The Seasonal Forecast Thread

[VillagePlank]

My winter forecast. It's a bit late since I needed the published 30 Nov CET temperature.

 

This is, I suppose, the ultimate analogue forecast with respect to the year's CET values. I took every daily CET temperature (some 80k+ records) and I compared every days CET for every year and compared those values to every day to 30th Nov 2014. From here we can compute the Pearson correlation coefficient - how well it correlates.

 

Given that information we can order the results and find the the top ten years that match this year. Here they are

 

 

These correlations are far too high to be generally useful, but they do serve as an ordering index. They are too high because I didn't take the seasons out, so of course warmer summers and colder winters do correlate.

 

Taking the top five years, here's the averages,

 

 

Looks to me to be all over the place and of dubious merit.

[A Winter's Tale]

DECEMBER... A close to or slightly below average month with an unsettled and changeable first half with active weather fronts sweeping the country and areas of low pressure often close by to the north, delivering frequent windy and blusetry conditions, occasionally turbulent and it will be predominately below average in the north with intermittent wintry precipitation, slightly milder and calmer further south with some settled intervals from the SW introducing a few frosty nights. It should remain unsettled into the first part of the second half of the month, with a change to a more pronounced spell of milder weather before becoming colder again with an anticyclonic period preceeding a cold and wintry spell to end the month with an Arctic sourced airmass. Temperatures 0.25C above to 0.75C below average, most likely to below average further north. CET 5.2C. Rainfall 90-100% of the average in the south, 95-110% of the average further north and west. Precipitation coming in the form of rain from active weather fronts and proceeding some blustery and unstable airflows with some intervals of wintry precipitation in the north west and potentially significant totals of snow on the Scottish high ground. Sunshine 5% on either side of the average.

JANUARY... Colder or significantly colder than average with a return to unsettled and potentially stormy weather for a time after New Year with temperatures generally around or just above average prior to colder, anticyclonic conditions before mid month, heralding a risk of harsh frost and dense patches of fog. It should turn significantly colder for the latter half of the month, with increasing chances of snow in most places but especially in eastern and southern areas with the possibility of some significant snowfalls. Generally drier and more settled further north. At times turning less cold in the very SW but generally very cold, at times intensely cold elsewhere, with widespread and at times severe frosts. Temperatures 2.0C to 0.5 below average. CET 2.2C. Rainfall 90-110% of the average in the east and 75-85% further north and west. Sunshine 5-10% above average in the north and west, 5% below average in the east.

FEBRUARY... Colder than average, especially in the first half of the month with prolonged and at times intense cold pesisting into the new month. It may become more anticyclonic at times with high pressure close to the north and snow showers becoming lighter and infrequent. However, there may be a few attempts of the Atlantic making enrodes, resulting in a few oppurtunities for battleground snowfall. Eventually, the atlantic should win resulting in milder and changeable conditions from the west, perhaps the risk of a wind event or two before becoming much milder to end the month. CET 2.9C. Rainfall 65-85% of the average in the south, 75-85% further north. Sunshine 5-10% above average.

[Man With Beard]

My seasonal forecast

 

3-7 December 2014: The entrenched cold front arrives, harsh frosts every night and temps as low as -5C but not snowfall.

8-15 December 2014: The cold really kicks in now, highs of -3C for the early part of the week, possibly edging above freezing in the latter part. 2-5cm of snow this week.

16-22 December 2014: The cold kicks in even harder Mon-Thurs highs of 1C and lows of -10C with highs of -11 and lows of -20 widespread by the end of the week. Around 25cm of snow will accumulate Mon-Thurs; too cold to snow for much of the end of the week. Permafrost possible,

22-29 December 2014: Week fairly consistent highs of +/- 2C with lows of around -10C on lowlands. Around 50cm of snow for the entire week, with 25cm of that falling on christmas day.

