Winter 2010-2011 outlook

nacho libre

M.T. Cranium wrote: »

When that high was based on Lempfert, did he get up again later?

That's probably the highest pressure seen in modern times over Europe, and yet nobody ever mentions 1907 as one of the great winters. I guess it didn't do too much more than shunt some cold air west.

In this discussion, it's interesting that we all tend towards a default position where the whole winter conforms to some general pattern. Some winters (even in the European climate) have a mid-season reversal and I have a hunch that this winter might be like that (cold first half, mild second half).

If the reversal comes late enough as in Feb 2005, then the winter is remembered mostly for the first longer segment, even if the second shorter segment is the more significant in terms of impacts.

With my research partner in crime (known as Blast from the Past on the net-weather forum) we are hoping to finalize a forecast soon, but I have to be quite frank, this season has mixed signals and the La Nina pattern is shaping up very strong over North America here, which has got to be factored into the final result -- if we have a screaming fast flow here and there is no major blocking in the Atlantic, then that fast flow is going to reach Europe sooner or later, and usually fast flow drives the jet higher.

So if you're hoping for wintry weather, I think it had better come in December before the window of opportunity is shut.

this seems to correspond with what Stewart Rampling predicts. The only difference between ye seems to be in the timing; he indicates a reversal to milder setup going into February. I wonder is the difference in the timing down to him being of the view that the mid latitude blocking will be fairly potent?

eskimocat

I was wondering how or if Ireland's infamous 'shield' comes into play with all of this??

What causes this shield? I remember that during the snow spell that it repelled quite a few possible snow showers.

Thanks

Iancar29

Jerry Seinfeld wrote: »

That's Norway!

....FAIL.... haha

Correction so, I WANNA GO BACK TO NORWAY!!

Min

eskimocat wrote: »

I was wondering how or if Ireland's infamous 'shield' comes into play with all of this??

What causes this shield? I remember that during the snow spell that it repelled quite a few possible snow showers.

Thanks

The shield is caused by the old people praying as they are afraid of falling and breaking something on the ice and snow...

nacho libre

eskimocat wrote: »

I was wondering how or if Ireland's infamous 'shield' comes into play with all of this??

What causes this shield? I remember that during the snow spell that it repelled quite a few possible snow showers.

Thanks

in the setup we had last year, for the most part you were in the worse possible location to get snow- unless it was frontal snow. which is what happened around the middle of January. A lot of the west and parts of the northwest got snow then, did you?

Dyflin

Dyflin wrote: »

Bergen (Norway), as far north as the Shetlands, woke up to this weather this morning




Bone dry yesterday :rolleyes:

Actually, just read that it's their earliest snow since 1973, talk about rubbing salt in the wound!

Woops, now where did I put those winter tyres.

Graces7

Min wrote: »

The shield is caused by the old people praying as they are afraid of falling and breaking something on the ice and snow...

Nice one Min!!

Not just the old ones either..;)

Hoping for a better ie snow-less winter here. Although we have had frost already.

Graces7

Graces7 wrote: »

Nice one Min!!

Not just the old ones either..;)

Hoping for a better ie snow-less winter here. Although we have had frost already.

You can those of us who don't want big fuel bills to the list.

Iancar29

Phanthom 105.2 are gonna be talking about the chances of a white christmas in the next while!

Probably a certain donegal postman will be involved!

Speak Now

Iancar29 wrote: »

Phanthom 105.2 are gonna be talking about the chances of a white christmas in the next while!

Probably a certain donegal postman will be involved!

probably sponsored by paddy power

Popoutman

I'd love a winter where there are clear nights, with little to no cloud and great transparency. I'd also like to have only gentle ground-level winds, and preferably with no great windspeeds at altitude, mixing up the seeing. I don't mind if it's cold, as long as it's a relatively dry cold as I can work with that.

