Are you dusting off your fur coat, woolly hat and scarf while reaching for another log to throw on the fire? That would certainly be a natural reaction after reading recent newspaper coverage of winter weather warnings.
Various headlines have shouted about “coldest winter for 50 years with months of snow” and “36 days of snow”. The portents for this severe weather come from diverse sources - for instance from the warm oceans off Peru to cold seas in the Mid Atlantic and even the very early arrival of a migrating swan to a bird sanctuary in Gloucestershire.
These wild winter forecasts have not come from the UK’s official government-funded weather service, the Met Office.
That organisation's latest seasonal outlook, covering the period from November to January, is in sharp contrast. It suggests a greater probability of mild, wet and stormy conditions, at least for the first part of the winter.
The Met Office doesn’t rule out colder interludes in our weather and also suggests the outlook for late winter into February may be different with colder conditions possibly on the cards.
In a blog on the Met Office website Jeff Knight from the Met Office Monthly to Decadal Prediction team has been looking at the global climatic factors which can influence the British winter.
There are a number of factors which can influence the British winter to a greater or lesser extent:
- El Nino
- Atlantic water temperatures
- Winds high up in the atmosphere over the equator
- Easterly winds
There have been plenty of media reports about the strength of this year’s El Nino event - a weather phenomenon relating to the warming of ocean temperatures in the equatorial Pacific which happens every few years.
It could be that this year’s event develops into the strongest on record. While the effects of this are linked to weather events across the globe, the Met Office says its impact on Europe is relatively subtle.
Currently the sea surface temperature in the Mid Atlantic is considerably lower than normal and this has led to some of the chillier winter weather predictions that have hit the newspaper front pages.
The Met Office says this is unlikely to have a strong impact on temperatures over the British Isles. And with warmer seas further south in the Atlantic, on the contrary, it may even make it milder, wetter and stormier.
Britain’s chilly winters nearly always have an eastern component - the so-called “beast from the east” - when we get a cold air blast from Eastern Europe and Scandinavia.
Jeff Knight says: “Eastern Europe and Scandinavia are 10-20°C colder than the Atlantic Ocean in winter, so our weather will depend much more on how often winds blow in from the north and east than whether the Atlantic is 1-2°C cooler than usual.”
Coldest five winters in East Anglia
- The most recent cold winter in East Anglia was 2009/10 which was the eleventh coldest on record.
While trying to identify trends in UK winters the Met Office also looks to winds high up in the stratosphere above equatorial areas. This is home to the Quasi-Biennial Oscillation (QBO), a cycle that sees winds switch from easterly to westerly and back roughly every 27 months.
Currently this is in a westerly phase which would suggest a bigger chance of a milder and wetter winter.
Other high-level wind circulations over the Arctic can also give a clue to the prospects for a cold UK winter. A breakdown in the circulation of stratospheric winds around the North Pole can set-up an eastern weather pattern over Europe cooling things down, This last happened in late winter/early spring 2013 which produced the lowest March daytime temperatures on record in East Anglia. Met Office computer models do suggest an increased likelihood of this weather pattern being set up again from January onwards but Jeff Knight says this is “tentative” at this stage.
The Met Office seasonal outlook doesn’t rule out colder spells of winter weather from time to time. There is also an increased risk of colder weather developing from late January onwards although the Met Office says “it’s too early to be confident about this signal.”
As ever the Met Office outlook for the next three months is couched in terms of probability, likelihood and risk. So while there is a greater chance for a mild and wet winter season that doesn’t rule out a fierce and cold winter - it’s just less likely but not impossible.
In the meantime, we will be having another mild Halloween after the record-breaking warmth of Halloween 2014