Australia on the long term 12th August

18th-22nd of August

We see a new long wave trough come through the region around this period, which shows potential for snow-bearing cold fronts. We see a proper cold trough come up on the Tuesday and Wednesday next week, as indicated by the cold air seen on the ensembles.

We see it squeezed between a ridge over NZ and the ridge SW of the trough towards Antarctic. This brings a longer trough trailing the main cold node, which brings a westerly theme to this particular system.

GEFS has a very similar setup, featuring all the same key components, with a slightly enlarged upper level cold node.

GEPS shows a zonal pattern from the Indian Ocean, with troughing anomalies stretching from WA to SE Australia, with the cold node nonetheless centred on the Southeast

Zooming in on the deterministic point of view, we have ECMWF here:

As one can see the front comes over SE Australia early on Tuesday, and pushes through to the Alps during the day.

We see stronger snowfalls associated with the cold airmass on Wednesday afternoon into Thursday morning. Then we see the main node push into the Tasman on Thursday, but we see a backdoor low coming up from the south during Thursday night into Friday, pushing up into NSW throughout Friday and bringing snow to low levels further north.

GFS shows a similar system coming down from the West on the Tues/Weds, and collapsing into the Tasman as a large-scale cold air mass. We then see the polarisation of a sharp deep low coming from the south, similar in timing to EC on Thursday night into Friday, but stronger, colder and it doesn’t shift as far north as EC.

So overall we have a great opportunity here, looking like a 30-50cm system at the moment, even more is possible with that follow-up low from the back. Certainly looks like a more traditional system, compared to some of the Tasman-based systems of recent.

Further systems

Looks like we will have potential for another cold and snow-bearing system around the 27th August to the 31st of August, per the rotation of the Long Wave Trough.

Beyond that, perhaps a possibility for a system around the 4th-9th of September, EC Monthly is willing to play ball with it.

EC Monthly is showing a stronger signal for the 17th-23rd of September as well for a cold front through SE Australia.

MJO

We are currently in the best MJO phases for snowfall (and it hasn’t delivered a lot), but we may see it’s lingering effects on our region with the system next week.

You see the strong phase over Australia/Maritime Continent, and then it weakens and skips the Western Pacific, and strengthens within two weeks over the American continent. This serves to weaken any push away from a La Niña, and generally helps to lean towards a negative AAM state in the next few weeks. This is certainly something that could potentially help our snowfall chances.

Phase 8/1 are certainly highlighted by both EC and GFS ensembles, passing up expansion into the Western Pacific phases, which would spike momentum in the tropics. While the MJO will no longer be favourable in a week or so, the base-state might be improving for us.

AAO

We are currently heading towards a -AAO state for the next week or so.

As you can see the phase is strong, but quite likely to be temporary, with some more +AAO spikes later in the month. But hopefully we can push towards a few more -AAO moments.

Also worth noting that the stratospheric polar vortex in the Antarctic remains largely stable, with only minor disturbances and relative maintenance of strength at the moment.

EC concurs with the GFS model point of view below….

Thanks again for reading this Australian 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.

Australia on the long term 26th July

Apologies for a lack of posts in the past weeks, life has got a little busy at the moment unfortunately. Onto the analysis….

2nd-6th August

The LWT is expected over SE Australia early in August, which means we might see a system off the backend of the larger node. There is plenty of signs that it may peak over SW WA, as has been happening with a number of systems due to stronger westerly (more convection) activity in the Indian Ocean in the past week or so. The tropical signal is forecast to move towards Australia in the first week of August, but it may not come soon enough for us to enjoy the benefits of a SE Australian peaking system.

It also increases the likelihood of a trough across the continent stretching from the SE to the NW of Australia, bringing down tropical moisture.

You can see this clearly on GEFS, but we also have a decent southern trough based off of this, that can bring decent cold and possibly snowfall.

EPS (EC ensembles) show a stronger trough from the south, but it isn’t a very deep cold front, so obviously not going to lead to maximum reward in terms of snowfall. But there is nonetheless some potential for something.

A vague cold front linked to the NW trough is to be found on GEPS, leaving all of the ensembles relatively on the same page, albeit with varying strengths. They have consolidated upon the weakfish cold front feature in the last couple of runs, prior just featuring a vague trough. It is possible it may return to this given a poor +AAO status, but there is certainly still a chance.

Overall not the most exciting setup there is, but there is certainly potential for something there, if all it is would be a clipper with 5-10cms, we will take anything at this point.

10-14th August

If we take the LWT chart at face value, we may see some potential around the LWT peak on the 10th and 11th and in the days succeeding it. But if GFS is anything to go by, it looks to be a Southwest WA peaker as well.

EC Monthly doesn’t like it very much.

