In September 2010, I did a long-range weather forecast for the French Alps based on patterns of previous years, and predicted a cold spell early on and abundant snow based upon a strong La Nina and an NAO+ winter. Although I was correct about a cold start, my prediction for the NAO+ winter did not really arrive when I expected it, and although the UK experienced more snow than average, there was far less snow here in Chamonix than I had anticipated/hoped for.
So, now in October, I thought it would be good time to produce a new prediction for Winter 2011/2012.
We shall look at La Nina, North Atlantic Oscillation, Sun spot activity, and the seasonal forecasts from the Climate Prediction Centre and the Met Office…
The Climate Prediction Centre in North America put out an advisory on the 6th October predicting La Nina conditions to gradually strengthen and continue through the Northern Hemisphere winter 2011/2012.
Here is what they say
“Currently, La Niña is not as strong as it was in September 2010. Roughly one-half of the models predict La Niña to strengthen during the Northern Hemisphere fall and winter. Of these models, the majority predict a weak La Niña (3-month average in the Niño-3.4 region less than -0.9oC). In addition, a weaker second La Niña winter has occurred in three of the five multi-year La Niñas in the historical SST record since 1950. However, the NCEP Climate Forecast System (CFS.v1) predicts a moderate-strength La Niña this winter (between –1.0oC to –1.4oC) and CFS.v2 predicts a strong La Niña (less than –1.5oC), which rivals last year’s peak strength. For CFS forecasts made at this time of year, the average error for December-February is roughly ±0.5oC, so there is uncertainty as to whether this amplitude will be achieved. Thus, at this time, a weak or moderate strength La Niña is most likely during the Northern Hemisphere winter.”
Climatelogic.com wrote last year:
“The effect of La Niña on European winters is different for November-December and January-March periods. In November-December, La Niña events are associated with positive sea-level pressure anomalies in the area between Greenland and Western Europe. This high-pressure center blocks the warm westerly flow from the North Atlantic and temperatures in Europe drop. Later in the winter, however, the atmospheric circulation tends to become more zonal, bringing warm Atlantic air to Europe and reducing the frequency of cold air outbreaks from the north. This coming winter (ed. note: 2010/11), however, even in January-February temperature anomalies may remain negative over much of Europe”.
This was is pretty much what we experienced last year as the UK experienced a very cold winter, and it was colder than normal here in the Alps until the end of mid-Winter (DJF) when the weather switched and become warmer than usual during early Spring (FMA).
The El Nino / La Nina event also appears to experience a sea surface temperature variation trend of an approximate 60-year cycle.
As you can see it is about to enter its negative phase.
The Pacific Decadal Oscillation
The Pacific Decadal Oscillation (PDO) is a pattern of Pacific climate variability off the West coast of America which operates on a 20-30 year cycle. During a negative phase, the west Pacific warms and the east Pacific (ie off the West coast of America) cools. From the mean line on the graph below it looks as though this oscillation will be heading into the negative phase of its cycle soon.
The PDO differs from the El Nino/La Nina cycles which persist for only 6-18 month. As global temperatures are tied directly to sea surface temperatures when sea surface temperatures cool (as from 1945 to 1977), global climate cools. This is sometime which may affect the underlying patterns for the next couple of decades.
Atlantic Multi-Decadal Oscillation
It should be noted that the Atlantic also experiences multi-decadal warm and cool periods of about 30 years, much like the PDO. During warm phases, the Atlantic is warm in the tropical North Atlantic and far North Atlantic and relatively cool in the central area. During cool phases, the tropical and far North Atlantic are cool and the central ocean is warm.
The cycle length is approximately 62 years.
The North Atlantic Oscillation
“Strong positive phases of the NAO tend to be associated with above-average temperatures in the eastern United States and across northern Europe and below-average temperatures in Greenland and oftentimes across southern Europe and the Middle East. They are also associated with above-average precipitation over northern Europe and Scandinavia in winter, and below-average precipitation over southern and central Europe. Opposite patterns of temperature and precipitation anomalies are typically observed during strong negative phases of the NAO.”
