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Winter 2010-2011 outlook
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M.T. Cranium wrote: »I am still calling for a winter storm setup to develop with the full moon event around 20-21 December, and the models continue to hint at a reload of very cold air from the north or northeast before that time period so it seems the chances are reasonably good for a white Christmas. All of this is of course less reliable than 3-5 day outlook forecasting, but looking back to post 767 in this thread (15 Nov) not that unreliable. :cool:
Thanks for reply m.t,white christmas would be nice for once
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M.T. Cranium wrote: »I am still calling for a winter storm setup to develop with the full moon event around 20-21 December, and the models continue to hint at a reload of very cold air from the north or northeast before that time period so it seems the chances are reasonably good for a white Christmas. All of this is of course less reliable than 3-5 day outlook forecasting, but looking back to post 767 in this thread (15 Nov) not that unreliable. :cool:
Indeed MT, I dug out your forecast last night and spot on
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this MTM.T. Cranium wrote: »Time to confirm what I've been hinting at here and in the daily forecast thread.
My long-range seasonal outlook calls for colder than normal temperatures for most of the winter months, and higher than normal snowall amounts.
Expect periods of very cold weather to develop late November and through much of December as blocking high pressure becomes well established over the Baltic regions. While the Atlantic will occasionally push back and bring milder, wet conditions, the frequency of east winds and cold combined with a storm track close to the south coast of Ireland and into the southern half of the U.K. should make for frequent snowfalls in many parts of Ireland and the U.K. Predicting temperatures to average 1.5 to 2.0 C below normal in December and some stretches possibly sub-freezing, with snowfall likely before Christmas making for a white Christmas for many.
The January outlook calls for this cold to deepen for part of the month before a brief reversal indicated by some of the research index values. Therefore the month may feature some major winter storms mid-month as this pattern reversal begins. Despite the milder end, the month is likely to continue to average below normal by about the same amount as December, 1-2 C and possibly more.
February was less conclusive from the research index values but unless the January reversal is highly energetic, could see the blocking redeveloping and leading to a colder than normal February as well.
Given the strength of cold in the outlook and the dependence of mean winter temperatures on snow cover near the lower end of the spectrum, one cannot rule out a sort of near-extreme or even extreme outcome, since mean monthly temperatures below 2.0 tend to promote continuous snow cover and therefore a fairly easy slide down to sub-freezing values from the same air masses as are present for 2-3 C.
In other words, I'm predicting a cold winter with lots of snow, that could become an epic winter. Stay tuned.
One other detail to note, the storm frequency from my research should be on a fairly well-modulated 3.5-day cycle with stronger events every seven days or so (this is not exact so it won't work out to the same day every week). The stronger events are likely to produce their share of slow-moving but deep "Channel" or French lows promoting a strong east wind and outbreaks of snow. One of the better scenarios I foresee for snowfall comes with the December full moon and "northern max" event of 21 December. This is bound to produce an intense storm over western Europe and I am giving something like 2-1 odds for this to be a cold weather storm event with at least some snow or sleet in the mix for Ireland, whereas if the pattern happens to be stuck on mild then, look for a very mild and windy sort of event followed by much colder weather.
In general, through the mid-winter period, the stormy episodes will fall at full and new moons, and approximately mid-way between them with a second set of high-energy peaks. This pattern will continue into late winter but with the secondary energy peaks decoupling from the primary (full/new) this gives a more frequent distribution of storms that, if coupled with a cold pattern in February, could lead to a steady parade of disturbances around the southern flanks of blocking high pressure to the north and northeast.
Anyone interested in a more detailed forecast could find one later today on Net-weather posted by my research associate and friend, Blast from the Past as he is known to the weather forum world. That will be UK-centric but after all, the winter patterns are bound to be quite similar, and the general theme appears to be cold winning out over mild again this winter.
Looks like this pattern could be setting up gradually later this month, and I would not be surprised if there is some snow even in late November.0 -
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thetonynator wrote: »I know its way into FI and i wont even bother posting the charts, but the GFS has the cold breaking down soon after it starts around the 20th or 21st . . .and they have been remarkably accurate up until now. You're joking right?
They touch every scenario in FI, 28 outputs per week
Even the 0z,6z,12z and 18z in the same day are often chalk and cheese.0 -
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Jerry Seinfeld wrote: » You're joking right?
They touch every scenario in FI, 28 outputs per week
Even the 0z,6z,12z and 18z in the same day are often chalk and cheese.
The GFS was giving this cold spell well in advance, it caried every day but it kept coming back to a similar scenario. Look at the winter FI thread, -8 850 temps were predicted well in advance. I'm not saying they were infallible or anything like it, but compared to the usual it was much more accurate.0 -
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THE RECENT COLD SNAP AND WHAT LIES AHEAD?
WHAT IS THE ARCTIC OSCILLATION?
“The Arctic Oscillation is a climate pattern that influences winter weather in the Northern Hemisphere. It is defined by the pressure difference between air at mid-latitudes (around 45 degrees North, about the latitude of Montreal, Canada or Bordeaux, France) and air over the Arctic. A low-pressure air mass usually dominates the Arctic, while higher pressure air sits over the mid-latitudes. This pressure difference generates winds that confine extremely cold air to the Arctic. Sometimes, the pressure systems weaken, decreasing the pressure difference between the Arctic and mid-latitudes and allowing chilly Arctic air to slide south while warmer air creeps north. A weaker-than-normal Arctic Oscillation is said to be negative. When the pressure systems are strong, the Arctic Oscillation is positive.” Source: NASA Earth Observatory
I've put together some plots from 25th Nov to Dec 8th 2010 showing how this can influence our weather.