20-25th August

If we continue to follow the cards indicated by the GFS LWT, we are lead to this date range.

EC Monthly indicates some activity in the Australian region during this period, and further into the last week of August, that may bring some potential for troughing in the SE of Australia.

Antarctic Oscillation

It looks strongly likely unfortunately that we are heading into a positive phase of the AAO, which is bad for Australian snowfall. As one can see from these charts, it is rather cyclical in nature which gives us some ability to predict it’s manifestations. Based upon this notion, August is likely to be largely a +AAO month, with a more negative outlook in the last third of the month being potential.

It is also important to note that the stratospheric polar vortex at it’s upper extreme here remains strong and cold, so it is unlikely to help us with any real change to the SH atmospheric circulation to help snowfall.

EC is a fan of a strong +AAO event, weakening out chances in that first week of August.

GEFS is forecasted a potential push to a -AAO reprieve from the 10th of August into the mid-month period.

MJO/AAM

On the more positive side of things, the MJO is very possibly moving into our region, at least in some capacity.

You can see the GEFS MJO forecasted tropical wave, move into the Australian region, which is beneficial to us.

Other modelling like that from ECMWF EPS is less hopeful of such a direct incursion into the Australian region, preferring to stay with the pre-existing base state that is leaving us in limbo, benefitting SW WA more than us.

This shift in momentum is leading towards a more positive AAM, as per CFS.

Although the correlation with the AAM on the data is better with a more negative outlook for snowfall, it could also possibly symbolise a little bit of a shake up in the pre-existing base state, which might get us out of this mundane pattern over the past few weeks (particularly in Victoria).

So there is still hope, but yes the numbers are not in our favour with the AAO at the moment, with some potential in the tropics. We shall wait and see.

Thanks again for reading this Australian 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.

Australia on the long term 21st June

Some very intriguing systems and climatic conditions to talk about, which should hopefully bring us more snowfall in the next few weeks!

But I don’t think we can go without acknowledging today’s snowfall for the Snowies, and the good potential for more snowfall over the next few days.

Taken by Charlotte Pass Snow Resort

1st-7th July

Something that was called in our last outlook a little more than 2 weeks back is becoming clearer to see now.

There are a number of schools of thoughts from the modelling about this period:

  • EPS (above) is looking for a peaking trough through the 2nd-4th of July, with this being on trend in terms of timeline from previous runs (albeit it has significantly strengthened in nature since)
  • GEFS (below) delivers us a more muted affair trying to come up over the 4th all the way through to the 7th, not as grand or strong as the EPS effort. This has been on for about two runs, succeeding a less bountiful collapsing trough to clip SE Australia, so the system is improving on trend on GEFS.
  • GEPS (not pictured) offers a more meagre scenario with a break between the ridges during the 3rd to 5th of July, being the less exciting of the models for this period. The Canadian ensemble has bucked the timeline of previous runs, pushing forward from the 1st-3rd July.

EPS is certainly the keen one and certainly has decent trend and reputation to back it. Beyond the modelling solutions, looking at the projected long wave node on GFS:

The LWT is aligned roughly around the 3rd of July. The best systems typically occur just after the long wave node, so it implies that the best possible period of favourability for the SE Australia region would be from the 3rd to the 6th. But as Deterministic GFS has appointed itself upon in the most recent run, we could always have a curtain-raiser just as the node begins to pass.

And the better main system which the first trough has cleared for gets to pass through on the 3rd-7th of July.

EC also has a massive node in the Bight, that is due to land in SE Australia’s doorstep around the 3rd of July. It is yet to be seen if this peaks over SA, or the ridge leans over it and pushes the conveyor belt right into the Australian Alps. It also might be pushed a little later as this system forecast matures, but it’s certainly the stage on what could very well be the season starter for 2020.

10th-14th July

We are looking at another potential system period in a little while, shown by the LWT south of Madagascar that should be in our region around the 10th-14th of July.

EC Monthly Control certainly agrees with a scenario that is set-up to deliver moderate-heavy snowfall for the Australian Alps. It’s certainly potentially a big fish.

20th-24th July

Should we want to go even further with the forecast, I can see the next LWT node in our region around about this time next month.

EC Monthly Control is certainly trying for it.

MJO

We are currently outside of the tropical signal, but by the end of the month and into July, we should see the tropical signal move into our region, which is beneficial for our snowfall, and should really help the 1st-7th July period come to fruition IMO.

AAO

We have a number of conflicting takes from the models on the all important long range forecast of the AAO.

EC shows a great setup for the rest of the month, as we see a strong negative decline, heading towards that potential in the first week of July. However of course it is uncertain how long it will stay like that once in July, but noting the model trend and the gravity of this switch, there is potential for it to be a while.

