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The Seasonal Forecast Thread


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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

A great forecast layout by RJS with some tentative bullish comments in there.  I’ve got a hunch that verification stats could be very positive come the end of the winter.

 

BFTP 

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Posted
  • Location: oldham
  • Location: oldham
On 11/01/2018 at 21:53, Summer Sun said:

Met office maps have updated for Jan the next 3 monthly period of Feb to April looks mild and unsettled

2cat_20180101_mslp_months24_global_deter_public.thumb.png.a5a62c287196e8cd340a7e23334ada67.png2cat_20180101_prec_months24_global_deter_public.thumb.png.cc9f7535ceeb5be493892774b7aacae6.png

2cat_20180101_temp2m_months24_global_deter_public.thumb.png.c5c7f5a0f341b32d566d545cc8388ce7.png2cat_20180101_t850_months24_global_deter_public.thumb.png.ace5cb1d3ff4fa2ae07462a42b4408fd.png

Not sure it turned out that way.... (if it did it hid the Cold outbreak at the end of winter very well)

 

Lesson to be learnt here 

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Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada
5 hours ago, DR(S)NO said:

Interesting read Roger...my feeling is  the stormy spells may stem from the Northwest.... keeping it colder than average through these spells particularly for Northern Britain.

Or do you envisage them coming from a milder direction?

I would agree on your interpretation for northern Britain, as the overall scenario implies a tight gradient from about 250-270 deg perhaps and in later stages of stormy periods more like 290-310 so spikes in temperature may be confined to southern Britain and parts of Ireland. 

Just reading on the other thread (winter 2018-19) and apparently while I went out on a limb, various other weather scoundrels of note (re Express article) have found the biggest tree in the forest, climbed to the top, and I'm in danger of getting hit on their way down, or maybe they will just taunt me with a barrage of chestnuts (as long as they don't throw Bartletts should be okay). I am reassured to be back in the middle of the road (where we normally find roadkill). 

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  • 2 weeks later...
Posted
  • Location: Melbourne, Victoria, Australia.
  • Weather Preferences: Snowfall obviously.
  • Location: Melbourne, Victoria, Australia.

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.

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  • 1 month later...
Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

Bump

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Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

Things seem to be unfolding along the lines of the LRF that I posted, in terms of early winter being zonal with frequent storms especially at new and full moons -- the new moon occurs tomorrow at 0721z just about when strongest winds are being  recorded in northern parts of Ireland and western Scotland. The next lunar energy peak around the 21st-22nd should be pivotal to how the winter develops, if cold air can get established shortly after the expected stormy period then, it might settle in for a good spell.

I note that there was a major windstorm on 8 Dec 1886 and the interval from 17 Dec to about 17 Jan 1887 was quite cold, with a mean temperature close to zero degrees C. 

This is relevant mainly as a guide to how long it sometimes takes for a raging zonal period to transition to blocking and colder weather (although it was not especially mild during that particular storm with CET values near 4 degrees). The storm in question produced a record low barometer reading in Northern Ireland in the 920s, and 90-100 kt wind gusts over the Irish Sea with ships run aground on the Lancs coast. 

Edited by Roger J Smith
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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey
16 hours ago, Roger J Smith said:

Things seem to be unfolding along the lines of the LRF that I posted, in terms of early winter being zonal with frequent storms especially at new and full moons -- the new moon occurs tomorrow at 0721z just about when strongest winds are being  recorded in northern parts of Ireland and western Scotland. The next lunar energy peak around the 21st-22nd should be pivotal to how the winter develops, if cold air can get established shortly after the expected stormy period then, it might settle in for a good spell.

I note that there was a major windstorm on 8 Dec 1886 and the interval from 17 Dec to about 17 Jan 1887 was quite cold, with a mean temperature close to zero degrees C. 

This is relevant mainly as a guide to how long it sometimes takes for a raging zonal period to transition to blocking and colder weather (although it was not especially mild during that particular storm with CET values near 4 degrees). The storm in question produced a record low barometer reading in Northern Ireland in the 920s, and 90-100 kt wind gusts over the Irish Sea with ships run aground on the Lancs coast. 

delete

 

Edited by BLAST FROM THE PAST
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  • 2 weeks later...
Posted
  • Location: Live in NW Kent by the Thames & work in SE London
  • Weather Preferences: Snowy November to March and Sunny and warm April to October
  • Location: Live in NW Kent by the Thames & work in SE London

Someone posted in November a video link of the Meteo France winter forecast-which predicted a cold snowy December for the UK-safe to say that was very wrong at such a short timescale! Let's just hope many of the other models that went for a mild December followed by colder January/ February are correct!

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  • 2 weeks later...
Posted
  • Location: Carmarthenshire
  • Location: Carmarthenshire
On 08/12/2018 at 06:51, Roger J Smith said:

The latest (00z) GFS run starts to look like this scenario of cold engaging around Christmas, and there are some juicy charts on offer by 23rd-24th...

