CHORLEYWEATHER.COM: UK Winter Forecast 2016/17: La Nina Now Unlikely!!!!

Written by on September 21, 2016 in Rest of Europe, Summer 2016, United Kingdom & Ireland with 0 Comments

Here’s some interesting thoughts on the 2016-17 winter from Stuart Markham of Chorley Weather. Always good to share and learn from others!

Be sure to follow Stuart on twitter @_weatherstu

Source http://www.chorleyweather.com/uk-winter-forecast-201617-la-nina-now-unlikely/

La Nina the sister of the perhaps more well known phenomenon El Nino, looked likely to develop this Autumn given all the model guidance but a weak Nina was always suggested rather than anything much stronger. However recent analysis has suggested that the ENSO region will remain neutral through the winter period with neither El Nino or La Nina expected to develop. This will have impacts as both can be major drivers in weather patterns, so any previous winter forecasts that included La Nina as a driver will now have to re-evaluate their forecasts.

La Nina always looked borderline to develop with such an ensemble spread showing with the model guidance and taking enso forecasts earlier in the year isnt very trustworthy anyway, as the models do struggle to get to grips with the situation at such length.

capture

What does this mean for the UK Winter Forecast? Well as ever nothing is certain but looking back though previous years (from 1950 – 2015) that have had a moderate plus strength El Nino to start the year and then had ENSO neutral through the winter, we come up with four years 1966, 1983, 1992, 2003. Yes we thought there would be more years as well and we are going to reduce these years to three because global weather patterns in 1992 were still heavily influenced by the effects of  Mount Pinatubo thus the data is somewhat unreliable to use in a historical sense.

So taking the years 66, 83 and 03 combined we have generated an analogue for December which throws quite a interesting pattern. Higher heights are often portrayed to be to the west of the UK with a deep trough to the north generating an NW flow more often than not. This wont be an extremely cold flow but certainly cold shots will be felt with transient low’s but equally we may also get numerous warm sectors as well from these lows. So a mixed December looks likely continuing the changeable weather theme we’ve already seen this summer and autumn.

december-neutral

January however paints a very different picture with northern blocking very pronounced with a strong signal for below average heights across much of Europe. This flow will bring cold air across the UK on a E/NE flow quite often and with it some wintry weather, particularly across eastern areas of the UK. Quite a cold signal here for sure.
january-nuetral

February shows another change in pattern with higher than normal heights across the UK, bringing generally dry weather. What temperature the air will be with this flow is difficult to assess. The flow could well come from the east, which would be a cold direction for the time of year but this largely depends on what air mass is across the continent at the time.

february-neutral

So in summary given the ENSO situation coupled with our historical data a mixed winter looks likely with a range of weather possible. That may seem like a bit of a ‘easy way out’ in forecasting terms but given the current guidance there isn’t a lot to go on. Our data at least points to January as being the most likely month for cold weather but it is entirely possible late December may prove cold as well. Equally December could prove a milder and more unsettled month with Febuary perhaps turning out drier with a mixture of warm and cold temperatures. As ever there are many days and weeks before winter starts and we’ll be updating on the run in once more data becomes available or indeed more clear.

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