It’s worth discussing the GEFS, which shows a decline in the AAO now, but struggles to hold that into July. It could be said that it has a bias towards potentially strengthening the Southern Hemisphere polar vortex in the upper stratosphere, but only time will tell, but it certainly doesn’t look amazing.

But it’s American compatriot in the GEOS (NASA model), shows a solution more like EC, and shows a potential for a longer term dip of the -AAO.

AAM/GWO

We see a trend over the month for a positive AAM to grow, which may be bad news come mid-late July, but for the next few weeks we see:

  • A pre-existing negative AAM base state which is good for Australian snowfall.
  • And potential for positive mountain torques that would help to disrupt the stratospheric polar vortex.

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.

Charts courtesy of Tropical Tidbits, Weatherzone, Weathermodels, Accuweather, Michael Ventrice, Stratobserve and Victor Gensini

Image courtesy of Charlotte Pass.

Australia on the long term 5th June

Welcome back to this season’s long term outlooks for the Australian snow season. First we will look at the modelling for dates, and then the climate drivers.

14th-17th June

GEFS and EPS both show a trough peaking over Western Australia and falling down into Southeastern Australia and Tasmania starting either over the 14th and 15th, and pushing through the 16th of June, which may bring little for the Alps, could also be a signal for a warm and wet front, and it also could possibly mean a chance of some snowfall, which has been flirted with by GFS at times.


EPS shows more of a cut-off low scenario, and GEFS has a more trough-based scenario, and both have been slowly improving the prospects with this period.

23rd-27th June

EC Monthly Control shows dual troughs on the 23rd of June and 26th of June, both bringing snowfall to the Australian Alps. The ensemble mean doesn’t really connect with these ideas however, showing primarily ridging during this period.

On the North American model ensemble side, this period is forecast to feature ridging for SE Australia, but shows troughing over Western Australia.

2nd-7th July

You can see the LWT node for the date period above is relatively weak on the chart below south of Madagascar. But there may be something more interesting on the next cycle after that on the 2nd-7th July.

Antarctic Oscillation

The AAO is forecasted to stay positive over the next two weeks for the most part, and it is clear that we are in a positive AAO state of play for a while indeed. The brief more neutral reprieve may be a catalyst for the WA peaking system as it aligns well with this event on the charts.

As for when we will see a more solid negative phase of the AAO, it is looking possible that we will see an easing of the positive state in the 15th-25th June timeline, per EC guidance, but it is very possible the models are showing us a false end to this state as well. But looking relatively good of heading towards a more negative phase in the later stages of the month or possibly in early July. AAO states typically cycle around a month or so, which means these timelines generally go with that flow.

MJO

The tropical base state is looking like it will benefit the Phases 1-3 of the MJO in the Indian Ocean. This is possibly a reason for the consistent progs for a WA peaker pattern for the rest of the month.

For Australian snowfall, we would prefer the negative cool coloured signal to be over Phase 5 and 6 within our region.

There may be a possibility for the MJO to enter our region in the last few days of the month into July, but this is only a possibility at this point.

GWO

As to be expected, the Global Wind Oscillation is largely acting in the mold of the MJO staying around the Phase 1 zone, however also similar to the MJO it is being generally kept in the neutral influence area.

The negative phase around the 13th of June may assist the medium-term system around that time down here, but a general more positive trend would increase the zonal flow in our region, that may serve to get rid of the dominant ridging blocks, but also weakens the chance for cut-off lows that bring good snowfalls.

Disclaimer: There is lower skill associated 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.

Australian Snow Season Outlook 2020

G’day everyone, it’s that time of year. And we have been thrust into the game with a major 50cm+ system over the last few days. We are here today to see if that will continue deeper into the snow season.

So we are going to look in this article about the potential for the season as a whole, using model analysis and climate drivers later on. If you aren’t keen for the technical details, the conclusions are near the bottom.

Verification

My prediction for 2019 at Spencers Creek was 176cm, we actually ended up with 228.8cm as our season highest snow depth. My third year of being outdone by Mother Nature. One may see this is good, but for me, it’s always a sign that more work needs to be done for this forecast to remain as close to the final depth as possible.

One thing I have found is that the arbitrary number is inflexible with the way I weighted climate drivers in the past few years. So you will notice that I will become more liberal than usual with that weighting process. But it is best to consider the final number for what it’s worth, and focus on the climate drivers themselves and the overall vibe of the season as depicted by the outlook. But that said, I will provide a number at the end.

Model analysis

EUROSIPS (including premier European models such as ECMWF and UKMET) paints a troughing picture for Southern Australia, particularly for the latter stages of the season. The troughing tends to favour the WA/SA part of the continent more, but it would lead to improved snowfall outcomes for SE Australia, just perhaps not as much as if that trough centered on the East Coast.