29 Dec - 4 Jan 2014: More of the same, further build up of snow between 60cm and 90cm within Mon-Fri and a further 120cm-150cm over the weekend. Temps staying relatively mild at -3C to 3C for much of the week.

4-11 January 2014 - No snow this week, clear flies and harsh frosts. No melt either as temps ranging from -20C lows to -9C highs freeze the snow.

12-18 January 2014 - Similarly to last week, low temperatures of -18C to -9C highs.

19-25 January 2014 -  The temps warm up a bit with lows of -4C by the end of the week, highs around 2-3C. Around 45cm of snow on Monday, dry to Thursday and then around 500cm in harsh blizzards on Saturday night into sunday dawn (falling a 60cm per hour).

26 Jan - 1 Feb: Temps decrease again, snow freezes and temps around -11C highs and -30C lows widespread, much colder in mountainous areas.

2-8 Feb: Mass snowmelt begins with a warm front coming in from the south west. Mass temperature increases to around 11C low and 15C high - melt snow extremely fast, with issues further compounded by 

9-16 Feb: Flood relief efforts hampered by widespread gusts of between 110mph and 180mph. These come from the north bringing with them heavy snow showers, although little accumulation on mostly sodden ground.

16 Feb - 1 March: The conditions turn spring like with average temperatures and little precipitation.

I'd love to see the pressure charts for this - let me guess: Atlantic/Greenland block in situ for 6 weeks?

[Roger J Smith]

Wowsers, I feel like such a mild ramper now.

 

I don't think I went below -20 or over 50 cm of snow even once. Ian Brown, move over.

[BLAST FROM THE PAST]

I've always told you that Roger......

 

BFTP

[Roger J Smith]

The 12z model runs have the door fairly wide open to the Greenland high linking to a somewhat retrograde Azores high, then they have a tendency for this to shudder back to the east which I think is about what may happen, don't expect this severe cold winter to materialize and lock in, there will be a two week battle for supremacy starting around 22nd Dec and ending with a victory for cold around the 6th to 8th of January. In between it could become quite stormy especially towards the end of that period. Although I gather that the forecast quoted above is meant to refer to northeast England I would expect something a bit less extreme to verify elsewhere, but certainly every chance of a tabloid-selling sort of winter ahead. Mind you, almost every winter since 2009 has had something fairly extreme at some point with just last year going down the extreme mild path (as well as the non-stop windstorm route). Maybe 2011-12 was a bit on the bland side in western portions of Britain and in Ireland, otherwise we have seen a pretty dramatic turnaround from the old "mod'urn win'ter" days that had us singing about a Bartlett in a pear tree.

 

The average of all forecasts on here is about what the official NW forecast says, I think. So we are pretty much all in the same boat with variations, will be interesting to see if that generally works out and then whose details seem best at the end of play.

[BLAST FROM THE PAST]

If January cold does win out then what I have in mind this winter will be up there with the very best for longevity and depth of cold and snow.  I think this December has the potential to catch a lot of people out with cold and snow potential.

 

BFTP

[Gavin Hannah]

If January cold does win out then what I have in mind this winter will be up there with the very best for longevity and depth of cold and snow.  I think this December has the potential to catch a lot of people out with cold and snow potential.

 

BFTP

 

 

Well December 09 and 10 both provided the UK with a shock start to winter.  In 09 if i remeber right, it was around the 23rd and in 10 it was around the 18th?

 

Waiting to see what the evolution is like over the coming week and keeping my fingers crossed!

[damianslaw]

Well December 09 and 10 both provided the UK with a shock start to winter.  In 09 if i remeber right, it was around the 23rd and in 10 it was around the 18th?

 

Waiting to see what the evolution is like over the coming week and keeping my fingers crossed!

 

Dec 2009 - proper cold set in on Thursday 17th with a bitter easterly piling in snow showers to eastern parts, cold conditions had set in weekend prior with frosty conditions but it took until 17th for deep cold uppers to invade.