Roger, I wondered if you are intending to post an update on your winter LRF? From my novice perspective it seems your timings have been quite accurate (switch from mobile to blocking aroind Xmas) but perhaps the block hasn't set up as far north as you anticipated?  If so, does this impact your original forecast for a second cold spell towards the end of January?  Any thoughts welcome, always enjoy reading your LRFs.

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  • 1 month later...
Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

Sorry, I did not see the post above in real time, just came in here to offer a post-mortem on the winter forecast which failed to anticipate the mild trend but had some accurate comments about storminess and North American outcomes.

In essence, I think the trend line was the main problem, January (in particular second half) was colder than either December or February which was probably implied in the forecast, but all three months were probably about three degrees warmer than implied, December around 7 C, January around 4 C and February will once again finish near 7 C on the CET scale which will be a top ten winter average. Had January stayed as mild as it started, this would be a contender for the 1868-69 crown of mildest winter. It was only that interval (which was advertised to become exceptionally cold even on 10-day prog charts at times) that pushed the outcome away from the extreme category.

So I'm not sure whether a busted trend line with reasonably accurate variations over top of that represents a model error or the beginning of some sort of serious breakdown of the model's ability to cope with climate change signals. This will be one to monitor for several more seasons before getting close to an answer. I've always feared that if the AGW signal ever accelerated or if the magnetic field weakened substantially, all this research might become outdated by new realities. 

However, I think what probably caused the faulty trend line was that the ridge-trough couplet over Europe was further east than anticipated, allowing several prolonged cold spells to drop into central Europe. There was a tendency for the jet stream to drop far south in late January as implied in the forecast and that did lead to some exceptionally severe snowfalls in the Alps and heavy rains in Italy and parts of southeast Europe, with heavy snow added in other regions including northern Greece. 

As to snow in Britain, that amounted to almost nothing at lower elevations but I don't see that as an added model failure, it's just a consequence of the temperature trend failure. The late January colder spell did bring some significant snow to parts of Scotland and northern England, and one or two quite low overnight readings. Probably the forecast reads better in Scotland than in any other part of the British Isles. 

Events in North America have been much closer to what I was expecting and I can see that my forecasts are holding up because I'm either leading or second place in various snowfall contests and in the American weather forum temperature forecast contest. And the fields in those include professional forecasters (more so than here) which probably means less than you might suppose (pros have trouble with this too). 

There have been exceptionally cold intervals in central regions extending "at times out to both coasts" as stated, and I feel like I was ahead of the herd on the weakness of El Nino against the Canadian cold complex that had showed up early in the season. In fact, El Nino is out for the count with February becoming the coldest in many decades in the west, and snow instead of rain out to the coasts as far south as Oregon, and onto hills all over the southwestern US. The east coast has been relatively mild with a few brief cold spells, and not much snow. The heavy snow has fallen in the Great Lakes, Midwest, and northern New England regions, as well as pockets across the northwest U.S. (not so much into British Columbia which has been on the dry side mostly). 

So I am giving the forecast a D rating for Europe and a B+ to A- rating for North America. It's frustrating that the gains that I have made in my research in North America have not solidly transferred across the Atlantic, my research thread shows a lot of indications that it should enjoy a similar success rate with index values almost as strongly defined, but maybe it's my lack of feel for the climate of a continent where I don't actually reside, or a more challenging set of paradigms, that has caused this lack of equal progress. There has been progress if I look at all forecasts made since about 2005 when I expanded my efforts to the European theatre. But it's not a satisfying feeling of equal progress as the North American forecasts tend to stay in a fairly comfortable zone. These European ones have proven to be rather hit or miss, and the hits sometimes occur in situations that cry out with an obvious outcome like last summer which I never really felt was any sort of accomplishment to forecast heat and drought. 

Part of my own post-mortem will be to run the actual numbers against index values to see what sort of error trends can be spotted, because sometimes you can isolate a new research inquiry from that. I never thought that this research had reached its final stages, and have always expected to find new variables worth incorporating. 

As to the widely discussed SSW event that more or less failed to dislodge the mild pattern (obviously it was trying to do so around 21-31 January) I don't have much to say on that subject because I have assumed that my method would "back door" SSW events into the mix, although I have not succeeded in finding a cause and effect hypothesis that fits into the theory (was trying to link them from known occurrences but the data sets don't go back very far and it turns into a guessing game for 90% of the data I have analyzed). Then there's the MJO business, there again, I have tried to isolate research variables that might give a cause and effect predictive relationship with MJO, but if MJO also fails to do what it's supposed to do, then I sometimes ask myself, why bother with it? It could be like that Siberian early snow business, an interesting correlation but low-value for seasonal forecasting long-term. 

