Siberian High is affected by a number of things, including snow cover in the region and the AO. A negative AO causes a stronger Siberian High. The Siberian High is also affected by the snow cover in Siberia during October and November. An above average Siberian snow cover creates an early, potentially more stable Siberian High. It also correlates with a negative AO.

Snowy Hibbo two years ago

The rise of the snow extent in Siberia was relatively average throughout October, if perhaps a little bit weak. However we saw a strong backoff in early November leading to below average snow extent for that time of year. In the past week or so, the snow extent in Eurasia has expanded rapidly and we have returned to average. We are likely to see a mildly negative impact on the development of the Siberian High, and a negative impact on Japanese snowfall.

ENSO

In terms of ENSO impacts on Japanese snowfall, we are going to use this analog that I made in October (1985, 1989, 1996, 2000, 2001, 2008, 2011, 2018). We are looking at a basin wide/EP La Nina event, as one can see with this ENSO anomalies chart showing current conditions:

So we see certain patterns develop on this chart, that are not necessarily that bad:

  • A stronger than average Siberian High, particularly on the western side.
  • A decent Kamchatka low, playing off a North Pacific ridge pushed towards Alaska.
  • A strong tropical signal south of Japan.

So it is likely that this would mean a pretty decent season for Hokkaido and Northern Honshu, but we will possibly see more wet and warm lows come from the south and negatively impact ski fields in Central Honshu.

MJO

It is clear that the MJO will favour Phases 3-4-5 over the winter, which is not so good for Japanese snowfall with the possibility for more rain from the south. The best phase of the MJO for Japan is deeper into the Pacific at about Phase 7.

Arctic Oscillation

  1. Siberian Snow Cover during the months prior to winter is average to below average, so a +AO is mildly more probable, which does not Japanese snowfall.
  2. Arctic sea ice is lower than average, which helps to angle us towards a more -AO outlook, in particular low sea ice in the Barents-Kara Sea. This would be more beneficial to Japanese snowfall.
  3. The QBO is expected to have an effect of promoting a positive AO.
  4. The stratospheric polar vortex is stronger than normal at the moment, and is expected to stay like that into December and possibly beyond (linked with a +AO)

Because of the above factors, I expect a positive Arctic Oscillation to be dominant, not to say that a -AO is impossible at some stage though.

Conclusions

My basic contention for the Japanese snowfall season is that:

  • Hokkaido/Northern Honshu should expect an average season, perhaps mildly below average.
  • Central Honshu should expect a below average season with the probability of more rainfall events (but not necessarily a complete weakening in the snowfall mechanism)

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 might be like. 

We should see the final winter outlooks for Europe and North America come out within the fortnight.

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

October Preliminary 2020-21 Winter Outlook

Welcome to another winter outlook update for the Northern Hemisphere, including Europe, North America and Japan. For those who prefer a simple reading/conclusion and prefer not to read the long technical analysis, scroll to the Conclusions section at the bottom.

Model Outlook

December actually shows a more -NAO-like pattern on the ECMWF model, which is shown by significant blocking around Greenland, which benefits the UK and Southern Europe in terms of more cold. We also see a strong Aleutian ridge develop, which aligns with the Nina pattern and benefits the Rockies and the PNW. With a weaker Siberian High and Aleutian Low, the Japanese snow seasons suffers.

In January, we start to see a more +NAO outlook take hold in the Atlantic, which brings European ridging and less snowfall for the continent. Troughing over British Columbia benefits snowfall over the PNW and of course BC. Ridging weakens snowfall across the rest of the North American continent, leading to a dry month. Again persistent ridging over Japan weakens snowfall there too.

February brings a clear +NAO with a Greenland low and Azores High, leading to mild and wet conditions for Western Europe, and dry conditions for Eastern Europe. Ridging shifts slightly north, but persists over Japan. Again we see a favouring of snowfall for the PNW/BC at the detriment to the rest of North America.

We see similar scenes on the wider C3S multi-model ensemble for the whole of winter, with a strong Canadian vortex, bringing cold and snowfall over Canada and the Northern US. A strong Aleutian ridge dominates the image, with ridging stretching across America to Europe. We see a +NAO pushing the jet stream into the UK/Northern Europe. And a poor ridged outlook for Japan unfortunately.

ENSO

The current ENSO state is of a Eastern Pacific and perhaps could also be considered pushing into basin wide La Niña, as recently declared by the Australian Bureau of Meteorology.

We know it could be a reasonably strong one and will continue to do so, with the forecast colder than average surface and sub-surface sea temperatures. CFS shows a deep subsurface cold underneath the ocean surface that provides a strong base for this Nina can continue across the ENSO basin.

