Gavin P
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Posts posted by Gavin P
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GP's thoughts are very encouraging for coldies.
I can't understand though, why CFS and the extended ECM are steadfastly unable to pick up on these changes through January? -
From a personal forecast perspective, it means that, after having predicted a brief milder anticyclonic interlude followed by a return to colder stormy conditions around Christmas, then having backed down and considered various anticyclonic options, my original prediction is all of a sudden looking feasible again.
From a layman's perspective, it means that we will probably drift into a colder, windy westerly type around Christmas. It will probably be milder than what we've seen during the first half of December, at least to begin with, with some frontal systems bringing "warm sectors" and maxima near double figures in between the colder, showery polar maritime bursts, but for the longer term it could promote more "cold zonality" with chances of marginal snow events like the ones we're having now. Also, if pressure rises over Scandinavia, a NW-SE depression track will increase the chances of low pressure digging into Europe and rising pressure to the NE sending continental air our way from the east.
Stating the obvious I know, but the other point is that the further into the winter we go, the colder the potential cold zonality becomes, with more and more places at risk of snow rather than rain.
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B'astardi's really ramping about a SSW on Twitter today - Reakons it will pave the way to major cold across the US through mid and late January.
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Thanks GP.
Lots to keep an eye on then?
I must admit I don't really read JB's tweets (I do follow him) as most of them seem to be him ranting and raving about AGW.
I'll check out what he's had to say. -
Quite possibly the beginning of the end of this strong early vortex event..
Is this pretty much as you expected, or a few weeks earlier than you thought?
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its been clear for some time that mr vogan will be out with his timing. i wonder when he'll release a video to explain ??
Well, if by Dec 15th there are signs of RJS's pattern change over Christmas week, Mark will still be doing reasonably well, IMO.
I'm hoping Mark is there or there abouts, because I like his style. Unlike Madden/Piers/Powell, Mark Vogan at least explains whats going on and doesn't play the media game, as far as I can tell.
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RJS went for some notable storms in the first three weeks of December I think, with a final storm over Christmas leading us into a much colder pattern for the end of the month.
Mark Vogan also went for a stormy opening to December, but with a switch to a colder, blocked set up happening around December 15th.
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Hadley is confirmed as 9.6C, an adjustment down this month of only 0.1C.
That makes it the 2nd warmest November and 2nd warmest Autumn in the CET series.
http://www.metoffice...cetml1659on.dat
We now only need December to come in at 7.4C to beat 2006 and make it the warmest annual CET on record.
That would be the warmest December since 1988, so might not be quite as easy to achieve as it sounds.
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.. eventually yes Gav altough probably a bit too much inertia for it to fully develop until January.
Thanks.
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Probable further strengthening of the polar westerlies in the Pacific and Atlantic in time looks on the cards, and the trend for the shift of the core of the PV towards west of Greenland dropping into Canada looks rock solid to me (as per October winter discussion and winter forecast).
Does dropping the PV into Canda eventually teleconnect to allowing the ridge to build over Scandinavia?
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Fantastic work SB.
I wish I knew enough about teleconnections to make an indepth forecast like that. Wow. :oSolar activity is no guarantee of mild weather. Here's a list of months that fell in a max-solar year.
Feb 1947
Jan 1979
Jan 1917
Jan 1830
and these months were during years very close to a solar max
Feb 1956
Jan 1940
Jan 1929
Feb 1895
Jan 1838
Jan 1814 (a very good analogue for the overall solar trend)
Jan 1780
Jan 1740
The reputation of solar activity is really based on the Maunder minimum and the overall cold aspect of the Dalton minimum periods. Otherwise there is almost no demonstrable correlation. I did notice in my research that CET winters tend to be mildest about 1-2 years before solar max. This was not a huge spike in the data but otherwise the derived average was rather invariable when compared to solar activity. The list above is not meant to say that solar peak gives a cold signal, rather, that it does not prevent one.
I've always been lead to believe the important thing about solar max/min is not so much and max and mins per se, but the kind of max and mins within the cycle. For instance the minimum of cycle 23 was much longer and deeper than a normal min, so much more condusive to helping develop severe European winters.
Similar with maximums. The maximum of cycle 23 was very intense, hence the "write off" winters of the late 90's for cold.
So its really the strength/length of these cycles that counts in the end?