If you look at the graph above, it might appear to show that we are experiencing a strong NAO- condition at the moment. However, the graph below shows that this has in fact shifted into a weak NAO+ condition since mid-August, and is forecast to return to a predominantly NAO- pattern in the next couple of weeks.
However, something interesting appears if you look at the standardised seasonal mean for January/February/March……
This graph is very interesting as it shows the standardized seasonal mean NAO index during the cold season (blue line) which is constructed by averaging the daily NAO index for January, February and March for each year. The black line denotes the standardized five-year running mean of the index. Both curves are standardized using 1950-2000 base period statistics.
You can clearly see a 60 year cycle pattern.
From this alone, one might expect the weather for the next few winters to have a predominantly negative NAO and thus to have certain similarities to weather in the 1950’s when the winter temperatures were slightly colder than average, and experienced a number of extra cold events in 1950, 1953, 1954, 1957. Most notably early February 1956 when temperatures were between -8.6 and -10° colder than average for those same dates.
Unfortunately for skiers, there is no correlation between the amount of precipitation and the North Atlantic Oscillation, so we cannot use this to predict snow levels.
So what’s going on with all these 60 year cycles?
Influence of Solar Orbit on Global Weather Patterns ?
Nicola Scafetta has identified the change in the location of the centre of mass of the solar system (CMSS) as a possible mechanism driving the 60-year cycle. Jupiter has the largest mass of any planet and is thus most influential with a solar orbital cycle of 11.9 Earth years. Saturn, the second-largest planet, has a solar orbital cycle of 29.4 Earth years. This leads to Jupiter-Saturn conjunction every 19.9 years. A fully cycle of Jupiter /Saturn around the sun is 59.6 years. In other words, it takes approximately 60 years for the Earth / Jupiter / Saturn to reach the same relative alignment around the Sun – and this causes cyclical changes in the centre of mass of the solar system.
The following figure shows the speed of the Sun relative to the CMSS showing “20 and 60 year oscillations”. It shows a 60-year cycle with peaks similar to the global average temperatures peaks – around 1880, 1940 and 2000
Scafetta postulates here that
The physical mechanisms that would explain this result are still unknown. Perhaps the four jovian planets modulate solar activity via gravitational and magnetic forces that cause tidal and angular momentum stresses on the Sun and its heliosphere. Then, a varying Sun modulates climate, which amplifies the effects of the solar input through several feedback mechanisms. This phenomenon is mostly regulated by Jupiter and Saturn, plus some important contribution from Neptune and Uranus.
Alternatively, the planets are directly influencing the Earth’s climate by modulating the orbital parameters of the Earth-Moon system and of the Earth. Orbital parameters can modulate the Earth’s angular momentum via gravitational tides and magnetic forces. Then, these orbital oscillations are amplified by the climate system through synchronization of its natural oscillators. This interpretation is supported by the fact that the temperature records contain a clear 9.1-year cycle, which is associated to some long-term lunar tidal cycles.
Now, let’s talk about sunspots which have an 11 year cycle.
Early records of sunspots indicate that the Sun went through a period of inactivity in the late 17th century. Very few sunspots were seen on the Sun from about 1645 to 1715. This period of solar inactivity, known as the Maunder Minimum, also corresponds to a climatic period called the “Little Ice Age” when rivers that are normally ice-free froze and snow fields remained year-round at lower altitudes. There was also a period (Dalton minimum) lasting from about 1790 to 1830 which coincides with a period of lower-than-average global temperatures.
So, extremely low sunspot activity appears to correlate to cold climatic periods.
Sunspot info: http://solarscience.msfc.nasa.gov/SunspotCycle.shtml
So what is going on currently? Although the number of sunspots is rising from its minimum in 2009, it would appear from this prediction that we are entering a period of reduced sunspot activity for the next cycle.
Some unusual solar readings, including fading sunspots and weakening magnetic activity near the poles, could be indications that our sun is preparing to be less active in the coming years.