 

Dec 2010 was bitterly cold from the off, the actual proper cold set in on the 24th November, and only relented from the 27th onwards. However, there was a plunge of arctic air on Thursday 16th and 8-9 days of sub freezing conditions set in for many thereafter. The two Decembers following saw a role reversal of sorts, with a slightly colder than average spell of weather in 2011 breaking around the 18th, in 2012 a cold first 12 days broke on the 13th and we saw a mild second half. 2008 also quite similar a cold first 2 weeks then a much milder spell in the run up to Christmas. I'd much rather have a Dec 2009 than a 2008 or 2012 which although saw cold wintry first halves denegerated into mild mush in the run up to Christmas, whereas Dec 09 started off mild but the cold arrived with perfect timing..

 

Looking at prospects this December - very mixed signals, if it does turn milder after next weekend, I hope it is only for a few days with a change occurring around the 20th.

[sebastiaan1973]

https://twitter.com/BigJoeBastardi/status/541936597051392000

Love the Look of the ECMWF seasonal 500 mb. Right to the http://weatherbell.com  analogs!

Does anyone have access to this seasonal forecast?

 

Thanks!

[Tim]

My seasonal forecast

 

3-7 December 2014: The entrenched cold front arrives, harsh frosts every night and temps as low as -5C but not snowfall.

8-15 December 2014: The cold really kicks in now, highs of -3C for the early part of the week, possibly edging above freezing in the latter part. 2-5cm of snow this week.

16-22 December 2014: The cold kicks in even harder Mon-Thurs highs of 1C and lows of -10C with highs of -11 and lows of -20 widespread by the end of the week. Around 25cm of snow will accumulate Mon-Thurs; too cold to snow for much of the end of the week. Permafrost possible,

22-29 December 2014: Week fairly consistent highs of +/- 2C with lows of around -10C on lowlands. Around 50cm of snow for the entire week, with 25cm of that falling on christmas day.

29 Dec - 4 Jan 2014: More of the same, further build up of snow between 60cm and 90cm within Mon-Fri and a further 120cm-150cm over the weekend. Temps staying relatively mild at -3C to 3C for much of the week.

4-11 January 2014 - No snow this week, clear flies and harsh frosts. No melt either as temps ranging from -20C lows to -9C highs freeze the snow.

12-18 January 2014 - Similarly to last week, low temperatures of -18C to -9C highs.

19-25 January 2014 -  The temps warm up a bit with lows of -4C by the end of the week, highs around 2-3C. Around 45cm of snow on Monday, dry to Thursday and then around 500cm in harsh blizzards on Saturday night into sunday dawn (falling a 60cm per hour).

26 Jan - 1 Feb: Temps decrease again, snow freezes and temps around -11C highs and -30C lows widespread, much colder in mountainous areas.

2-8 Feb: Mass snowmelt begins with a warm front coming in from the south west. Mass temperature increases to around 11C low and 15C high - melt snow extremely fast, with issues further compounded by 

9-16 Feb: Flood relief efforts hampered by widespread gusts of between 110mph and 180mph. These come from the north bringing with them heavy snow showers, although little accumulation on mostly sodden ground.

16 Feb - 1 March: The conditions turn spring like with average temperatures and little precipitation. 

 

Is this you James Madden lol?

[Dorsetbred]

Is this you James Madden lol?

Yes not looking good from December 1st one has to say.

[BLAST FROM THE PAST]

Many are explaining the reasoning but we have had one heck of an AZH rut which has only teased on occasion northwards in the Atlantic......hasn't played ball with my forecast.  When the intial ridging started as I thought, I thought bingo we are on.....then it flattened blowing my Dec out.....maybe I should have gone with my 'concern' that the cold may arrive later than expected...because it hasn't arrived yet! 

Never mind, lets see what Xmas and New Year brings and see if my SSW forecast of being possibly biggest story of Jan comes through.

oh for the 06z P.

