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Snowy Hibbo

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    Melbourne, Victoria, Australia.
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    Meterorology with a focus on long range forecasting and climate drivers .
  • Weather Preferences
    Snowfall obviously.

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  1. https://longrangesnowcenter.blogspot.com/2019/01/europe-on-long-term-jan-19th.html An extract from my latest long range outlook below. "My overall view is that from the last week of Jan to the second week of Feb, will feature major snow risks for the Southern Alps and the UK. There will be plenty of cold around, but not so much snow for the Northern Alps. We should see a neutralisation in the later stages of the month." The outlook includes my thoughts on the GWO (click image below), and my thoughts on the latest EPS 46 run.
  2. I am not shifting goal posts, I'm saying that several troughs which brought snowfall to parts of the UK, which doesn't happen very often, and they brought some cold. Perhaps it did average out to be warm, but my point is that November featured more "interesting" weather, than December.
  3. In this age of AGW, cold in the way I described it is more like smaller very cold risks contained in a 10-20 day period, rather than a whole month. Plus the +AAM impact would have been like Nov 20 - Dec 10, not the whole of November. Cold is also a relative term, not to the climatology set long ago, but to the current climate and landscape. All IMO.
  4. What. That's an incorrect lesson. It's like going backwards. Take November for example. There was a high +AAM orbit in the GWO, and it shows it to that effect. And guess what the UK got.... GFS +6h forecast from the 21st of Nov 2018. The UK got a period of anomaly colder temperatures. We saw a -AO and -NAO from MSLP levels (not so much from upper fields). We saw westerly momentum coming off the NA Continent, displaced by the Atlantic ridge/-NAO setup to create this event, as perfectly as it came. November was remembered as cold for both the Eastern US & Europe. But if you look at what happens in December, it goes to low amplitude cycles around the COD, so you would expect a more neutral effect, that would be created by the +AO type of atmosphere to be not so good, as we have seen. So now the GWO is coming around (remember there is a bit of a lag too), we should expect cold associated with Phase 7 GWO in the next month, as these impacts are in feedback with the SSW, and take time. So basically the disappointment has been created by the ramp up of modelling and signals like the MJO, rather than the actual state of the GSDM. Keep your expectations calculated, and you will see success. And this attitude doesn't help as well. You place doubt in Teleconnections, and then you proceed to place all your forecast in the hands of models that have low verification. This verification that shows GEPS, GEFS and EPS all in one verification chart at T+360. Predictive correlation values fall below 0.2 at times, for both EPS and GEFS. And we are currently in one of those lulls in verification, given the SSW and AAM factors. There is higher verification in the forecasts Tele experts put out, than GFS FI, simply put. This is because one is NWP, and can't see everything amongst bias, and other factors. And the other is a comprehensive model that explains how the momentum and winds circulate around the world.
  5. Patience.... The background signals will come through, maybe not as one may expect. It's not like there is some secret magical mechanism that could make the weather worse than the signals suggest. It's a symptom of overreliance of NWP.
  6. Relax, all good things come with a bit of patience. NWP is not going to grant one a solution that features colder risks, because it's confused between the AAM amplification and the SSW impacts, which are slowly developing due to downwelling. It will come around. The latter half of the month should still be better. I just produced this post on another forum, that may help explain why I am feeling this way. Yes the more Nina-esque than expected tune through December was certainly not expected by me, with the +AAM being pushed back to New Years as it is now, but it is fortunately now here, and we are seeing impacts with the NP Jet extension in the next week or so (more on that further down this post). The low orbit of the GWO positive phase, that we are in, is because the relative AAM anomaly is low, with a substantial contribution from Earth AAM, contributing to the total AAM. The big November (as far as I can see from Australia) was largely generated by the +AAM. We saw that unprecedented spike in the AAM in the majority of November. But then you see that smaller +AAM spike from 5-15 Dec, and then now the current (total AAM) +AAM spike, which is nearing the level produced by the +AAM spike in November. The difference is what is driving it. Total AAM, sees relative and earth AAM combined, unlike what is seen in the GWO charts, which just have relative AAM. There is probably a reason for this (torques cover earth AAM?, it doesn't effect the Total AAM often, etc.), but it just shows that the GWO chart can't see absolutely everything, so should like every tool we use to forecast the weather, be examined with all of the GSDM tools that we are provided. But of course I'm not denying it's a good tool, it can see lots of things that the MJO, and the favourite the SOI cannot, but not everything. If we look at the relative AAM, you see the November spike, but a much lesser +AAM spike now for the current +AAM, and very little sight of the +AAM event from 5-15 Dec. . Earth AAM after months of stable neutrality, produced a relatively strong +AAM for the 5-15 Dec event, driving that total AAM spike. And now it is producing, alongside relative AAM, this large +AAM spike. It's very interesting to see this component come into play. The other thing I would like to add, is that I think this +AAM event will still produce what is intended (colder impacts for Europe and Eastern US), later in the month, along with when the SSW downwells into the troposphere IMO. We need to see the extra