The results of three separate studies seem to show that even as the current sunspot cycle swells toward the solar maximum, the sun could be heading into a more-dormant period, with activity during the next 11-year sunspot cycle greatly reduced or even eliminated.
The results of the new studies were announced today (June 14) at the annual meeting of the solar physics division of the American Astronomical Society, which is being held this week at New Mexico State University in Las Cruces.
This might result in weather with below-average temperature for the next few years or even decades.
Overall Long Term
So, given that we are entering the periods of negative phase ENSO, negative phase NAO trend, with a low sunspot activity forecast, I think we could possibly experience a period of lower than average temperatures in the future. A few climatologists seem to hold that view of a cooler future. Look up Nils-Axel Morner, James Madden , (or Piers Corbyn if you fancy watching/reading something controversial…).
So, what about the French Alps, Chamonix and this coming Winter….
I want you to look at the following two seasonal chart predictions from the Climate Prediction Centre:
The chart above appears to show a normal temperature prediction throughout most of Europe for the entire winter (Scandinavia being slightly warmer than average late season). Colder than average appears in blue.
The chart above would predict a drier than normal winter (except Scandinavia late season).
So the CFS predicts a winter with average temperatures that is drier than normal.
However, the Met Office put this out which would appear to predict an above-average chance of a cold Nov/Dec/Jan period across the French Alps.
The Met Office charts would also appear to show that we should expect near normal levels of precipitation during Dec/Jan/Feb…
Combining the two predictions from the Met, below average temperatures and normal precipitation would be good news for skiers in the French Alps! (of course, I am sure that all us skiers would prefer mildly below average temperatures and above average precipitation…. ).
Not every meteorologist agrees with either the CFS or Met Office forecasts:
James Madden from Exacta says
“Based on the natural factors that I have covered and in terms of how I calculate solar activity into my forecasts, it would be adequate to suggest prolonged periods of well below average temperatures and widespread heavy snowfall throughout this winter. This will result in the fourth bad winter in succession for the UK, and will prove to be the worst of them all.”
Yves Durand et al write in their “Reanalysis of 44 yr of climate in the French Alps (1958-2002)” that
“Looking at snow precipitation trends in the light of temperature trends reveals that in the north, falling temperatures are associated with slightly rising snowfalls (early winter)”.
“The SAFRAN 2-m air temperature and precipitation climatology shows that the climate of the French Alps is temperate and is mainly determined by atmospheric westerly flow conditions. Vertical profiles of temperature and precipitation averaged over the whole period for altitudes up to 3000 m MSL show a relatively linear variation with altitude for different mountain areas with no constraint of that kind imposed by the analysis scheme itself. Over the observation period 1958–2002, the overall trend corresponds to an increase in the annual near-surface air temperature of about 1°C. However, variations are large at different altitudes and for different seasons and regions. This significantly positive trend is most obvious in the 1500–2000-m MSL altitude range, especially in the northwest regions, and exhibits a significant relationship with the North Atlantic Oscillation index over long periods. Precipitation data are diverse, making it hard to identify clear trends within the high year-to-year variability”.
So basically the NAO correlates better with temperature than precipitation, especially in the North West Alps.
From “Mountain climates and climatic change: An overview of processes focusing on the European Alps “, Martin Beniston writes
“When computed for 1901-1999, 56% of the observed pressure variance in Switzerland can be explained by the behaviour of the NAO. From 1961-1999, this figure rises to 83%, which is considerable bearing in mind the numerous factors that can also determine regional pressure fields. As for pressure trends, the synchronous behaviour between temperature and the NAO is striking, particularly in the second half of the 20th Century.
A particular feature of the positive phase of the NAO index is that it is invariably coupled to anomalously low precipitation and milder than average temperatures, particularly from late fall to early spring, in southern and central Europe (including the Alps and the Carpathians), while the reverse is true for periods when the NAO index is negative.
Since the early 1970s, and until 1996, the wintertime NAO index has been increasingly positive, indicative of enhanced westerly flow over the North Atlantic. Over the Alpine region, positive NAO indices have resulted in surface pressure fields that have been higher than at any time this century”.