 

BFTP

Edited December 16, 2014 by BLAST FROM THE PAST

[Roger J Smith]

This month has been very similar to Dec 1962 in North America, and looks to remain on that course to end of the month as well.

 

Noting that the 62-63 winter cold did not really set in with any vengeance in the UK until just before Christmas, so that possible analogue is not really too far removed from current trends given that the past two weeks have been a bit colder than average in a lot of places in the UK and Ireland. Next 72h looking very mild but all models are showing hints of a gradually dropping jet stream and a big clash of air masses due around 28th which I think will culminate with some particularly violent storms just after New Years.

 

I think there will be big happenings this winter, and some intense if not extreme winter synoptics down the road. Anyway, very few winters were decided before Christmas, this one probably won't be remembered for the next three days' contribution.

[damianslaw]

Some of the coldest spells of the past have been preceded by mild/very periods, winter 62/63 sort of a case in point, winter 46/47 notably so. The change to cold weather in Dec 09 came on the back of a very mild Nov and start to December. Cold in Jan 85 on the back of quite a mild December.

 

Many forecasts were suggesting cold proper won't set in until Christmas period.

 

I always think Christmas - New Year is a pivotal period, it is often a very volatile period of the year, when the northern hemisphere slumps into its mid winter state proper - rarely is the set up for the winter as a whole set before Christmas, last year was an exception in point - notably so. If we take winter 09/10 as a good example it was only just before Christmas we saw the pattern change to colder weather. The exceptional cold and blocked nature of December 10 came to a crashing end during the Christmas-new year period and thereafter we were left with mild westerlies in the main.

 

Another good example of a winter which changed around Christmas was winter 78/79 when we saw low pressure dig southwards, winter 00/01 saw a change around Christmas period as well to a much more blocked set up. Winter 01/02 saw a change at new year to a very mild atlantic fest after a rather wintry Dec at times.

 

Indeed I don't think there is on average a more varied week in the whole year than the Christmas week, from bitter cold to mild long fetch southwesterlies and such rapid change likely to occur in such short space of time..

[BLAST FROM THE PAST]

Interesting this possible pattern change which is gathering momentum.  Folk have mentioned elsewhere that deep cold spells have arrived for UK before any SSW event, if this one happens this will be another example.  I've got SW event for early to mid Jan hence my Feb thoughts and delayed Spring.

Anyway those that went for delayed cold [wish I had as synoptically its shown to be developing the right way] are 'currently' looking very good.  I think Xmas will still be an active period but looks like a cold active period.  There does seem to be a massive shift building and I think most think that this winter is going to go 'BANG' as some point. 

Interesting post from RJS...

 

BFTP

[Zenarcher]

My monthly forecast for January 2015 can be read here https://forum.netweather.tv/blog/227/entry-4859-january-2015-forecast/

[BLAST FROM THE PAST]

As in the strat thread there has been talk thus far of this winter being frustrating and I have to agree and mentioned that this PV has been resilient despite all the 'good' early signs, and still looks like holding on.  I'm very much wondering whether we are in danger of the milder flow taking real hold.  The block to the east hasn't materialised and is 'nowhere to be seen' currently and for me now we do need this SSW [which I still think will occur early/mid Jan] to claw us out of a pretty average winter thus far.

Edit - Average 'overall' some have had some decent wintry weather and I tell you what its been darn cold this Christmas....as from earlier post a cold active period over Xmas.  I think Jan has some surprises up its sleeve like December but don't expect deep cold,,,,until backend when SSW effects will be showing in the models 

 

BFTP

Edited December 30, 2014 by BLAST FROM THE PAST

[Mark Bayley]

 

2014/15 Winter Forecast 

 

 

Factors considered

·         QBO

·         October snow cover

·         Autumn sea ice extent

·         ENSO

·         Solar output

·         Long range models

·         OPI (briefly)

 

 