CANSIPS (Canadian model) points to a wet and cold outlook for SE Australia and the Australian Alps. This certainly would be a good sign for us.

CFS (American model) points to troughing peaking in the Bight. That’s not awful for us, there should be some systems that break through to the Alps, but that sort of setup emphasises sliding systems and as CFS forecasts, a wet outlook with prefrontal rains.

JMA (Japanese model) only covers May-June-July, but I am just showing it due to some interest in it’s abilities in the weather community, with it giving us a good outlook for snowfall at least in the early-mid season.

Climate Drivers

Okay, now with the models checked, we can do the traditional climate driver analysis. We will start at 194cm this year, our 10 year average, 8cm higher than last year’s 10 year average of 186cm. This is due to the last three years being consecutively very good seasons, in amongst an otherwise average decade. The use of this number reflects me trying to stay in with the current climate, but of course outliers pose a threat to a small base of years.

Pacific Decadal Oscillation

The PDO is currently negative and while the -SSTAs are weakening off the California coast, the North Pacific warm pool is forecast to stay in place. A negative PDO is forecast for this winter, which increases rainfall prospects for Australia a bit. Hence it increases snowfall chances a bit for us. 194 + 2cm = 196cm

Southern Annular Mode (SAM)

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 (the only seasonal prediction factor of SAM, other than a weaker correlation to Eastern Pacific Nino) is at a neutral phase, and is likely to get cooler towards winter.
  • July and August ECMWF and EUROSIPS modelling show some ridging around the South Pole, which increases the likelihood of a negative SAM, which is good for us, but only just in our favour.
  • Climate Change as a general trend is causing a more positive AAO.
  • The general trend if it continues to hold over this winter is towards a positive SAM.

Overall I think I will go with 196 – 8cm = 188cm, because I am falling towards that general trend. You would hope that there are some negative periods in that trend during the season, otherwise that moisture from the north that I forecast below is likely to fall as rain. The biggest caveat of all, is that there is a fine-line between “cold and moist”, so heavy snow, and “warm and wet”, so heavy rain. This is why the timing of negative SAM events is critical for a good season.

Indian Ocean Dipole/Northern Australia SSTs

This was causing some issues over the summer, contributing to the terrible recent bushfire season, in coordination with climate change. But now we are in better shape for the winter ahead with the IOD.

There is a correlation between the Australian snowfall and the IOD. I am growing more fond of more specific regional SST trends, rather than relying on big global ideas such as the IOD, so of particular note to us is the warm waters north of Australia. These will deliver good moisture to south-east Australia, to help fuel our snow systems. The major models all point to a negative IOD during winter, which is good news for snowfall in the Australian Alps. But keep an eye on the warm waters in the north here, as this is what will decide our fate in terms of moisture.

For here, 188 + 9 = 197cm.

El Nino-Southern Oscillation (ENSO)

There is a correlation between ENSO and Australian snowfall. The current model predictions show a fairly cool neutral state going into winter, perhaps borderline La Nina towards the end of the season. This would make our snowfall season a bit stronger especially towards late season, but the impact is likely to not be strong. What is important here is warm water is pushing towards Australia as part of local trends, so it does look somewhat decent (I do take this into account with the IOD section above).

Atmospheric Angular Momentum (AAM/GWO) (more here) indicator is become more neutral (albeit slowly) after a long period of strong positive cycles. I predict a warm neutral Atmospheric ENSO, and perhaps a weak Nina effect. I will put this in the win column, but only just.

197 + 3 = 200cm

Madden-Julian Oscillation

Australian snowfall and MJO have a very strong correlation. The CFS model shows a signal for Phase 1-2-3, the seasonal signal moving closer to Australia slowly as the season goes on . This is okay if we can get moisture from the Indian Ocean to come across, and at least it means that there is likely to be an active tropical signal throughout the winter.

The weakening in GLAAM/GWO positive cycles (see link in ENSO section for more info) means that the MJO is probably going to lose some of its strength, but I’d be surprised if we went into full-on -AAM cycles until later in the season. MJO tends to be stronger in oceanic La Ninas, particularly building towards a Nino (basically the opposite phase of which we are in).

I think there will be some sort of decent tropical signal, particularly with warm SSTAs in our region, 200 + 3 = 203cm

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 at the solar minimum, so I am going to cut off 2cm

203 – 2 = 201cm

Volcanoes

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

201cm, no change

Southern Australia SSTs

The bight is colder than average (link updates), which is good for Australian snowfall. The Tasman is a little warmer than average. The Bight is forecast by EC to stay cold at least until late-season, where it might start to warm up. CFS and CANSIPS like cold seas surface temperatures throughout the season, which is a good sign. Meanwhile, the Tasman is expected to heat up a bit more, but it’s not going to be crazy warm. Conditions particularly in the GAB are pretty good for the ski season, albeit deteriorating potentially into Spring.