The study has confirmed other findings that snow in the Alps is highly variable from year to year, but that there are some long-term cycles which appear to be governed by shifts in large-scale forcings. These are represented by the North Atlantic Oscillation index, whose influence extends to the Alps when the index is positive and high; the pressure signal from the NAO index is amplified in the Alpine region. Over the last 15 years, which saw a number of cold winters accompanied by significant amounts of snow, followed since the second half of the 1980s by some very mild winters with little snow, the dominant feature has been the variations of the regional-scale pressure field
In “Variations of snow depth and duration in the Swiss Alps over the last 50 years: links to changes in large-scale climatic forcings”, Martin Beniston writes,
“Periods with relative low snow amounts and duration are closely linked to the presence of persistent high surface pressure fields over the Alpine region during late Fall and in Winter. These high pressure episodes are accompanied by large positive temperature anomalies and low precipitation, both of which are unfavourable for snow accumulation during the Winter. The fluctuations of seasonal to annual pressure in the Alpine region is strongly correlated with anomalies of the North Atlantic Oscillation index, which is a measure of the strength of the westerly flow over the Atlantic.
Furthermore, since the mid-1980s, the length of the snow season and snow amount have substantially decreased, as a result of pressure fields over the Alps which have been far higher and more persistent than at any other time this century. A detailed analysis of a number of additional Alpine stations for the last 15 years shows that the sensitivity of the snow-pack to climatic fluctuations diminishes above 1750 m.
So basically the higher you go, the less climatic fluctuations play a part on the snow pack.
That makes sense as the higher you go, the more likely it is that any precipitation will fall as snow.
Also, higher pressure seems to link to reduced snowfall, and therefore low pressure means higher snowfall…
So, let’s take a look at the CFS pressure forecast….
So let’s put it all together and take a gamble on what I think is going to happen…
This year, I predict that overall the pattern will be quite similar to last year with a colder than normal start to October/November. We have just had snow down to 1000m in Chamonix this weekend which fits nicely.
I think we will experience a moderate to strong La Nina and weak NAO- conditions for November and December, changing to stronger NAO- conditions for January, February and March.
As it will not be a strong NAO+, it is harder to predict how the winter might be.
However, I am thinking we will have a cold November with average amounts of precipitation – which hopefully will mean the ground will freeze early and that any precipitation will come as snow here in the Alps. This means the winter season may be earlier coming on, and would bode well for a good start to the ski season.
If there is low pressure as predicted by the CFS, then that could bode well for snow falls in Jan/Feb/Mar, and although the NAO- tends to mean higher precipitation further south, I think Chamonix will fair well and there will be a reasonable to good snow fall in Jan/Feb/March. I think this will however be followed by a relatively early spring. So if you are planning late season skiing at Easter, then choose somewhere nice and high like Tignes, Val d’Isere, or Chamonix where the skiing goes from 1000m to 3842m.
Interesting reads :
Variations of snow depth and duration in the Swiss Alps over the last 50 years: Links to changes in large-scale climatic forcings” Martin Beniston, Institute of Geography, University of Fribourg, Switzerland.
Reanalysis of 47 Years of Climate in the French Alps (1958–2005): Climatology and Trends for Snow Cover Yves Durand, Gérald Giraud, Martin Laternser, Pierre Etchevers, Laurent Mérindol, Bernard Lesaffre. (2009) . Journal of Applied Meteorology and Climatology
Mountain climates and climatic change: An overview of processes focusing on the European Alps. BENISTON M. Pure and Applied Geophysics, 2005, Vol. 162, p. 1587-1606.
The Sixty-Year Climate Cycle
Source : http://www.appinsys.com/globalwarming/SixtyYearCycle.htm
Arctic Environment by the Middle of this Century. Nils-Axel Morner (2011) Energy & Environment, 2011, Vol 22, No 3.
The solar Influence on the probability of relatively cold UK winters in the future” Lockwood, M. et al, “2011, Environmental Research Letters.
Source : http://iopscience.iop.org/1748-9326/6/3/034004/pdf/1748-9326_6_3_034004.pdf