Good evening and welcome to my first winter post of 2014! In today’s post I will be talking about Eurasian Snow Cover/Advance in October (SAI) and how this correlates to winter, the OPI Index, solar sunspots and some early stratosphere warming!


So, first up I will go to a subject that has been floating around social media and the media in general: The OPI. You may be thinking: what is the OPI? The OPI is short for the October Pattern Index, it is a numerical summary for the northern hemispheric conditions during October! A lot of research has gone into this tool and a really good correlation (when looking back at previous data) has been found! When the OPI is really negative overall, there is a much stronger likelihood that winter will be colder and harsher; this is due to the increased likelihood of a negative AO (probability that cold air will be displaced from the pole).

Screen Shot 2014-10-28 at 18.37.50

If we go ahead and take a look at how the current OPI is shaping up, we can clearly see how negative it is. No bar on that graph has appeared positive during October. That would suggest that a cold winter may be ahead, but nothing is ever certain!


Just to put that into proof, here is some data for you to see the correlation:


Year: OPI

1976: -1.75

1977: -0.95

1978: -1.8

1979: -0.5

1980: -0.05

1981: -0.4

1982: -1.1

1983: -0.3

1984: -1.8

1985: -1.9

1986: -1.3

1987: -0.45

1988: 1.45

1989: 0.25

1990: 0.55

1991: 1.1

1992: 1.75

1993: -0.15

1994: 0.7

1995: -0.65

1996: -0.75

1997: -0.75

1998: 0.1

1999: -0.2

2000: -0.75

2001: 0.45

2002: -0.9

2003: -0.7

2004: 0.3

2005: -0.7

2006: 0.85

2007: 0.75

2008: 0.25

2009: -3.15

2010: -0.85

2011: 0.65

2012: -1.65

2013: 1.6

Take a look at some examples and research it, the winters that were cold/very cold had OPI’s of -1.5 or lower! For example, October 2009 had an OPI of -3.15 and that winter was exceptionally cold! Whereas October 2013 had an OPI of 1.6 and that winter was exceptionally mild! So, now, if I was to tell you that we were homing in on the second lowest OPI since the data started, what does that say? A cold winter may be ahead of us…


Next up is a minor part of the post, solar sunspots. Despite having quite a large sunspot recently the number is still low compared to other years and it looks to be on the decrease! Take a look at the graph below, you will see that the cycle has increased lower than the previous peak and will soon be on the decline by the looks! Could this play a key part in keeping things cold this winter? It isn’t extremely low but it may just be enough!


Finally, we have the Eurasian Snow Cover Extent during October. This one is a cracker this year! I will show you a picture of what snow cover was like on the 1st Oct 2014, this year:


Then finally, take a look at this cracker! The snowfall extent is hugely different to the beginning of the month!

October 27th:



Also, it’s larger than last year by a long shot! It’s said that there is a good correlation between big Eurasian snow cover extent and a cold winter for Western Europe, this is mainly due to the fact that firstly it causes surface cooling. This therefore strengthens the Siberian high in time, which increases the poleward heat exchange which can in turn cause an SSW. The SSW breaks down the stratospheric vortex and then we get a –AO which results in a cold winter. Also, take a look at the dramatic rise in snow cover this year, it truly is incredible, the largest extent since 1976! And this has a correlation to a cold winter!

Also, we can actually see that this strengthening snow cover may be affecting the stratosphere already. Look at the warming on the graphs, located above where we would find this extent of snow and ice. Could this be the first early weakening? The path to a cold winter?

Screen Shot 2014-10-28 at 16.26.51Screen Shot 2014-10-28 at 16.05.28



Lots of key signs and statistics are coming together as we approach the winter period, however this still needs monitoring! Dare I say that it is looking good? Soon we shall see, but my inkling at this stage for this winter is a –AO/-NAO and colder than average!


Thank you so much for reading, feedback and questions welcome!


Ollie Millin














41 thoughts on “LONG RANGE-WINTER 2014/2015

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  2. Hi from Finland! Very informative read. I think that the UKMO model may be too cold. Three months of easterlies is too much even if averaged. But if that really happens it could lead to really unusual phenomenon. I mean that the Baltic See could freeze over. Last time that happened was 1946-47 if I´m correct.

    We will see that. Mean temperature usually drops below zero ( winter begins ) in northern Finland by 22nd October. It is 16 days away. Hmm, and soon it is Christmas again :D

    • Thank you Marko! Yes interesting that the UKMO model says that, the signs are all very promising, I’ve also noticed that the Siberian snow is really picking up. It has a correlation with cold winters for us. Hope winter is good for you, do you have twitter?

  3. love your theory about the berries Ollie,it may interest you to know I picked 9 lbs of Blackberries here in South west Ireland(kerry) a few weeks ago,never had that much before,our winters apart from the bad ones of a couple of years ago are usually wet and muggy,it will be interesting to see how it works out this year!

  4. I´m bit old-fashioned guy, so I don´t have twitter. I´m pretty sure that there will be a lot of snow all around Europe next winter. You just have to be patient.

  5. hope you are right! I see the present cold spell has already gone totally against what many forecast for this month….just the second week of their forecasts! GIF charts show strong high builds over Scandinavia towards end of month bringing strong east / south east winds.

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  10. Great forecasts here Ollie, have been a keen follower of your long range outlooks for a year now. I find them quite impressive, keep it up, if you’re doing an Autumn/Winter blog let me know :).

  11. Doing a cruise from venice to barcelona in mid september to early October 2014 disembarking at Barcelona. cities visiting are Lake como, milan, venice, ravenna, dubrovnik, athens, kusadasi, mykonos, naples, rome, florence, toulon, barcelona and dubai.
    Your information on weather for places wiulc bd grestlg sporeviatef.

  12. Hi Ollie as you know many computer forecasts for the UK last Winter were totally wrong. The north eastern Seeboard of the U.S.A got our predicted Weather . I think this winter will be Wet & windy but Mild ! I hope I’m wrong ! But that’s the way I see it for South East England as of 5th September 2014.

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