Following on from that, last discussion I had about this in Early September, I was looking at a Central Pacific Nina. Now I have shifted my personal thoughts have shifted towards a basin wide Nina over winter. Most forecasts show that the emphasis currently upon the Eastern Pacific in the most recent observations will shift towards a more general basin wide look in the coming months, as the Nina progresses (ECMWF as an example below).

So based on the NMME multi-model forecast ensemble, we are looking at a moderate-strong La Niña in terms of looking at the strength of the event:

CFS demonstrates a forecast for a strong Nina, some of the other American models show a weaker Nina and faster recovery.

Putting together an analog for a moderate-strong Nina winters since the 1980s, based in the Eastern Pacific extending into the entire basin:

  • Troughing/low pressure in the Eastern Indian Ocean and over Maritime Continent, certainly goes with the idea of a strong tropical standing wave over Maritime Continent.
  • Strong Aleutian Ridge, supports snowfall and cold in Northern America and Canada. Less North Pacific Jet extensions, less atmospheric rivers.
  • A very weak -NAO and more obvious Scandinavian blocking, which may help support snowfall and cold in Southern Europe/UK.
  • Decent troughing of east of Japan versus strengthened Siberian blocking, which supports Japanese snowfall.

Arctic Sea Ice

Sea-ice in the Arctic is continuing the lower than average trend of the past few decades.

Some analysis of this:

However low sea ice in certain regions is of more importance to us.

NASA GMAO

The sea-ice (NASA GMAO) forecast for the Arctic is pointing to low sea ice in the Barents and Kara Seas, which leads to more blocking in the Arctic region and the proliferation of a more negative AO state that benefits for snowfall, Eastern US, Japan and UK/Southern Europe.

Slightly lower than normal ice coverage out into the Chukchi Sea in that forecast, but mostly a neutral impact from that particular region. It is worthy mentioning that ice in that region is currently very low, so a quick turnaround would be needed to get to a more neutral impact stage. The below map from LDEO shows stronger than normal sea ice in the Bering Sea for DJF (and lower sea ice in the Barents-Kara Sea), and this isn’t an outlook I am really buying, it would be a very strong turnaround of sea ice to get to that stage.

LDEO

Overall I certainly believe we will see a lower than average sea ice year through winter, which in the case of the Barents-Kara Sea, will be a positive influence for higher snowfall and more cold for Europe/UK, the Eastern US and Japan.

Snow cover

We are currently seeing lower than average Siberian snow cover as of midway through the month of October.

Judah Cohen

It is however expected that snowfall will ramp up to some extent in Siberia over the next 10 days, as seen on ECMWF below.

So upon that analysis, I am envisioning a pretty average snow cover by the end of the month, middle of the road, but I may change this prognosis in the formal regional seasonal outlooks once the month has concluded. So it’s impacts are therefore pretty neutral on the climate.

MJO

Here we have the expected tropical wave pattern for the winter ahead, that focuses on a Phase 3 (Dec) to phase 4/5/6 (Feb/March) approach to the winter, with a slow shift of focus from the Eastern Indian Ocean as the focus of tropical activity, to the Western Pacific.

To say the least, these forecasts are not overly great for most seeking out snow.

  • The US West Coast does best after an extension of the North Pacific Jetstream, allowing for atmospheric river events and higher precipitation/snowfall on the mountains. This is best done with a Phase 7/8 MJO.
  • The Eastern US receives it’s best snowfall during the MJO Phases 8/1.
  • Phase 3 + 10 days promotes a +NAO (good for Northern Alps snowfall, bad for Southern Alps/Europe and UK) and Phase 6 + 10 days promotes a -NAO (basically the reverse).
  • Japan receives the most snowfall (by the strengthening of the East Asian Winter Monsoon) around Phase 7.

Either way, the MJO’s impacts are to be unhelpful for snowfall prospects earlier in winter, and more helpful later in winter, as more westerly bursts enter the Pacific.

Sunspots

SILSO data/image, Royal Observatory of Belgium, Brussels

Same as last outlook, basically we are still in a solar minimum, which in theory helps a negative Arctic Oscillation. This would therefore assist snowfall in the Eastern US, Europe and Japan, but I don’t weigh sunspots highly as a tool in winter seasonal prediction.

QBO

The westerly/positive QBO has popped back into the seasonal outlook, after a rather malformed easterly QBO phase this year.

This is of benefit to a +AO/+NAO state, and therefore snowfall in the Western and Central US. And of less help to Europe, the UK, Eastern US and Japan, in terms of producing cold and above average snowfall (less weakening of the SPV and less correlation with a -AO).