201 + 6 = 207cm

So my final maximum Spencer’s Creek Snow Depth for this year is 207±30cm. This number has came around from hours of analysis, tinkering and changing. The model outlook in the first section of the blog, is roughly in favour of a snowier than average season, though it may come with significant rainfall. The 207cm figure is higher than the 10 year average of 194cm mentioned above. Taking this into account, I am forecasting a moderately better than average snow season for the Australian Alps.

In terms of when the season will be best, the factors seem to be weighing against each other, with the MJO being best earlier in the season IMO, and ENSO and the IOD being “better” later on in the season. I think it will be a pretty typical season, in terms of timing of snowfall, all in all. But as I said above, the AAO/SAM will be critical in determining this season’s fate.

I hope you enjoyed this analysis, and I will see you for a long range outlook before opening weekend. Please share this with skiing or boarding family and friends, I really appreciate all the support.

Thanks again 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.

Europe on the long term 23rd Feb

6th-10th March

Ridging dominates Western Europe, blocking snowfall for the UK and the Alps. The far eastern Alps may do a little bit better. Far Eastern Europe is set to do well in this period with troughing.

11th-15th March

Ridging dominates the European continent, with a +NAO in the Atlantic as a background feature, helping to pave out the Synoptics.

16th-20th March

The +NAO trough strengthens forcing a more zonal setup for the UK, ridging persists for both most of the UK and the Alps.

21st-25th March

The +NAO consolidates and brings zonal conditions for the UK and Scandinavia. Ridging continues over the European Alps.

26th-30th March

The +NAO weakens a bit, and allows ridging to move north back over the UK, while continuing to persist over the Alps.

Climate Drivers

The atmospheric momentum budgets show less positive deposits in the tropics after the spike in January, that had little consequence in terms of changing the pattern. Those tropical deposits are starting to pick up again, because the MJO is making another pass.

The positive deposits between approx 40N-60N and the negative deposits at approx 15N-35N have reestablished, which is essentially a consolidation of the status quo. This means that the strong Atlantic +NAO will continue and the +AO strong vortex state will persist for the next month or so.

The stratosphere is holding firm with a very strong polar vortex state. This means that the Arctic Oscillation is likely to stay positive for quite some time deep into March and probably beyond.

The past 10 days of the MJO being in Phase 6 is behind the somewhat neutralisation of the NAO, which will potentially help bring about decent snowfalls for the UK and the European Alps, as well as the rest of the continent.

After the tropical support has gone away in mid-March, Europe is likely to continue to be subject to bouts of European ridging as predicted by the EC Monthly model above, and to a +NAO base state, fuelled by a strong +AO.

Verification

Here are the predictions that I made in November for the European seasonal outlook:

  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.

Unfortunately it didn’t really pan out this way:

  1. This did pan out okay.
  2. This of course didn’t pan out, the season didn’t improve in the way I forecasted.
  3. Scandinavia had a pretty good season (as far as I can tell using seasonal charts).
  4. The UK didn’t have a good season at all. So this big call did not pay off and was a failure.
  5. The Southern Alps started off well, but a relatively average winter hasn’t really qualified for an above average season overall.
  6. This is probably the best verification for me (the Northern Alps), it was mostly average and a little bit above average in some areas from what I can tell. Lower down, the verification has not been so great, with less snowfall.
  7. This prediction failed, with Eastern Europe having a pretty meagre season.
  8. And this one failed as well with much of the lower Pyrenees doing poorly. The higher slopes are doing about average, but overall not so great.

So overall Europe was milder and more zonal than I had expected, due to the base state failing to budge throughout the season. Limited stratospheric activity and a strong positive AO helped to fuel a poor snow season for much of Europe.

Thanks so much to everyone who has read the blogs throughout the season. I hoped you enjoyed reading them.

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. Enjoy the spring’s worth of skiing, and you will see me again in September and October for next season! I will hopefully see you then.

North America on the long term 16th Feb

4th-8th March

Mild troughing for the Northeast US and the Southern California region. A SE Ridge is persistent in this period, together with a strong +AO and a +NAO. A very strong Aleutian Ridge is in progress as well, per EC Monthly.

9th-13th March

Western US troughing in this period is anchored by a SE Ridge and strong Aleutian ridging, together with a strong +NAO.

14th-18th March

The Western US troughing declines, but the Aleutian ridge and Eastern US ridging are still in place playing into a +NAO-esque Atlantic.