momentum, and then get the troughs into the extratropics (via SSW > -AO > HLB). Then the AAM can drop, jetstreams can drop a little and that is when we see the real cold. The timing could be a little off, but the second half of the month should still be good for the Eastern US and Europe. Europe quite likes a +AAM/GWO P 6-7-8 in terms of colder risks IMO, with the jet to push away the block over the UK. And you can see the +EAMT impacts are still on show well into mid-month, with a NP Jet extension, which will bring +PNA impacts after that extension weakens a little (without collapsing the Aleutian Low structure), and we see blocking in the Western US develop, and that brings troughing to the Eastern US. Along with the eventual -AO, downstream AAM effects will bring a -NAO later in the month. And I think everyone also forgets that the MJO Phase 7-8-1 impacts for troughing in the Eastern US, and Phase 7 MJO impacts towards a -NAO, all have a lag, depending on the location of impact and the tropical signal. The MJO and NAO connection features a lag of 10 days for example.
  7. https://longrangesnowcenter.blogspot.com/2018/12/europe-on-long-term-28th-dec.html My thoughts for the European Alps and the UK over January. And it's looking good, depending on the impacts of the SSW. The MJO looks to be pretty amplified, like the GEFS forecast. And the AAM looks pretty positive over the first two weeks of Jan.
  8. I will also add my musings to @Bring Back1962-63's post, which was on the same US forum. Just a few random musings from me. As you can see to start, we have a +NAMT right now. Look at the ridging to the East of the Rockies. This demonstrates a +NAMT. This is what is creating the uptick in MT anomalies, which @Bring Back 1962-63 observed above. But what you can also see, is that this quickly dissipates, under the pressure of lower geopotential heights. The Aleutian Low in the very short term, is going to dislodge very quickly, under the pressure of an anticyclone in the Pacific, as well as brief NAO/B-K Ridging. It splits off north and south, with the zonal circulation taking the former Aleutian Low south into the CONUS, to create a -NAMT, on accord of the breaking down of the Aleutian Low structure in the Pacific. It also creates/helps this beast, which I am sure is being well discussed in the shorter term threads. This is basically to show that the -NAMT is the mechanism or at least the reality of lower pressures like this. You need a strong jetstream to build the pressure, but you need something to release it. This is the releasor for this particular event. The much stronger releasing factor in a fortnight will be the SSW and it's tropospheric impacts in the AO domain. Apart from Days 5-6 which show more of an extension, it is consistently showing a poleward shift, which is due to the fact there is no low up in the Aleutians to keep the Jet down. But notice there is no retraction. The extension remains in place for the most part. You can see that in the 250hPa jetstream chart on Tropical Tidbits (not going to post pic, otherwise there will too many charts). It moves north, which will likely keep the steam train of snowfall events into the Pacific Northwest and British Columbia alive, and leave California and Tahoe rather dry in terms of precipitation and snowfall for the latter. This means I don't think there is such a massive -EAMT trend. We will see more -EAMT anomalies distributed in the next 3 days, but that is followed by a +EAMT event on GFS on D4-5. Then another -EAMT on D6-7, then the current Eastern European/Barents-Kara Block dislodges over the next 7 days, and comes down as a strong Siberian High, and links up to bring another strong +EAMT event for a good 3-5 days, boosting the North Pacific Jet. The +EAMT pattern stays until the end of the GFS Determ run (Day 8- Day 16 period). So it starts from the 24-25 Dec period, so with a 7-10 day lag, PNA effects to occur from New Years Eve into the New Year. Because it's so far out, it is hard to gauge the impacts of this with NWP modelling. Like do we get another Aleutian Low in the Xmas-NY inter period? Will it feedback loop with the developing SSW? All I will say is that it what goes down, must come up again..... does that work We should see the +AAM coming up again properly in the days leading up to the first day of 2019. I like something like the CFS GWO forecast below. Perhaps it may be a bit stronger in terms of Phase 5 and 6 orbit, but similar progression and timing (maybe a tad earlier though, but it doesn't really matter). Linking up with the SSW, that should be gold for the Eastern US for snow lovers. With a Stratospheric induced eventual -NAO, probably good for Europe as well in terms of cold. I will just continue the discussion quickly about the SSW. I don't think we will see a fully split Vortex, nor do I believe that a split matters in order to get desirable (snowy or cold) effects for the United Kingdom. We will see a technical SSW, and we will see very consistent w1 forcing, that will almost push it to a split vortex, but not completely. The options for genuine w2 forcing before the New Year are slim, and while I think there will probably be some sort of w2 forcing in January, as stratospheric alignments change, I don't think it will matter much, because the SSW, which will primarily take place in the next two weeks, will be pretty much done. There will be plenty of energy about in January (think +AAM), so there is an opportunity for sustained SSW conditions, which would enhance the tropospheric impacts, and would be the best option for an actual split. A displacement vortex doesn't typically bade as well for Europe, as it does for North America in terms of cold, but given the extratropical factors, I think a -NAO will develop and Europe will get it's cold. Maybe not record breaking, but it will be cold. The descending westerly QBO Phase isn't going to change these mechanisms much, it actually is climatologically linked with SSWs. Takeaway from all of that is the UK will get it's cold, given all of the surrounding positive factors.
  9. Zac Lawrence's new site is jam-packed filled with useful tools for the winter in the area of stratospheric forecasting.
  10. Snowy Hibbo