Looking at the 500mb anomaly plot for the last couple of weeks we can see a prime example of a strong CLASSIC Greenland blocking high that opened the siberian door.
In the below chart i look at the surface air temperature anomaly during the last couple of weeks.We clearly see the core of the cold originating from Siberia and spreading across europe carried in those easterly winds, to give us a most memorable late November/early December 2010.
We see that during this period as a whole the AO(Arctic Oscillation)Index took a nose dive.(12/10/2010) means up to date as of DEC 10th 2010.
So now we look to what might be staring us in the face?
Well the same AO according to model influence is forecast to drop like a stone again.
And according to models at this present time all roads point to another period of exceptionally cold weather approaching.
It should be mentioned that this does not always mean a cold snap is approaching Ireland because of height rises positioning however it is a very good indicator that bitterly cold Polar air is lurking nearby.0 -
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This is a winter forecast view from an Italian website,so excuse the translated mess.
WINTER 2010/2011
The main indexes in modular configurations of the season just begun will be: nina strong, the QBO went from negative to positive during the fall, the 2nd lowest minimum Arctic summer ever (which tends to force an AO-), the Atlantic tripole still very active, high snowcover on the European sector, and last but not least the low solar activity that we drag behind for the past four winters.
Curiously, from 2006/07, the beginning of the period of profound quiet, winters have a way to cool off and configurations have become gradually more and more surprising.
But back to this winter, one of the main differences that characterize this season, unlike the past, will be the largest wave of the jet and then last year will see a different block Atlantic often large and powerful as it is rarely seen in recent times. The first cast will tend to have quite a way west, but later we may see a Orientalisation the same which will alternate source of both the Arctic Seas to the Arctic continental. The European snowcover will help to maintain and transform them into magnets for more waves with about the same as the previous target. For clarity, I would say go and see the possible development month by month ...
December 2010:
In the coming days on the polar vortex will undergo a re-consolidation (AO always negative) but that will be immediately blocked by a comeback in contemporary Atlantic to Aleutians. Meanwhile a group Arctic maritime isolate continental character taking on Eastern Europe due to the presence of snow on the ground to trigger the phenomenon of inversion.
This core is pushed in the form of cold retrograde drop into northern Italy or, at most, slightly north of the Alps. The trend is similar to that of 13 December 2001 or February 6, 1991 but with a little heat 'higher. Immediately after the two high pressure en route to the Arctic will create a bridge linking the Atlantic to the Pacific, bringing perhaps the AO scale values of the scale ... (below -6). The Atlantic side of the block could be truly magnificent and will, perhaps helped by the MJO in step 5, to maintain a negative NAO is not too strong. Hence the split of the lobe derived from the Siberian VP will head to Europe in moving away via the cold air to the west. Central Europe will be the most affected area. We shall probably be a bit 'too far south, but the event is likely to come in, I say slowly, in history. And this is just the beginning of winter.
The third decade could see, after the Westernization of the cold and a slight push on with the VP shooting high zonal and HP will move to Scandinavia (MJO phase 6 / 7?) With new interesting scenarios shortly after Christmas. The map below I have tried to draw the layout of the Geopotential although without a real scale, only to illustrate the configuration "media" that might be of interest to us.
January 2011:
The block station in northern Europe would move under a new push antizonale moderate (AO-perhaps with contributions from stratospheric), positioned in the area west of Iceland. Meanwhile nina strong start to press with an attempt to step in AO +, which most likely will fail. This will, after a raid on Europe cold, a slight recovery of the VP in the Canadian zone, enough HP to push the north east. Here's the frost on Europe and the HP retrogredirà tend to bulging at the center of the continent. So we will have a second part of the month and anticyclonic calm, with instability confined to regions exposed to the currents of Balkan origin. The snowcover at that point would be the whole of Europe and high temperatures would lead to very low values by inversion.
February 2011:
Now the winter has already reached levels really good and would begin to subside. In fact, under the pressure of the strong nina HP dominate our area with more and more robust recovery of the VP Canadian, but ... this tremendous difference between the temperatures of the Atlantic and Euro-Siberian frost would be that the flow of heat driven by the Canadian have a long path through north around the UK. It would start another period AO/NAO-.
Concluded, however, I would say one thing: This prediction is the most "optimistic" for freddofili, but by no means the least likely, so I decided to throw myself because now all the indications are that we are about to suffer a winter that could stay together for large (56/85/91) or very large (29/63).
The most important feature would be to be able to satisfy almost all the peninsula. Underlying all of this could play a crucial role at low solar activity that is now revolutionizing the whole normal connective paintings that had until a few years ago. Now the AO fails to break peace with exceptional values, while often the -4 was almost utopian even after MMW. To conclude the discussion on winter I expect a large number of episodes, but not a persistent cold, namely: the negative anomalies are alternated with short transition phases in positivity.
Wanting to open a parenthesis in the long term can not be excluded, NAO and AO watching that 2008 was the beginning of a new climate cycle as has happened in the 80's, only this time you point and will point down.
Given the enormous potential of the winter we will update soon with another article, a split tropospheric accomplished (if done
), Analyzing the possible influences that will start in 2011. 0 -
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