Us astronomers need clear steady air and no cloud to be able to see some things at their best, and it's so rare in this country to get it right often...
If it's clear, it's usually got really bad seeing and the stars appear as at the bottom of a fast flowing stream. If it's steady, it's usually either cloudy or there is enough haze that any galaxies are invisible against the brighter sky background..

Looks as though this winter is not shaping up to be anything different!

snowstreams

Last winter must have been good for astronomy though cause of the low humidity and not too much wind?
Ive always noticed that a good cold winters day gives the best visibility to places like wales from ireland. Maybe thats not what you need for looking at stars though?

Redsunset

NAO acting on Gulf stream

Where the pressure gradient is shallow, the index number is negative, and is manifested by weaker winds and storm systems in the North Atlantic. The result is less forward forcing of the Gulf Stream by the south-westerly winds.

Where the pressure gradient is steep, the index number is positive, and is manifested by more frequent and more intense storms, stronger south-westerly winds, and thus more forward forcing of the Gulf Stream.

Herein lies the key to why sea ice thickness in the Arctic might be subject to variation unrelated to atmospheric temperature. A stronger faster Gulf Stream driven by a positive NAO, enters the Arctic, retaining more of its warmth due to the faster trans-Atlantic passage of the Gulf Stream waters, and increases the rate of summer ice melt from beneath the ice. When the NAO is negative, the Gulf Stream is both weaker and slower, has cooled more by the time it does reach the Arctic - and the ice gets thicker in consequence.
QUOTE

---

The above text might explain to a degree any slowing lately of the Gulf stream which there has been some talk about.

---

Effect of solar activity



A substantial portion of the climate variability in the Atlantic sector is associated with the North Atlantic Oscillation (NAO), with variations occurring on a wide range of scales. The influence of solar activity (expressed by various indices) on the NAO has been studied by a number of authors. Having reviewed the information available to him, Lamb (1972, p. 252) noticed several tendencies in the surface parameters in relation to solar activity. These tendencies included:

• Strong development of the mid-latitude westerlies, Icelandic low and Azores high around the middle of the declining phase of solar activity;
• Strong meridional and cellular circulation systems at some stage during the more rapid rises of solar disturbance and greatest frequency of very strong anomalies of pressure and temperature (intense systems);
• Also (perhaps later) during the ascent, a phase of strong middle latitudes westerlies, strong Icelandic low and Azores high, seems particularly liable to occur.

More recently, Bucha and Bucha (1998) found a correlation between geomagnetic activity and sea level pressure variations similar to the NAO for the period 1970 to 1996. They suggested a mechanism based on winds generated in the polar thermosphere following geomagnetic storms.

Bochnicek and Hejda (2005) demonstrated that during the winter periods (January–March) of the years 1963–2001 high geomagnetic activity was nearly always associated with a positive phase of the NAO, whereas low geomagnetic activity tended to couple with the negative phase. Palamara and Bryant (2004) and Fujita and Tanaka (2007) found a similar relationship with the Northern Annular Mode (NAM). According to Thejll et al. (2003), who studied the relationship between the geomagnetic index Ap and the NAO for the period 1949-2000, the correlation was high and significant only since about 1972.



However, for the period 1949–1972 no significant correlations were found at the surface while significant correlations still existed in the stratosphere. This might indicate that the solar forcing, primarily acting in the stratosphere, is propagating its influence downward in the later period but not in the earlier.

A robust relationship between solar cycle variations, proxied by the 10.7 cm solar radio flux, and the NAM has been found by Ruzmaikin and Feynman (2002). In particular, the NAM index was found to be systematically more negative (corresponding to a weaker polar jet) during low solar activity (Ruzmaikin et al., 2004).


Kodera (2002, 2003) showed that the spatial structure of the NAO varies significantly according to the phase of the solar cycle. During solar maximum phases, the NAO covers the Northern Hemisphere and extends into the stratosphere, which is similar to the Arctic Oscillation (AO) (Thompson and Wallace, 1998), except for the Pacific sector. By contrast, for minimum solar phases, the NAO is confined to the Atlantic sector and to the troposphere.