As the maximum of cycle 24 looks like being one of the weakest in the past 100 years, at no point should it on its own be enough to prevent cold winters (unlike the 90's when I think it DID play a big role in those write off winters) But of course all the other big drivers, such as ENSO and the PDO are still important factors in year to year variability.
Which averages are you using gavin?.... if 1981 to 2010 then you are going for 5.1C like me, i think you'll be very close.
Hope the rest of your winter forecast comes off too sounds like a pretty good winter for cold weather fans.
81-10
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The problem I have with 84/85 is that a lot of big drivers, PDO, AMO,ENSO and solar, were very differant that winter to now. The PDO was warm, now its cold. The AMO was cold, now its warm. We had a very weak La Nina that winter. This winter, whilst its still quite weak, its a stronger La Nina than 84/85. Solar activity was running down to the absolute minimum of cycle 21, now we're moving towards the maximum of cycle 24 (though its much weaker than you'd expect)
Personally I prefer the 1950's winters as a closer match to the current situation, and in particular 55/56.
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Indeed there wasn't, I personally feel that far too much weight is given to stratospheric warming events. As 87 shows we can get very cold spells without such warming.
My sort of crude rule of thumb is that SWW's are needed to get arctic/Greenland blocking. Scandinavian blocking is more about the jet stream and the relative strength and position of the Siberian High.
Of course an SSW would also help to get a Scandinavian High going, but its perfectly possible to achieve a Beast From The East without one.
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Good grief, poor Blast. This thread is turning into a character assasination of the poor chap.
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Winter 2011/2012 Forecast
This forecast is based on the following points:
1. Extended, weak solar activity and still below normal, but increasing sunspot activity.
2. Weak La Nina persisting into the middle of winter, before fading back towards neutral by spring.
3. Cold PDO/Warm AMO combination similar to 1950's (this is a wild card because it looks like the
AMO is becoming neutral or cold, which tends to favour troughiness over us, particularly when combined with La Nina)
4. October rainfall coming out at 94% of the average for England and Wales.
5. Active hurricane season.
6. Above average, but rather late snow cover across Siberia.
Most of the pointers I look at to compile a winter forecast are telling me the winter of 2011/2012 should be colder than average.
It would be very unusual to get a fourth colder than average winter on the bounce, however, I cannot ignore my methodology. So this forecast is going to predict a colder than average winter.
I'm thinking at least two of the three winter months will be colder than average.
DECEMBER:
I'm expecting December to be rather disturbed in the first half of the month, with quite deep areas of low pressure moving into the country producing wind storms,heavy rain and possibly snow. We should see big temperature variations during this period
Sometime around mid December I think we'll get a spell of high pressure, initially producing a mild, dry spell, but tending to become colder as the high becomes located over the country.
Christmas itself could be dry, cold and frosty with very little if any snow lying.
Between Christmas and New Year I expect a cold snap to develop, probably from the north, with wintry weather for many.
CET Temperature 0.5c above normal. Precipitation 100% of the average.
JANUARY
January might see cold and mild weather waxing and waning, but as we go into the later part of the month the emphasis will increasingly shift towards cold.
The New Year period should be cold and wintry, but then I'd expect a thaw as the weather becomes more Atlantic dominated for a time.
Mid month onwards we're at risk of increasingly cold and snowy conditions, though milder Atlantic air should push in for a time, once again.
The end of the month may turn very cold as a big area of high pressure develops over Scandinavia and brings winds around the east.
Temperature 1.0c below average. Precipitation 100% of the average.
FEBRUARY
February looks potentially the coldest month of the winter with high pressure dominating over Scandinavia and possibly Greenland also. The NAO/AO may go extremely negative, locking us into a prolonged and very cold spell of weather.
The first half of February may be the sevierest spell of the winter, with maxima staying around freezing all day and lots of snow and severe frosts as well.
The second half of the month should find low pressure attacking from the south-west as the blocking highs slowly lose their influence. So gradually it should turn milder with snow turning more to rain, though this could be a pretty slow process.
I think we end the month on a milder and unsettled note with snow confined to upland northern regions.
*I think there is a small, but not insignificant risk of February being a severe month on a par with Februaries of 1956 and 1986. At this stage I would rate this chance as around 25%. What goes against that risk is that I think the Atlantic will be attacking from time to time later in the month. This increases the risk of snow, but perversely also stops the cold from becoming too severe for an extended period.*
Temperature 2.0c below average. Precipitation 100% of the average.