Autumn sea ice conditions

Snip < This year sea ice extent was negative, however not as low as years previous. Sea ice extent was also higher in the aforementioned regions, thus it may be expected that this year’s sea ice anomalies potential to force -AO may be less strong than previous winters. Despite this sea ice extent is still at record lows, and based on other climatic feedbacks, I’d suggest is still supportive of a colder than average winter. >

 

October sea ice extent

 

Summary

I favour colder than average winter with at least one month to return a notable -AO figure. At present I favour January with a significant stratospheric warming event to occur during late December/early January based on the strats present situation and a gut feeling, but also Cohens work on when warmings are most likely to occur (see strat thread). February may produce the greatest -AO return based on snow cover analysis. December may prove to be mildest month, although with a disrupted PV, colder spells would seem likely, as shown by the reanalysis. Thank-you for reading J

 

Unfortunately my forecast has so far been wrong (December and January). The polar vortex has remained relatively strong and will no doubt remain fixed across Greenland for the foreseeable future. This is despite stratospheric warmings and continued atmospheric wave activity. December was expected to the mildest month, however i favoured a greater number of cold spells and for the AO to be neutral/negative, as opposed to mostly positive. A significant stratospheric warming event was forecast for the end of December/early January. This has not and will not verify till at least the last 1/3 of January, in which case the impacts may only be felt for the very end of the month and February.

 

Seemingly a number of favourable factors have been overridden. IMO sea ice conditions in the Barents/Laptev/Kara seas has acted to reinforce low geopotential heights (i.e. an intense polar low) that has inhibited the formation of a strong Siberian high as suggested by the Cohen snow cover theory . As hinted in my initial forecast, sea ice anomalies in these regions was near normal and higher than previous years. I suggested that the sea ice anomalies potential to force -AO may be less strong than previous winters. Rather than a reduced influence, sea ice conditions may have acted to sustain the +AO and +NAO pattern so for experienced this winter. Of course, i am no scientist, so could be entirely wrong! Further to this, other climatic variables that may have come to our aid, such as the MJO, have failed to gain amplitude to the phases that we desire. 

 

Am writing off winter? Certainly not! I think we can be confident that the first half of winter (Dec 1 -Jan 15) will not deliver the sustained cold and snow that many of us crave. The PV is resistant across Greenland, with the Azores high to our south remaining notably close (as shown by most deterministic long-range models). The best we can hope for, imo, is for the azores high to weaken and for troughing to sink south and eastwards, giving us shots at colder zonality. This has been hinted in the long term. There are hints from the GFS of progression of the MJO towards phase 7, offering a possible pattern change post mid-month (MJO 7 teleconnects to a mid-Atlantic ridge). However, many models such as the ECM remained locked in phase 5, suggesting low heights across the UK, but may offer support to colder zonality. Unfortunately, the ECM returns the MJO to 'circle of death'. Further stratospheric warmings and wave breaking will no doubt pressure the PV, although im uncertain as to when the knockout blow will occur. When it does, we may be game (depending on what gets sent where!). The last 1/3 of January/February now offer the best hope of sustained cold/snow. February still has every potential for delivering a significant -AO month 

Edited January 2, 2015 by Mark Bayley

[damianslaw]

Good to see some people posting how there winter forecasts are shaping up so far. Indeed its never plain sailing making any forecast - and certain factors  can easily cancel out other factors to create the default seasonal pattern we normally expect - which is atlantic westerly with temporary settled colder shots.

 

Would be good to hear other people's perspectives on things so far.

 

Winter as a whole as a long way to go (indeed for the north first half of March qualifies as winter in my book), and in an average year settled colder conditions are statistically far more likely to surface during the second half than the first half - so those who have forecasted a generally colder middle-latter part of winter still have plenty of time to save 'face' despite the current signals showing no easy ride to sustained colder pattern. Winter 11/12 is a good example of a cold spell occurring in the second half of the month despite very unfavourable signals for such weather, yes it was shortlived but it was quite lengthy roughly 28 Jan - 12 Feb, with a week or so of snow cover for quite a few and near sub freezing means.