19th-23rd March

Troughing returns to the PNW/BC and the Sierras, again anchored by the Aleutian high and increased Eastern ridging,

24th-28th March

The trend of troughing for the Northwestern US down to Tahoe continues, with the Eastern ridging and Aleutian High still present.

Climate Drivers

The Arctic Oscillation remains in very strong positive territory. This has been assisting snowfall particularly in the Northwestern US, and in British Columbia and Alberta.

The MJO is expected to be briefly within the Phase 7-8 region, which may explain a slight tilt towards the Eastern US in terms of systems, and a slowing down of the snowy pattern for the PNW/BC region. But the +AO will ensure that this will probably not eventuate to much snowfall for the Eastern US. This favourability if you can even call it that, will slow down as we go into March, with the Western US expected to be the big winner of March again.

We see little activity in the stratosphere of consequence that may weaken the strong stratospheric and also tropospheric vortex. GFS notes some hints towards neutrality at the surface, but given the stratospheric base state I would suggest that the +AO theme that has been going on since the start of this year will continue.

The atmospheric momentum budgets show less positive deposits in the tropics after the spike in January, that had little consequence in terms of changing the pattern.

The positive deposits between approx 40N-60N and the negative deposits at approx 15N-35N have reestablished, which is essentially a consolidation of the status quo. A strong Atlantic (+NAO) will continue, the PNW will continue to be favoured in general and the Eastern US will be less favourable for snowfall.

Verification

So this has been a hard year for those involved in seasonal forecasts. Here are the predictions I made:

  1. The Interior of the East Coast on the Appalachians and further west is set to have a better than average snowfall season. The East Coastal regions are set to have a mostly average season.
  2. California is set to have a largely below average season. It won’t be absolutely abysmal though, with potentially improving conditions later in the season.
  3. The Southwest of US is set to have a largely average season, with New Mexico doing better than Arizona.
  4. Utah is set to have an average season. Which tends to be pretty good anyway.
  5. Colorado is set to have a mildly above average snowfall season.
  6. The Canadian/Northern US Rockies are set to have a mildly above average season.
  7. The PNW Coastal mountains are set to have a mildly below average season, but I can see them having a better early-mid season compared to California.
  8. The Central Interior US from the Great Plains to the Midwest to the Tennessee Valley is expected to have an above average season for snowfall and deep cold at times.

Per SNOTEL, other NOAA sources, and Rutgers Snow Lab:

  1. The Eastern US had a below average season, not an average one. Better than some others though.
  2. California did have a below average season. So I got that right. We might see some improvements in the next little while, but not as fast as I expected.
  3. I got the Southwest pretty well too, slightly above average in NM, and somewhat below average in AZ.
  4. I got Utah pretty well, perhaps doing a little better than expected.
  5. Colorado went pretty well for my verification.
  6. I got this pretty well for the interior PNW/BC Rockies.
  7. PNW/BC Coast started slow (compared to a decent start for California IIRC), but came out better than I thought originally, with a very good second half of the season.
  8. I did reasonably well in the Great Plains, it was more average in the Midwest, and failed further towards the south. The Central US ultimately didn’t get the strong levels of snow and cold I predicted for this season.

So I did well across most of the Western US, underestimated the PNW Coast a fair bit, and overestimated the Central and Eastern parts of the US in terms of snowfall.

I had expected troughing over the Central North America, instead it angled towards the Northwest, with ridging through the Eastern US.

As always, lessons to be learned, to improve for next season.

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. I appreciate everyone who has taken the time to read the blog over the season, I will see you next year.

Japan in the long term 9th Feb

24th-26th Feb

GFS and EC Monthly Control show a snowfall event for Central Honshu and Hokkaido, starting on the 24th, after some rain for Honshu on the 22nd and 23rd. This roughly continues to fall in moderate-heavy amounts, until the early parts of the 26th.

March 4th-5th


Rain is forecast for Hokkaido and Honshu on EC Monthly on the 4th of March, after a dry week preceding. Moderate-heavy snowfall begins on the evening of the 4th, into the 5th.

8th-9th March

Rain is forecast from the afternoon of the 4th, overnight, easing in the early hours of the 5th. Cold air is absent around Central Honshu at this extent of the model forecasts.

Climate Drivers

The Arctic Oscillation is in a very strong state in the short-medium term, and is likely to remain so into the long term. We want to see it in the negatives, which of course hasn’t happened very often this year.

Between the +IOD dominated climatic state in the tropics, and the strong tropospheric vortex dominating in the extratropics, we haven’t seen the feasibility for a strong snowfall season in Japan this year.

The Siberian High has mostly been weak, bar for a few brief periods, for the Japanese snowfall season. This has meant that the winds that deliver most of the snow to Honshu have not been driven into the region.