Boberg and Lundstedt (2002, 2003) showed that variations of the NAO index could be correlated with the electric field strength of the solar wind. Using geopotential height data they found a strong correlation between the electric field strength of the solar wind and pressure variations in the stratosphere and troposphere. For the tropospheric pressure the influence is confined to the North Atlantic and resembles the action of the NAO.

On a secular time scale, Kirov and Georgieva (2002) found a negative correlation between the NAO index and sunspot activity: the index had a maximum during the period of low solar activity in the late 19th and early 20th century and a minimum during the period of high solar activity in the 1950s and 1960s.

However, since the data covers only one secular cycle, their conclusion is not statistically sound. In their later work, addressing the issue of instability in solar terrestrial relationships, Georgieva et al. (2007) underscored the importance of asymmetry between sunspot numbers in the northern and southern solar hemispheres.

They hypothesize that when the southern solar hemisphere is more active, increasing solar activity in the secular solar cycle leads to strengthening of the zonal atmospheric circulation, and when the northern solar hemisphere is more active, increasing solar activity in the secular solar cycle leads to weakening of the zonal circulation.

There are also a number of works that have examined the effect of solar activity on climatic variables other than the NAO (but often closely related to the NAO). Here, for brevity, we will mention just one of those works, because it underscores the importance of the 22-year Hale cycle, which manifests itself in reversal of polarity of sunspots from one 11-year cycle to another.

According to Bochkov (1978), during even cycles of solar activity and on its ascending branch, the Barents Sea is characterized by suppressed cyclonic activity, negative anomalies of sea and air temperature and increased ice cover. In contrast, during the decreasing branch of solar activity (2-5 years after its maximum), the Barents Sea tends to be warmer than normal. The situation during the odd cycles of solar activity is less clear.


Fig. 1. The winter (DJF) NAO index from CPC, 1951-2008.

Despite the complexity of solar effect on North Atlantic climate, most of the authors seem to agree that negative (positive) NAO phases tend to occur during low (high) levels of solar activity. This simplified relationship refers to both the 11-year and secular solar cycles.
Currently, the solar activity is at the beginning of its 24th cycle. Also, it seems to be on a declining phase of the secular cycle, but still remains relatively high. The behaviour of the NAO ([URL="file:///C:/Documents%20and%20Settings/Sergei/My%20Documents/ClimateLogic/WebSite/pub/STTA/NAO.png"]Fig. 1[/URL]) and AO ([URL="file:///C:/Documents%20and%20Settings/Sergei/My%20Documents/ClimateLogic/WebSite/pub/STTA/AO.png"]Fig. 2[/URL]) indices in recent decades seem to be consistent with the above relationship: both indices reached their maximum values in the early 1990s and now tend to stay close to their average values.



Fig. 2. The winter (DJF) AO index from CPC, 1951-2008.

As the 24th solar cycle progresses, entering into its ascending phase, one can expect a weakening of the subpolar low and developing of a meridional type of atmospheric circulation, with an increasing frequency of the negative NAO.

Closer to the maximum of solar activity, and on the descending branch of the cycle, zonal atmospheric circulation (positive NAO) may become prevalent again.

Much will depend on whether the 24th cycle will be weak or strong. If it is going to be a weak cycle (which is somewhat more likely), the NAO may become strongly negative, resulting in a substantial cooling in the Northeast Atlantic, Norwegian and Barents Seas.



This Solar info is same as posted in Sun is dead thread

WolfeIRE

europe will warm up gradually over the next two weeks

Kippure

Cabon copy as last year WolfeIRE, then we all know what happened next!

Pangea

M.T. Cranium wrote: »

So if you're hoping for wintry weather, I think it had better come in December before the window of opportunity is shut.

I dont buy into long term scientific predictions and cycles.
Its a long winter anything can happen.
No one saw last years cold snap even happening or lasting so long.

M.T. Cranium

There were several predictions of a cold snap last winter and some of these even mentioned late December and January. When we try to validate verbal forecasts it becomes more subjective than numerical forecasts.