We're going to get to the bottom of this mystery eventually. It may be a couple of generations after you and I have moved on, but I can't see this remaining a permanent puzzle. It is interesting that ours is probably the only remaining science with so much mystery involved in it. I do know that whoever does eventually succeed will somehow have to "stand on the shoulders" of some of us who worked on whatever lines of research before them, but I can't really say with much assurance whether this will be part of it, or an accidental partial duplication of something totally different in structure, or irrelevant to the final result. My North American work convinces me that this is the way to go, and I can't really imagine a global paradigm in which it only works in one region, although I suppose you could have a situation where there's enough force in the connections to work where the magnetic field is strongest and not enough elsewhere reducing them to random energy dissipation zones. That would suck but the NMP is coming your way. :)

 

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  • 6 months later...
Posted
  • Location: Melbourne, Victoria, Australia.
  • Weather Preferences: Snowfall obviously.
  • Location: Melbourne, Victoria, Australia.

In terms of the 2019-20 Winter Outlook, so the countdown begins:
https://longrangesnowcenter.net/201...-seasonal-2019-20-winter-preliminary-outlook/
 

Some ideas here:

  1. A strong winter Aleutian low
  2. A +NAO favoured by models and Greenland ice cover.
  3. Perhaps some -EPO blocking
  4. A warm neutral ENSO state.
  5. A good outlook for Japan, Northern Alps and Western North America
  6. An opportunity at a decent winter for the Eastern US, per some indicators.
  7. And probably a wetter and more mild winter for the UK. That said, there is a good environment for SSWs, so we might see more -NAO like conditions later in the winter.
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Posted
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow
  • Weather Preferences: continental climate
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow
7 hours ago, Snowy Hibbo said:

In terms of the 2019-20 Winter Outlook, so the countdown begins:
https://longrangesnowcenter.net/201...-seasonal-2019-20-winter-preliminary-outlook/
 

Some ideas here:

  1. A strong winter Aleutian low
  2. A +NAO favoured by models and Greenland ice cover.
  3. Perhaps some -EPO blocking
  4. A warm neutral ENSO state.
  5. A good outlook for Japan, Northern Alps and Western North America
  6. An opportunity at a decent winter for the Eastern US, per some indicators.
  7. And probably a wetter and more mild winter for the UK. That said, there is a good environment for SSWs, so we might see more -NAO like conditions later in the winter.

looks like a horrible pattern for Europe in general.Not buying in to those models at all,there ought to be at least one winter with decent -NAO profile considering we had a long string of +NAO winters and are entering deep solar min + decent tripole

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Posted
  • Location: Longden, Shropshire
  • Location: Longden, Shropshire
15 hours ago, jules216 said:

looks like a horrible pattern for Europe in general.Not buying in to those models at all,there ought to be at least one winter with decent -NAO profile considering we had a long string of +NAO winters and are entering deep solar min + decent tripole

Knowing our luck they will probably be close to the mark!

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Posted
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow
  • Weather Preferences: continental climate
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow

Tropical Tidbits is very slow in releasing updatesd seasonal Cansip Model which was due on 1st September. Probably all time is consumed by Dorian watch

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Posted
  • Location: Edmonton Alberta(via Chelmsford, Exeter & Calgary)
  • Weather Preferences: Sunshine and 15-25c
  • Location: Edmonton Alberta(via Chelmsford, Exeter & Calgary)
On 02/09/2019 at 11:55, ICE COLD said:

Oh go on then let’s start early . Here’s the 850’s to go with your chart feb . Hope we see plenty of these come off . 

 

1CBE6CD7-6FBB-4982-8490-50980CAD447D.png

C4333246-4364-470A-B3D5-FB619CD2A56F.png

would be a horrendously cold start to the year here :cold:

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Posted
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow
  • Weather Preferences: continental climate
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow

CanSIPS Model has finally updated their seasonal outlook, it still goes with its last update from August. Plenty of Arctic blocking present, though also a lot of high pressure around North/Western Russia, so no real long fetch easterly signal there. T2M temperatures marginally below average for Western Europe with main through just to the east of UK.

november.png

December.png

January.png

February.png

cansips_T2maMean_month_eu_4.png

cansips_z500aMean_month_nhem_4.png

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Posted
  • Location: Essex Riviera aka Burnham
  • Weather Preferences: 30 Degrees of pure British Celsius
  • Location: Essex Riviera aka Burnham

Is there anything we can do to blast away high pressure from Europe?...the only crumb of comfort I can grab at currently is that the majority of this summer (since the end of June) we have experienced very little in the way of easterlies or on shore breezes (I live on the coast) in fact far less than previous summers and it has largely been a +NAO for this period and roughly looks to be the same for the foreseeable, if this pattern continues well into Autumn I'd be very surprised to see long spells into the winter...just a hunch no more no less, I did call last winter to be disappointing.

Edited by Froze were the Days
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