The easterly phase on top at 10mb is present, but it won’t descend far enough to be of importance to us this winter. More information pertaining to the dynamics of the QBO is in this below quote from last year’s outlook (obviously technical):

“However it gives the false impression that the QBO is this one number index, which isn’t what it really is. It really is an Oscillation that goes from 5-10mb all the way down to 90-100mb within the equatorial region in the stratosphere, bounded by more anomalies associated with ground conditions and the Hadley cells below, and the Semi Annual Oscillation (SAO) above it. This means when the QBO is positive and descending at 30mb, it may for example be negative zonal wind anomalies below 50mb to 100mb. This shows that the effects of the QBO are not strictly linear, because of this inconsistency within the same Oscillation, creating different effects depending on the height and phase of the descending QBO. There is also the strength of the QBO to contend with, and whether the trend is for a normal QBO phase progression, or a sudden change in progression. These are all factors which play into the QBO’s effect polewardly towards the Stratospheric Polar Vortex, therefore on it’s tropospheric counterpart and then the general hemispheric circulation”

If you wanted to pick the ENSO analogs above that best fit the current QBO progression, you get this:

Obviously looks good for Northern US and Canada and even over much of Europe with a -NAO setup. Too much troughing in the East Asian region for better than average snowfall for Japan.

Stratosphere Polar Vortex

Looking at the extended range forecasts for the stratosphere, we are looking at a pretty average and normal beginning to the rise of the SPV.

EC starts with the stratospheric vortex weaker, but largely charts a pretty average course.

The bias-corrected CFS model, charts a similar course if a little weaker than the average increase through November and December. So a pretty neutral look through the first parts of the winter from the available modelling.

The only other datapoint we have in relation to SSWs and the stratosphere is to do with the transport of ozone from the SH to the NH.

Tropical upper stratosphere is currently colder than average, that indicates a stronger than normal Brewer-Dobson circulation, pushing ozone towards the NH Strat polar vortex. So again we certainly have the capacity for inducing a SSW, it’s just whether the tropospheric factors allow for it.

Another analog for the ENSO years discussed above, this time for the SPV:

So interestingly we see a capacity for the creation of SSWs in the month of February under these years, so something worth thinking about.

North Pacific

We see a very warm North Pacific. This certainly may help with precipitation a bit for the West Coast, with the Nina not helping in this aspect. But it also means ridging in the middle of the North Pacific, helping to reinforce the Nina-esque Aleutian High. So basically reinforces the focus on the Northern US for snowfall and cold.

North Atlantic

We see a clear contrast between the warm SSTAs south of the line between Newfoundland and the Iberian Peninsula, and the cool SSTAs south of Greenland. One will find the jet-stream develop along this line. The cool SSTAs south of Greenland will help to induce troughing over Greenland, or cause a +NAO setup with a strong North Atlantic jet stream. This correlates with a milder outlook for the British Isles, more snow for the Western/Northern Alps and less for the Southern Alps.

Conclusions

To summarise the factors discussed:

  • A basinwide moderate (possibly strong) La Nina this winter.
  • A positive QBO
  • Solar Minimum
  • Atlantic SSTs favourable for a +NAO
  • North Pacific SSTs favourable for a Aleutian Ridge.
  • Average growth of Stratospheric Polar Vortex into winter, potential for SSWs later.
  • Phase 3-6 MJO centred tropical base state
  • Low sea ice in Barents-Kara Sea.
  • Average snow coverage in Siberia.

To apply this to the major snowfall regions of the NH:

  1. We see a better than average season for the PNW/BC in terms of snowfall, including into the Northern Rockies (MT, ID, WY)
  2. We see an average or slightly above average winter for Utah and Colorado.
  3. We see a below average season for the Sierra Nevada (CA).
  4. A strong season for the Midwest and Northern US.
  5. A mildly above average season for New England.
  6. An average snowfall season for the Mid Atlantic to NYC.
  7. A below average snowfall season for the Southern half of the US.
  8. Moving onto Europe, we see a colder December for the UK, and a pretty average winter overall, with a weaker backend of the season.
  9. The Northern Alps should see an average season, maybe slightly better than normal.
  10. The Southern Alps (and the rest of Southern Europe) should see a slightly below average season, with the best conditions early in winter.
  11. Honshu and Hokkaido are likely to see a poor snow season this year, the latter half of the season is likely to be the better one. Possibly a bit better relative to the average for Honshu, than Hokkaido.

Thank you for reading this winter outlook! Stay tuned for the individual regional outlooks, where we look these conclusions and details in.