Anyway, to illustrate both the strong and weak points of existing LRF capability, I dug up my own outlook for last winter which you can verify was posted on 7 November 2009 in the forecast thread.

This is what it said:

---

Following is my Winter Outlook for Ireland

On the whole, I expect this to be a slightly colder than average winter in Ireland, with some very cold periods in mid to late December and in parts of mid-January as well. Milder periods will occur in early December, around new years, and from the end of January through much of February.

In the colder periods, some lying snow is possible. There may be one or two days with snow in later November, then look for a better chance in the week before Christmas, and a very good chance for snow from about the 10th of January to 25th of January, not necessarily all through that period, but perhaps on more than one occasion during it.

Some of the milder days may be accompanied by heavy rains and high winds. During the expected mild spell in early December, I think the storm track will at first run well north of Ireland but if not, strong winds could be expected around the 2nd and 5th. Later on, towards the 15th, there would be a good chance of a strong wind event as the milder spell transitions to the expected colder weather.

Another time to look for strong winds would be around New Years Eve and Day when I expect a strong low to be present somewhere near northern parts of Ireland and western Scotland.

A period around 14-15 January may be stormy with mixed or snowy precipitation as well as strong winds. Then towards the end of January, there may be very strong winds and rain with a return to milder conditions.

February by contrast may be a rather bland month, especially if it doesn't snow in the first few days like last year. I believe that January will be the best "winter" month in the winter of 2009-10.

---

There is a clear indication in that forecast of cold (it mentions very cold) weather in late December and much of January. Where the forecast was somewhat in error was to mention a milder turn at New Years between two parts of a longer cold snap -- this is what the guidance being used had indicated, and the milder turn came a few days earlier than New Years and quickly disappeared during 31 Dec into 1 Jan (as I recall the low that was predicted at that time took a meandering track towards Ireland, circled around and went into France). Then I consider it to be related in conceptual terms that the snow in January came mostly before the period cited, although not entirely, some snow was reported as late as the 15th. Even using the methodology in question, some accuracy was lost there through careless choice of words rather than poor model performance (the trend lines fell below freezing before the 10th but yours truly was more focused on the mid-month potential from energy level as opposed to temperature input).

However, all things considered, the above is probably better than a random shot in the dark (don't forget it was very mild and the Atlantic was raging when this forecast was issued) and that's about all one could expect from the current state of development of this "far end" of weather forecasting. I mean, it stands to reason that if the five day forecast is still only moderately reliable, then seasonal trend forecasting will have to work very hard to beat random chance. So I'm under no illusions about difficulty, but that forecast was accepted by most as being more accurate than not (about the same forecast was made for readers on UK weather forums and it got the same mixed responses, the thing being, if we just wait for a perfect forecast model to emerge, we might be waiting forever, this field is likely to see incremental advances and not spectacular breakthroughs).

Other forecasts issued for last winter may have been better or worse than this one, I don't have much specific recall now, but I seem to remember the net-weather official forecast calling for below normal temperatures which verified. As to this coming winter, I am still thinking about it, strikes me as a tougher call than the past two.

Pangea

You did indeed predict the very cold parts of late December and January correctly so well done MT.
I am not knocking your methods ,just saying that I personally dont like to look too dip into the analyisis of long term forecasts or patterns, as I said anything can happen

derekon

M.T. Cranium wrote: »

There were several predictions of a cold snap last winter and some of these even mentioned late December and January. When we try to validate verbal forecasts it becomes more subjective than numerical forecasts.

Anyway, to illustrate both the strong and weak points of existing LRF capability, I dug up my own outlook for last winter which you can verify was posted on 7 November 2009 in the forecast thread.

This is what it said:

---

Following is my Winter Outlook for Ireland

On the whole, I expect this to be a slightly colder than average winter in Ireland, with some very cold periods in mid to late December and in parts of mid-January as well. Milder periods will occur in early December, around new years, and from the end of January through much of February.

