In this post I shall take a look at the El Nino, it’s role and importance of strength and position over the equatorial Pacific. The role of sea surface temperatures over the North Atlantic and the overall Pacific and Atlantic’s influence on the atmosphere, the behavior of the current winter season down in the southern hemisphere and whether it can be looked at as an indicator to the upcoming n hemisphere winter. Also, the current state of the solar cycle and whether the recent volcanic activity has baring on our atmosphere a couple of years on….

Role Of The El Nino

It’s very important to not think WARM when it comes to El Nino, the nino’s strength and position can make all the difference between a warm and cold winter for both the United States and Europe.

As you can clearly see, the warmth of the nino is shown on this JAMSTEC forecast model below, it’s tongue of warmer than normal SST’s are spread quite evenly from the Peruvian coast out into the central Pacific during the Sept-Nov period but when you look at the where the warmest waters are for the Dec-Feb period, the model has those warmest waters in the central Pacific. This is crucial to the United States because the position of this warm water can determine where that ridge sets up.

Have those warmest waters just off South America and you’ve got a trough over the northeast Pacific extending into western North America and a big ridge of warmth over the heart of the Lower 48.

Notice the cold over the central Pacific, this should have the ridge back west and although perhaps reaching into western North America, it would support a Great Lakes to East Coast trough and an open door to cold air flowing frequently down from the north.

Weak El Ninos can bring not only cold but snowy winters to the Eastern US with a storm track riding up the East Coast, this would support an active Nor’easter season and with a trough streaming cold air down from Canada and moisture flowing in off the Atlantic and Gulf with warmer than normal SST’s off the US, this would fuel heavy snows. Remember back to the epic snow year centred over the Mid-Atlantic in 2009-10?

Current summer pattern has similaritites to 2009

During summer 2009 we saw a very wet summer here in the UK and a hot, dry summer over the heart of the United States with focus over the Plains like we’re seeing now. During that summer, we saw a tanking of the NAO into deep negative just like we’re currently seeing and with the El Nino state very similar, one would look at this and take this as an interesting analog year to compare to.

If we use 2009 as an analog with similar nino and NAO behaviour then one would expect a cold October for the UK, remember it snowed in London back in October 09 while it was brutally cold in the Western US? November on the other hand was record wet and warm, recall the Cumbrian floods and all-time record UK 24-hour rainfall record? I do believe the warmest, most settled part of our summer is still ahead of us with a possible warm late August through early Sepotember period with a positive NAO but a flip into negative with cold October looks possible. A warm end to autumn is likely and a cold autumn is on offer for the US as the Jamstec suggests below. Just look at both the surface air temp anomalies and precip forecast off the model for the Sept through Nov period, very interesting.

NAO could follow in 2009’s footsteps, Strongly negative, when it counts!

Of course last winter was a dissapointment with the Azores ridge persistently holding on over the UK. I blame the drought from the previous summer for this. Remember back to the later part of January and much of February. While there was blocking.. rather than it being over Greenland, it was over the UK. This position kept North America warm (very cold in Alaska, N Canada) but brutally cold over the heart of Europe.

Pay close attention to the chart 2nd from top.. notice the forecast temp profile of the North Atlantic, this tripole of warm over cold over warm indicates a favouring for high latitude blocking. The warm SST’s further north shows the model seeing the correct SST environment for blocking to develop and the warming of the waters due to high pressure. Your classic Greenland block! while the cold water shown over the North Atlantic is ‘south’ of Greenland, this indicates where the cold will be. Note the cold water extending from eastern North America to the North Sea. The model sees cold and of course you only have to look at the forecast air temp anomalies to see that this model has it colder than normal over the UK and a good chunk of the US. Notice the warmth over Alaska. When it’s cold in Alaska, it’s warm in the Lower 48 and if warm in Alaska, it’s cold down below! Notice also how Europe is warm, the model is seeing the trough in the west of the continent while warm with downwind ridging in the east. It’s very similar to 2009 that’s for sure.

Can we be sure, we’re going to see blocking this winter when it really counts? If you consider the recent trend towards enhanced blocking over the northern latitudes, remember warmer waters, further north tends to support stronger heights aloft (higher pressure), so combine this with recent volcanic activity in Iceland, keep in mind that influence from volcanoes can have effects on the atmosphere for years not just months following an eruption(s).

When comparing the trend this summer to 2009 which saw the big dip into negative with the NAO during the heart of the 2009 summer and wet pattern for UK as well as the recent trend, combined with the liklihood of a weak nino, centred over the central Pacific (very like 2009), I believe the UK and Ireland could well see a very different winter to 2011-12 and somewhere more similar to 2009-10. El Ninos following back to back La Ninas with a cold Pacific signal and warm Atlantic signal tends to support cold winters for the United States and Western Europe. Keep in mind folks that the 2009-10 winter OVERALL was worse than 2010-11 despite a more brutal period of cold. It’s very easy to look at last year and perhaps think warm when it comes to nino and determine from that, that winter this year will follow in last years footsteps but it simply doesn’t work that way. There is different variables on the table, even the solar cycle is different as it’s past it’s maximum in cycle 24 and activity is quietening down again. Though we appear to be entering a colder period on earth overall, winters like last year will still occur but the previous two I believe is a sign of a trend.

Remember these are INITIAL IDEAS and not my OFFICIAL forecast. I am wanting to show you where my thoughts on this winter are heading towards and what players are involved and what their role is likely to be. I shall be releasing my official winter forecast for both Europe and the United States on ther 31 October.

Tags: el nino winter, uk winter forecast 2012-13, us winter forecast for 2012-13, winter forecast 2012-13