 

If we look at Januaries since 1987, only a paltry 2 could we be described as a returning a predominantly cold first half these were 1997 and 2010. 2009 was quite cold but not in the same league. Otherwise all others (and that's 24 of them!) saw either average temps or more often than not mild sometimes very mild conditions with a mostly mobile atlantic pattern. The second half of January however, has seen much more varied fayre with colder wintry conditions predominating in a greater number of years compared to the first half - examples being 1991, 1992 (the cold dry frosty type), 1996, 2001, 2013 and some northerly outbreaks (1994, 2003, 2004), others though in the main just returned more of the same (1988,1989, 1990, 1993, 1995, 1998, 1999, 2000, 2002, 2005, 2006, 2007, 2008, 2011 and 2012 (tail end excluded), 2014 - oh dear how poor many Januaries have been for cold weather in the last 27 years!, but the clear trend has been for colder conditions to more likely surface in the second half compared to the first.

Edited January 3, 2015 by damianslaw

[BLAST FROM THE PAST]

So we enter a stormy period, could be a few surprises up its sleeve this month.  Don't know why I didn't mention it in LRF as I did in the other months, but we are in Full Moon and Apogee period which should have [for me] struck a chord.  Anyway there is a stratospheric warming going on [not a major one but a SW nonetheless] so we are not in bad territory and I think there'll be ramifications down the line for this.

Looking ahead what am I anticipating....well fortunately its not developing in too mild a month or indeed outlook, some pretty chilly weather on and off to come.  I'm also/really focussing on my period 20/21.  Another stormy spell around then, LP/s likely not to be as deep but could be more of a player/s as I anticipate developments to our E/NE [could be a HP or it could be heights trying to build] to induce a more southerly track with even sub lows going into near continent thus affecting more of the UK [direct hit] and a negative tilt so a SE'ly flow could develop.    I think the current warming may assist in such a development that may then lead to a winter kick start for end of month into Feb.  It could all be further north if it pans out which is another kettle of fish.  Talk of Feb I'm thinking that the PV will drop this side of the hemisphere and a very cold volatile regime will set in.  Winds from NW to NE quadrant.

Just some musings but models currently adding some interest into this in deep FI [pinch of salt noted] but I am quite hopeful that winter has some punch to pack yet and the SW that has occurred and the timing of it instills confidence of Feb.

 

 

BFTP

Edited January 10, 2015 by BLAST FROM THE PAST

[BLAST FROM THE PAST]

So timing wise I'm pleased with this, that could be impactual inasmuch that heavy precip of snow.  For me solar influence has caused this 'flip' to bring these synoptics which look reasonably on the money.  The Strat Warming we had is showing its effects and the perigee/mew moon could pep this feature up somewhat so wouldn't be surprised to see upgrading in its impact.

 

BFTP

Edited January 14, 2015 by BLAST FROM THE PAST

[oasis]

I think Roger Smith deserves a few kudos for his winter forecast. Not entirely accurate, but certainly predicted after new year storminess, along with mid January cold spell. Will the super cold February materialize?

[Roger J Smith]

Thanks, I probably damaged my original forecast with the update but what does appear likely to verify is a higher variance than normal, at least the way things are now looking. I could certainly imagine this evolving into a very cold February, but the Atlantic seems to have some fight left in it and we might just get a chaotic mix of all sorts from here to spring.

[BLAST FROM THE PAST]

Thanks, I probably damaged my original forecast with the update but what does appear likely to verify is a higher variance than normal, at least the way things are now looking. I could certainly imagine this evolving into a very cold February, but the Atlantic seems to have some fight left in it and we might just get a chaotic mix of all sorts from here to spring.

And the Atlantic could be a 'friend' re snow prospects Roger.   Certainly benign isn't looking the word

 

BFTP

Edited January 14, 2015 by BLAST FROM THE PAST