FORECAST: EARLY WINTER 2018/19 – Will ‘The Beast’ Return?
It’s been an extraordinary year of weather and, unsurprisingly, in the wake of the ‘Beast from the East’ and the summer heatwave, there’s already much speculation about the winter ahead. As the days shorten, some will be relishing the prospect of colder weather and hoping for snow. Others already can’t wait for next spring to arrive! So, our view on whether the winter is ‘good’ or ‘bad’ will be subjective. As always, our forecast here is an objective one, based on all the available evidence. Detailed forecasts of specific weather events, times and locations are simply impossible at such range, despite what some may tell us.
THE KEY FACTORS
There are many factors that are known to influence the UK’s weather patterns in winter. However, the way these factors interact with one another is complex and still not fully understood by the world’s leading scientists. To make matters worse, there are, undoubtedly, some ‘unknowns’ in there too. Despite our great advances in shorter-range prediction, these conspire to make seasonal forecasting very challenging!
These are some known ‘players in the pack’ that will have a significant say in determining the behaviour of atmospheric waves of energy, and hence our weather, this winter:
- El Nino: Warming waters in the central and eastern tropical Pacific Ocean
- Atlantic Ocean Temperatures: Discrete zones of warm and cold waters
- Sun Spots: We are reaching a minimum in the 11-year cycle of sun-spot activity
- Stratospheric Winds: Oscillations in wind strength and direction at the top of the atmosphere
By looking back at previous years, we can discern hints of how such factors have conspired to affect UK winter weather in the past.
In addition, computer-generated seasonal forecasts are produced by a number of meteorological centres around the world. These apply physical equations to the current state of the atmosphere and oceans to predict the weather in the months ahead.
All these elements have been assessed in the shaping of this forecast.
A number of other centres have already issued their initial early winter forecasts for the UK. These suggest that a strong westerly jet stream is likely for much of the period, making a mild, wet and windy (even stormy) weather pattern quite dominant over occasional colder snaps.
However, based on all the latest available observations, historical analogues and computer forecasts, we suggest the following for December-January:
- A strong North Atlantic jet stream will often propel active wet and windy weather systems towards the UK. However, periodically, these will be slowed or deflected by a ‘blocking’ area of high pressure, centred across northern Europe, including Scandinavia.
- As this ‘blocking’ high pressure area feeds air of an arctic or continental source into the UK, there will be several periods of drier and chillier than normal weather.
- A number of snowfalls are likely, especially as Atlantic weather fronts approach the ‘blocking’ high pressure area and slow down. This is most likely across central, northern and eastern parts of the UK.
- As fronts introduce milder air from the Atlantic, wettest spells are likely across some southern and western areas of the UK.
- At times, mild air will spread widely across the UK from the west as the ‘blocking’ high pressure area is periodically displaced. It may well be that the UK repeatedly finds itself in the middle of this ‘battleground’ between mild and cold air.
- One or more stormy spells are quite possible, especially across southwestern areas.
The ‘Beast from the East’ that occurred late last winter was the result of a Sudden Stratospheric Warming. It is possible that an ‘SSW’ will occur in this period. However, should one occur, at this range it is not possible to predict the timing or strength. A repeat of last year’s extreme conditions is statistically unlikely.
In the light of further evidence we will, of course, update this forecast, as necessary. Additionally, John Hammond’s Month Ahead will continue to be updated every week.
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