In the colder periods, some lying snow is possible. There may be one or two days with snow in later November, then look for a better chance in the week before Christmas, and a very good chance for snow from about the 10th of January to 25th of January, not necessarily all through that period, but perhaps on more than one occasion during it.

Some of the milder days may be accompanied by heavy rains and high winds. During the expected mild spell in early December, I think the storm track will at first run well north of Ireland but if not, strong winds could be expected around the 2nd and 5th. Later on, towards the 15th, there would be a good chance of a strong wind event as the milder spell transitions to the expected colder weather.

Another time to look for strong winds would be around New Years Eve and Day when I expect a strong low to be present somewhere near northern parts of Ireland and western Scotland.

A period around 14-15 January may be stormy with mixed or snowy precipitation as well as strong winds. Then towards the end of January, there may be very strong winds and rain with a return to milder conditions.

February by contrast may be a rather bland month, especially if it doesn't snow in the first few days like last year. I believe that January will be the best "winter" month in the winter of 2009-10.

---

There is a clear indication in that forecast of cold (it mentions very cold) weather in late December and much of January. Where the forecast was somewhat in error was to mention a milder turn at New Years between two parts of a longer cold snap -- this is what the guidance being used had indicated, and the milder turn came a few days earlier than New Years and quickly disappeared during 31 Dec into 1 Jan (as I recall the low that was predicted at that time took a meandering track towards Ireland, circled around and went into France). Then I consider it to be related in conceptual terms that the snow in January came mostly before the period cited, although not entirely, some snow was reported as late as the 15th. Even using the methodology in question, some accuracy was lost there through careless choice of words rather than poor model performance (the trend lines fell below freezing before the 10th but yours truly was more focused on the mid-month potential from energy level as opposed to temperature input).

However, all things considered, the above is probably better than a random shot in the dark (don't forget it was very mild and the Atlantic was raging when this forecast was issued) and that's about all one could expect from the current state of development of this "far end" of weather forecasting. I mean, it stands to reason that if the five day forecast is still only moderately reliable, then seasonal trend forecasting will have to work very hard to beat random chance. So I'm under no illusions about difficulty, but that forecast was accepted by most as being more accurate than not (about the same forecast was made for readers on UK weather forums and it got the same mixed responses, the thing being, if we just wait for a perfect forecast model to emerge, we might be waiting forever, this field is likely to see incremental advances and not spectacular breakthroughs).

Other forecasts issued for last winter may have been better or worse than this one, I don't have much specific recall now, but I seem to remember the net-weather official forecast calling for below normal temperatures which verified. As to this coming winter, I am still thinking about it, strikes me as a tougher call than the past two.

Thanks for that MT along with your daily forecasts (love your updates too about weather in Canada!)

When do you hope to issue your winter forecast for Ireland for winter 2010/2011 ?

Derek

km79

Kippure wrote: »

Cabon copy as last year WolfeIRE, then we all know what happened next!

do you mean the floods or big freeze?

eskimocat

nacho libre wrote: »

in the setup we had last year, for the most part you were in the worse possible location to get snow- unless it was frontal snow. which is what happened around the middle of January. A lot of the west and parts of the northwest got snow then, did you?

We had a few days of snow, but yes, it was a little while after the first falls...had mostly ice, and thick thick ice it was too!! some hail and plenty of sleet.

M.T. Cranium

Thanks, Derek, I do a forecast each winter with another guy who posts on net-weather, and we haven't had chance to nail down a prediction yet, but I think mid-November may be about when we will take the plunge.

This may be the toughest forecast challenge in a while given conflicting signals, so it might actually make a lot of sense to predict a little of everything although that would probably be seen as a hedged forecast unless you could supply an accurate calendar of what was going happen when ... and in some sort of mixed up pattern of all kinds of weather, that would be truly Ring-like even to attempt it.

When it is finalized (a preliminary version has already been posted) I will either post it here or link to it here on this thread. Then you'll know what not to expect.