The brief strengthening about a week ago probably helps to explain the good snowfalls that have featured in early February. But now we have seen the Siberian High go weak again, and this is likely to continue for at least the next week per GFS. This means conditions are likely to deteriorate again.

Why has this been so? A weak Siberian High and a strongly positive Arctic Oscillation are roughly interlinked. This has also meant that the +EAMTs that have occurred this season have lacked the capacity to really assert control, because the Siberian base state, like the rest of the atmosphere, has not been accommodating to a snowfall-bearing process.

But speaking of positive East Asian Mountain torques, we may have found the last light left in this season. The 13th-17th Feb period is likely to feature a strong +EAMT (watch the ridge move from Siberia downwards into East Asia, this is the actual process of a +EAMT from a MSLP perspective). This is likely to improve the Siberian High, and create some decent snowfall conditions for the 3rd week of February, possibly continuing through to the 4th week of February.

Afterwards, as projected by the models, I’m expecting a decline in snowfall-bearing conditions in the last days of the month and into March, once the strong +AO retains control in the last 10 days of February, and weakens the Siberian High again.

So basically a poor week ahead, some improvement in terms of snowfall in the last two weeks of February, and then another decline in the last few days of the month, probably continuing through early-mid March.

This will be the last edition of the long range snow blog for Japan this season. I am grateful for everyone’s support this season. The actual long range outlooks over the season have been relatively decent for me in terms of verification.

But of course we have to deal with the seasonal outlook I issued in very late October last year. I called for an above average season with an early start for Honshu, and Hokkaido was forecast to be a slightly above average season.

This was pretty much a failure for me. Despite a few early moments in November, December flat-lined, and the early start wasn’t so. The snowfall season was below average. It just didn’t work out the way I thought it would. So a lot of learning to be done, but hopefully we will do better next year with some new knowledge and hindsight.

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. For those of you who don’t watch my other NH forecasts, or the Australian forecast in a few months, I shall see you probably in September or October for a (less extensive for me) seasonal outlook period.

Until then, enjoy the remainder of winter and the seasons to come.

Europe on the long term 3rd Feb

14th-19th Feb


A ridge focused in Southern Europe, per EC 46 model, pushes the jet stream to the north, with an intense +NAO low driving a zonal outlook.

19th-23rd Feb

A strong +NAO and Greenland low shows a zonal pattern for the UK. European ridging dominates the Alps with a dry outlook for it.

24th-28th Feb

Ridging based over the UK and Europe driving a dry and bland outlook, albeit with a +NAO flow in the Atlantic.

29th Feb-4th Mar

A +NAO persists and most of Europe stills faces blocking, but a North African low makes it more interesting for parts of Southern Europe.

5th-9th Mar

Ridging pushes towards the NE slowly away from the Alps, with the Western and Southern Alps benefitting. The Pyrenees and parts of SE Europe also look like they are set to improve. A remaining +NAO like setup keeps Britain in zonal conditions.

Climate Drivers

GWO is currently in a very positive orbit that is contributing to more momentum in the atmosphere than normal. However this has not really translated to the higher latitudes at a strong enough rate.

Most of the strongly positive momentum deposits have occurred in the tropics and subtropics, which have little effect to patterns influenced from the poles.

What does this mean for Europe? Probably not a great amount of push to change the pattern.

There is snow in Britain’s forecast (at least according to long range GFS), but the vibe remains largely cyclonic with a mostly +NAO outlook being retained. So basically not going so much as the seasonal forecast went as expected.

The Alps are having a pretty reasonable season, with a very good start, and slowing right down for much of January, and now picking up with some recent snowfalls. So a bit up and down, a bit of a not so great, mundane season, which summarises much of the NH ski regions at the moment. This isn’t likely to change over the next little while, as there is no real credible deposits of +AAM in the mix towards the extratropics to change things up for Europe.

The one thing that could shake things up is a stratospheric warming event, and we are seeing some disturbance over the next week. The problem is that it is minor.

The overall trend looks pretty slightly upward after the disturbance, a weakening of the stratosphere and then somewhat of a restrengthening of the vortex. Potentially another disturbance is possible later in the month. The reality is that this is not going to make the impact we need to create a proper -AO scenario.

This is reflected by the models:

The AO per EC46 is positive for the next month and a half, while the NAO only makes it back to neutral in March. This shows that the present base state is going to be hard to beat, in terms of proper snowy outbreaks away from the Northern Alps, which will be assisted by the +NAO generated strong jet stream. The colder nature of February helps the UK, but it still sees a zonal outlook ahead with little sign of avail.