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Sounds not unlike the epic cold January of 1940.
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WOW! Sounds like a stonking cold January! :o
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One thing if February is a cold month the snow doesn't tend to last long with the day's becoming longer I remember back in 2009 overnight snow fall was all gone by mid day thanks to the sun been higher than it is in November and December.
February can be outrageously cold - Colder than anything possible in December. Coldest December CET on record is -.0.8, coldest February on CET record is -1.9 Its just that we've not had much deep cold in February for a long, long time, so people have tended to become blase about what February can be like.
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I suspect Gavin they simply don't see that SSW which has been much discussed, so thats just leaving us in our current default pattern which is a number of variations of westerly.
Yeah, that might be it. But its strange though, because for the 2009/2010 winter CFS was on to that synoptic pattern from around September. And again for 2010/2011.
I've been quite undecided about this winter myself, because all of things I look at (nothing like as in depth as what GP does of course) Does suggest this winter should be colder than average, but the models refuse to come round to the idea, lol.
To be fair both the Beijing and IOD models are suggesting a blocked/colder winter, so not all the modeling is with CFS.
He goes into more detail about this in the full video which I've literally just finished editing and will have online tomorrow
Thanks Paul. Look forward to seeing it.
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Really interesting forecast. Thanks very much.
I wonder if Stewert has time to explain why he thinks the long range modelling (well CFS and ECM) is at such odds with what the analogues and teleconnections are suggesting should happen this winter?
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Indeed, after the next 7-10 day cooler slot, it may well turn that bit milder again as winds turn more west SW'ly as the mean axis of the trough pulls back west developing a ridge to our east.
Probably going to see 1 or 2 minor upstream amplifications for the main part of December but with tendency in relative angular momentum down and the polar westerlies now firmly developed, we need a substantive combination of wavelength change (time related) and net increase in tropical activity. Neither I would suggest are going to happen until we get to end December and even then these will be time lagged so in reality we are not looking at anything this side of New Year to get too excited about IMO.
If thats right, 2011 will be secured as an entirely snowless year here. Something thats never happened since I've been recording weather from 1993!
Looking forward to seeing your LRF soon, though from your postings on here, we already know your views on December.
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.. I have that ridge on the analogue package..
Note the position of the mean trough there, smack bang over the UK. I suspect we will see waxing and waning of the ridge to our north east throughout December as the jet oscillates in strength. Still no indication of high latitude blocking for another month at least given the polar westerlies, and no sign of the necessary surge in tropical forcing until perhaps late December.
Meantime, the model bias in terms of forecasting a -NAO has shown up again, with the pattern looking flatter as we hit the short to medium range.
That looks like potentially a very wet December pattern! Can't speak for anybody else, but would be most welcome here...
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I think a warming event in January is a really good bet, and I suspect the noises coming out of Exeter are also picking up on this.
A lot of the analogues I'm working with suggest a tropsopheric disruption in January. We will also have a renewed burst of westerly winds across the eastern tropics timed for around late December, so some evidence for the factors which can help to bring about a warming event 'ganging up' for around this time.
The analogues also suggest a monster MJO in February which should really help things move along once or if the warming event is underway.
I've been thinking for a while something like 55/56 could happen this winter.
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Anybody know whats going on with La Nina? It appears to have weakened quite a bit this week? Is this a temporary pause? Or have we had an early peak?
Now;
http://www.weather.u...ce/sst_anom.gif
Vs
A week ago;
http://www.weather.unisys.com/archive/sst/sst_anom-111106.gif
I can't understand though, why CFS and the extended ECM are steadfastly unable to pick up on these changes through January?
I'll check out what he's had to say.
In Depth Model Discussion, Analysis and Summaries
in Spring Weather Discussion
Posted · Edited by Gavin P
I agree with Stewarts Thoughts though, because they are very much in line with my own for this winter, which I've always thought would be mildish for December before getting progressively colder through January and particularly into February, so if he is wrong, I will be too.
When I got my own LRF together in November I did so knowing that the extended models weren't backing me up at all, but the broad thrust for my forecast (mild early, cold late) seemed like a no brainer for me, as all the signals I looked at appeared to point in that direction.