Kippure

km79 wrote: »

do you mean the floods or big freeze?

Both, What we are seeing in the models now is a carbon copy of last years pressure patten imo.

derekon

M.T. Cranium wrote: »

Thanks, Derek, I do a forecast each winter with another guy who posts on net-weather, and we haven't had chance to nail down a prediction yet, but I think mid-November may be about when we will take the plunge.

This may be the toughest forecast challenge in a while given conflicting signals, so it might actually make a lot of sense to predict a little of everything although that would probably be seen as a hedged forecast unless you could supply an accurate calendar of what was going happen when ... and in some sort of mixed up pattern of all kinds of weather, that would be truly Ring-like even to attempt it.

When it is finalized (a preliminary version has already been posted) I will either post it here or link to it here on this thread. Then you'll know what not to expect.

Thanks MT - will look forward to your forecast. This forum is great for learning about weather, learning lots from your posts and others who post here..!

Derek

WolfeIRE

while normal temps (for the time of year) will kick in from monday until the end of the first week of november (according to model outputs) it must be said that the signs are good for the coming winter.

keep an eye on the following
http://www.meteociel.fr/modeles/gefs_cartes.php?ech=0&code=0&mode=1&runpara=0
http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=0&map=0&type=0&archive=0

track how the warmer upper atmosphere temps are skirting around ireland. this trend has been ongoing since the middle of september, with the exception of brief milder interlude 10 days ago. The prospect of normal or slightly below winter temps, broken up by brief milder spells, bodes well for the coming winter as such a scenario would deliver more snowfall i.e. entrenched cold meeting atlantic fronts.

I know Su said that the seas around greenland and scandanavia are warmer than they were last year, thus reducing the severity of any northerly or northeasterlies on ireland. However, should the current set up continue my guess is that we will see the heaviest snow this winter affect the western half of the island as atlantic fronts come up against colder air entrenched over ireland (similar to march 2010).

the nao has shifted the influence of the jet stream further south as far as my woefully untrained eye can see and this bodes well.

This is my observation for what it is worth. I guess it's my prediction for the coming winter.

Graces7

Deleted User wrote: »

You can those of us who don't want big fuel bills to the list.

Yep.... as in cannot afford fuel also. Bord Gais are threatening wholesale disconnections as folk are still in debt from last winter. Here, they had to fell a tree so we have some wood and we are saving it for bad days.

WolfeIRE

http://www.usatoday.com/weather/climate/2010-10-21-winter-outlook_N.htm?

US Winter outlook

thetonynator

WolfeIRE wrote: »

while normal temps (for the time of year) will kick in from monday until the end of the first week of november (according to model outputs) it must be said that the signs are good for the coming winter.

keep an eye on the following
http://www.meteociel.fr/modeles/gefs_cartes.php?ech=0&code=0&mode=1&runpara=0
http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=0&map=0&type=0&archive=0

track how the warmer upper atmosphere temps are skirting around ireland. this trend has been ongoing since the middle of september, with the exception of brief milder interlude 10 days ago. The prospect of normal or slightly below winter temps, broken up by brief milder spells, bodes well for the coming winter as such a scenario would deliver more snowfall i.e. entrenched cold meeting atlantic fronts.

I know Su said that the seas around greenland and scandanavia are warmer than they were last year, thus reducing the severity of any northerly or northeasterlies on ireland. However, should the current set up continue my guess is that we will see the heaviest snow this winter affect the western half of the island as atlantic fronts come up against colder air entrenched over ireland (similar to march 2010).

the nao has shifted the influence of the jet stream further south as far as my woefully untrained eye can see and this bodes well.

This is my observation for what it is worth. I guess it's my prediction for the coming winter.

Are you sure thats not just wishful thinking? :P

WolfeIRE

That's my guess based on current trends....

as well as a mixture of

Graces7

WolfeIRE wrote: »

That's my guess based on current trends....

as well as a mixture of

Indeed the latter.... Always!