The MJO shows some signs of moving into Phase 5-6-7 in mid-February in some capacity, which may help to dampen the strong +AO base state down the line later this month (Phase 6 of the MJO plus 10 days teleconnects to a -NAO). But again, these sorts of changes are gradual. So don’t expect sudden change anytime soon, we will continue to see an up and down, largely underwhelming climatic outlook for most of the European snow regions. But we may see improvement later in February.

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.

North America on the long term 22nd Jan

Here is the long awaited North American update, with extensive analysis in the climate drivers section towards the bottom. Also includes model analysis….

4th-8th February

Per EC Weeklies, Labrador and Aleutian ridging hold a low over NW North America stretching down to the SE US. This would to bring snow and cold to the Central and Eastern US.

9th-13th February

A similar setup, but ridging to the south reduces impacts towards the north of the US, with Canadian troughing remaining.

14th-18th February

Ridging increases over most of the US, with Northern troughing pushed towards and into Canada. Aleutian ridging starts to move towards Canada, and a low grows south of the Aleutians.

19th-23rd February

-EPO ridging builds, reducing snowfall for Western US, but increasing it for NE US, driven by ridging building to the west and south, and laid out by the North Pacific low.

24th-28th Feb

The Aleutian Low continues to strengthen, and so does -EPO ridging. Troughing is restricted to the NE US and Atlantic Canada/Quebec towards Greenland, and just off the SW US.

Climate Drivers

CFS above shows the present MJO pulse, weakening into Phase 7/8, reducing the influence of the tropical wave. However it’s weaker, yet present impact still carries to the Atlantic. CFS notes hospitable tropical conditions for the long term in the Central/Eastern Pacific region, which may work well for the Eastern US.

However the opposite pulse through Maritime Continent will mean that there is unlikely to be another lap of the MJO around for quite sometime into February. Once the MJO signal fades, it is unlikely that we will have a strong tropical influence besides the lack of convection over Maritime Continent. This is probably not going to mean a sustained pattern change, and looks to more of a continuation to the up and down nature of the climate this year.

EPS-46 still shows that base state in the Western Indian Ocean (albeit slowly weakening in late Feb and early March), unlike CFS. It shows the same Maritime Continent conditions, but for a shorter period. EPS shows some sort of Phase 3-4-5-6 progression fo the tropical signal in Mid February. This is more likely to work out for the Western US, particularly with those earlier phases California.

The GWO (above) (represents extratropical impacts) is currently going through an abnormally positive orbit through GWO Phases 6 & 7. This has firmly established stronger momentum in a global context. The question is whether this is a once-off, or the sign of a new phase in terms of atmospheric conditions globally.

The vast majority of momentum has been added into the tropics, by the very strong recent MJO pulse. That addition of momentum has now subsided with the strong Frictional Torque back to neutral.

You can see above in the NH, the positive momentum in the poles and the negative momentum in the extratropics. Ideally IMO this would be reversed. The poleward mild +AAM deposits are just adding to a +AO state, which is benefitting the PNW/BC in terms of snowfall, and not so much for the Eastern US.

Strong mountain torque is expected to be sustained for a decent period of time, currently sustained by +MTs in North America and the Andes, and soon to be controlled by a strong +EAMT driven from the last few days of Jan into the early days of Feb. This is going to sink lots more momentum into the Pacific basin. We should see the impacts of this in the 5th-20th of February period.

So what I’d argue for is a change from the existing pattern that benefits the PNW/BC, towards one on the Western US that benefits the SW and California more for mid-February. I’d also argue that the mid-February period is likely to have elevated cold and snowfall risks for the Eastern US. This is all due to a jet extension of the North Pacific jet at it’s peak 7-10 days after the +EAMT event. We are also seeing some medium term trends of heading towards more equator-ward movement for the jet stream.

The one other block in this puzzle, the Arctic Oscillation threatens to dampen the impacts of this tropical to extratropical momentum transport.

EPS refuses to change its AO base state at all, as above. CFS also remains positive until late February, for a decent dip into the negatives during early-mid March.

In terms of the stratosphere, we have some decent wave-1 amplitudes coming through, leading us to this signal in 10 days:

As you can see this struggles to make much of a dent on the SPV, other than the typical slow demise, that does little towards changing the AO pattern. There’s still a chance of a SSW later in Feb or even March, but each day and each forecast that goes on reduces those chances.

  • PNW/BC/Northern Rockies to remain good for the next fortnight, reducing in the second week of Feb.
  • California/the SW/Southern Rockies to improve for the latter half of February (maybe a bit earlier)
  • Eastern US expected to improve for the last 15-20 days of February (2nd-3rd weeks of Feb, possibly into the 4th week) IMO.
  • These impacts may be reduced/weakened by Arctic influence, etc.

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.