    The Seasonal Forecast Thread

    Here's my thoughts on how the forecast will go for the U.K. (And the European Alps). https://longrangesnowcenter.blogspot.com/2018/10/2018-european-winter-outlook.html Including analysis on the MJO, ENSO, NAO, Arctic domain factors, etc.
  11. So to prove your point, you show the tweet of a "professional meteorologist", asking whether the -EPO means cold. I am not quite sure about his credentials.... I would find someone else to prove your argument. And then the replier didn't support your opinion, he said it was "tough".
  12. So what is this then? Bottomline, whether the blocking is in the -EPO or +PNA domain, the downstream troughing occurs in Central and Eastern US, with the polar lobe coming down over the Mid West and bringing snow to the Mid-Atlantic/New England. And this further demonstrates the downstream effects. This is not to say blocking doesn't occur in the Eastern US, during a -EPO. I am just stating that a -EPO is correlated with a trough over the Central and Eastern US. That blocking over the Bering Sea isn't what I would call a -EPO, too much leaking into the Far East Siberian region, with the troughing off Western Canada too. That would be the WPO domain. With a -EPO and +PNA pattern, the below graphic shows Eastern troughing, in combination with other factors. Shows that there can be successful cohesion, which drives troughing on the Eastern half of the continent. Here was the EPO during your period, first half dominated by a neutral EPO, then a weak-moderate negative phase, then a weakening of the -EPO towards the end. Meanwhile the -WPO was nearly off the charts in strength, so clearly you have picked the wrong domain. The WPO and PNA domains don't cross, nor often correlate. So your statement of "HUGE -EPO RIDGE" is quite misleading. You also ignored the more -EPO like blocking from the 8-18 Sept this year, which was also a period subject to a +PNA.
  13. Snowy Hibbo

    Model Output Discussion - Autumn 2018

    With all due respect, you are wrong. A -EPO's downstream effects often create a Eastern trough. That is what it is known for doing, disturbing the polar jetstream up to Alaska, and bringing cold down to the Eastern Half of the United States. A -EPO if it stretches down towards the West Coast of America often gets called a joint +PNA and -EPO. So the assertion that a -EPO must go with a -PNA or vice versa is entirely misleading.
  14. Snowy Hibbo

    Model Output Discussion - Autumn 2018

    I realise I added to the case for an oceanic and atmospheric disconnect, but what if the ENSO is helping to signal, particularly with CP Nino regions being warm (along with EP Nino regions theoretically warming as well), and cold SST anomalies around Maritime Continent. This would help MJO and other equatorial waves to avoid Phases 4 & 5, and stay around Phases 7-8-1, particularly the former two phases. This is all for in terms of the winter, but can also apply to the present day.