UK Winter 2015/16 Weather Forecast Overview
When looking at the winter period, there are a variety of variables that can be looked at including seasonal forecast models, but also some global ‘indicators’ that may give some signs as to how the broader weather patterns may evolve through the winter period. Now we are approaching the end of November and with the three main winter months (Dec, Jan and Feb) just around the corner, there is increasing confidence regarding a broader pattern of weather across the UK through the coming winter.
UK Winter 2015/16 Weather Forecast
One of the primary global features that continues to dominate the news is the very strong El Nino within the tropical eastern Pacific that has developed over the last few months. This event is indeed one of the strongest El Nino’s in many years and is likely to have some impact on the weather across the UK and NW Europe in general through the winter period. There is a connection that El Nino’s can lead to the UK experiencing a colder than average winter, but other factors need to be taken into account as well.
There is a link and connection between the early winter and late winter being dominated by quite a split in the weather and this is due to the developing El Nino and other factors and variables and how they all inter-connect. This signal was picked up on in our initial winter forecast thoughts from a few months ago. That trend has continued and there is a link between El Nino and the early winter being dominated by mild, wet and windy weather and that of quite an abrupt change in the weather during the second half of the winter due to the connection between El Nino and the stratosphere (Sudden Stratospheric Warming), so through January and February and potentially into March as well. As was exampled back in March 2013 under the right weather patterns and conditions some severe winter weather can still dominate beyond the final month of winter and last well into early Spring.
Another interesting variable is the continued negative sea temperature anomalies to the west of the UK, within the North Atlantic. At the moment there is some confidence to suggest that this region of cold temperature anomalies within the North Atlantic will continue through the coming winter and importantly what this may do is make any westerly or north-westerly winds somewhat colder across the UK than normal. The reason for this is that usually cold arctic air that gets filtered out of Eastern Canada or Greenland, is often modified and ‘made warmer’ by the relatively warm North Atlantic sea temperatures by the time it reaches the UK. Clearly if the North Atlantic sea temperatures are colder than average and set to remain so through the coming winter, then, in theory, any west or north-westerly winds may well be colder than would normally be expected from a source over the North Atlantic. This may well aid in lowering the overall average temperature for the winter period and more particularly once we get into January and February.
Here at UKWF HQ we continue to prefer the outcome of a possible winter of two halves. The broader weather patterns as we move into December are likely to remain quite changeable and often dominated by low pressure over December. This doesn’t preclude the possibility of some short-lived colder and more settled spells, but generally an unsettled December is expected with temperatures near or slightly above average and rainfall most likely slightly above average too, especially across northern and western areas. As we progress further into the winter then a change to potentially colder weather is possible, but this is likely to be highly dependent on conditions and developments within the stratosphere, something which we will discuss below.
Latest Stratospheric Developments:
During the winter months the stratosphere (the region of atmosphere above the troposphere, where all our weather takes places) cools and as it does so low pressure develops over the polar region. There is a clear scientific connection between the intensity of the stratospheric vortex and that of the weather across the North Atlantic during the winter period. The colder the stratosphere then typically there is a heightened risk of zonal conditions developing across the North Atlantic leading to wet, windy and mild conditions for the UK. However, if the stratosphere warms, then for various reasons, this can allow more of a blocked pattern to develop which lowers the risk of wet, windy and mild weather, but increases the chances of colder weather and these patterns are explained below.
Now at the moment the stratosphere has cooled quite dramatically in the last few weeks and is forecast to remain a highly organised system as we move into December and the first opening month of winter. As a result of this there is relatively high confidence to suggest that the start of winter, at least, is looking like it will be a rather ‘typical’ mild, wet and windy one for the UK. Clearly there could well be some temporary spells of colder weather at times, but in terms of anything substantial or prolonged then at the moment we believe that December, at least, will be lacking any substantial or major cold weather outbreaks. As the winter progresses, and reverting back to earlier comments, there is then the possibility that the stratospheric vortex may well weaken and ‘become warmer’. If this process were to occur then there would be a heightened risk of colder weather during the middle and latter half of the winter and perhaps even into early spring and this is what we still believe is likely to happen this year.
So, in summary a mild, wet and windy start to winter is looking increasingly likely with December potentially mild and stormy at times and with just short-lived cold snaps. However, as we progress into January and February then markedly colder weather may well develop. Temperatures throughout the winter period overall are likely to average out near to normal as a milder than average December could then be balanced out with colder conditions in January and February, so near average temperatures are the ‘most likely’ outcome overall. Rainfall totals are more difficult to judge, but generally are likely to be near or slightly above average, so perhaps a wetter than average winter is more likely, especially so across more northern and western areas of the UK.
A full review of the winter 2015/2016 forecast will be issued during March 2016. As ever stay with us here at UKWF throughout the winter season for all the latest on the weather across the UK.
Chief Forecaster: Matt