Mild wet winter continues in early January figures

16 01 2014

Provisional half-month statistics up to the 15th of January show a continuation of the generally mild and wet theme of the UK’s winter thus far.

The mean UK temperature up to the 15th of January is 5.1 °C, which is 1.5 °C above the long-term (1981-2010) average.

The mild January so far follows on from a mild UK December, which had a mean temperature of 5.7 °C, which is 1.8 °C above the long-term average – making it the eighth mildest December in records dating back to 1910, and the mildest since 1988.

It’s a similar story with UK rainfall. We’d normally expect about 48% of the January average rainfall by the 15th of the month, but the UK has seen 87.9mm so far – which equates to 72% of the January average.

As usual, there are regional varations. England has been particularly wet so far this month, having already seen close to its full-month average, and Wales is not too far behind. Scotland and Northern Ireland, however, are closer to the ‘normal’ amount of rain we’d expect at this stage.

The wet January so far once again follows the theme set in December, which saw 184.7mm of rain – which is 154% of the average for the month.

While this means January, and winter, so far have been mild and wet, it doesn’t mean they will finish that way. We often see half-month or half-season figures which then change dramatically by the end of the period. So the message is, it’s too early to judge how January 2014 or winter 2013/4 will finish up.

The main reason for the mild and wet weather so far is that we have seen a predominance of west and south-west winds, bringing in mild air from the Atlantic – as well as generally unsettled conditions.

The table below shows provisional figures from 1-15 of January, with actual figures so far compared to full-month averages. We would normally expect rainfall and sunshine to be about 48% of the full-month average at this stage.

Mean Temperature Sunshine hours Rainfall  
January 1-15
Actual Diff from Avg Actual % of Avg Actual % of Avg
  degC degC hours % mm %
UK 5.1 1.5 26.1 55 87.9 72
England 6.0 1.9 34.7 64 80.4 97
Wales 5.8 1.7 20.6 42 137.7 88
Scotland 3.6 1.0 15.4 43 91.2 51
N Ireland 4.4 0.2 14.6 33 62.8 54




October set for top ten warmest

1 11 2013

5 November 2013 Update – The full month figures are available in our latest blog

Early statistics for October up to the 28th of the month suggest this October is likely to be one of the warmest in records dating back to 1910.

Map showing relative warmth of October temperatures across the UK.

Map showing relative warmth of October temperatures across the UK.

The mean temperature for the UK from the 1st to the 28th is 11.6 °C, which is 2.1 °C above the long-term (1981-2010) average. It’s currently ranked joint fifth warmest in the records, but this could change once the final three days of data have been included.

Mild temperatures were experienced across all parts of the UK – with October currently being in the top ten warmest for England, Wales, Scotland and Northern Ireland. However, it was particularly mild in Wales, with this October currently ranked as the joint warmest on record alongside 2001.

There were no autumn heat waves through October, just a persistence of mild conditions – particularly mild nights – and frost has been rare through the month.

October 2013 is also notable because it was dull and, for most places, relatively wet. Sunshine hours are currently below the long-term average, while rainfall is already above ‘normal’ levels for everywhere apart from Scotland – which is about average.

Below are figures from 1-28 October, and we’ll update on the full-month figures early next week.

Below is a table showing statistics for 1-28 October, and we’ll update with full-month statistics early next week.

Mean temp Sunshine Rainfall
October 1-28 Actual (°C) Diff to Avg Actual (hrs) % of Avg Actual (mm) % of Avg
UK 11.6 2.1 67.3 73 147.6 116
England 12.6 2.2 74.4 72 131.6 143
Wales 12.3 2.4 66.7 72 208.9 123
Scotland 9.7 1.8 52.7 70 157.9 90
N Ireland 11.2 1.8 84.1 96 145.6 122




UK’s unsettled weather and the jet stream

21 10 2013

The UK is set to see unsettled weather throughout this week as heavy rain and windy conditions are expected to affect many areas, whilst temperatures will remain mild for the time of year.

We talk about the jet stream quite a bit in the UK because it has such a big influence on our weather, and this week is no exception as it’s playing a leading role in determining the unsettled outlook.

What is the jet stream?

The jet stream is a band of fast moving westerly winds high up in the atmosphere which circle around the pole in the northern hemisphere. It can feature winds of up to 200 knots (230 mph) or more, and these winds tend to guide wet and windy weather systems which come in off the Atlantic.

The jet moves around a fair bit and its position can have a big impact on weather here in the UK depending on where it is.

If the Jet is over the UK or just to the south, we tend to get a lot of wet and windy conditions as it brings weather systems straight to us. If the jet is to the north of us, it guides that changeable weather away to the north to leave the UK with more settled conditions.

What’s the jet stream doing now?

Unsurprisingly given the outlook for this week, the jet is positioned more or less directly over the UK – but it’s the detail of its track which is important.

As you can see from the picture below, the jet currently swoops south from western Canada – moving over the Atlantic before taking a sharp turn north to head over the UK.

Forecast chart showing  expected position of the jet stream at 1pm on Tuesday 22 October

Forecast chart showing expected position of the jet stream at 1pm on Tuesday 22 October

This means relatively cool air is being dragged south then over the Atlantic, where warmer seas heat the air from below. This causes the air to warm and rise – creating instability and generating cloud and rain.

By the time weather systems reach they UK they have picked up a lot of rain and relatively warm air, bringing us the wet but mild conditions we are currently seeing.

What’s the weather outlook?

Currently unsettled weather looks set to impact the UK through the week, with heavy rain affecting many areas at times.

There may be more settled conditions on Thursday, and perhaps again on Saturday, but looking further ahead into the start of next week the outlook is for unsettled weather to continue.

You can stay up to date with what to expect with our detailed forecasts out to 5-days and our weather warnings, as well as a general view of what we expect out to 30 days.

You can find out more about the jet stream in our YouTube video.





Guest blog – How the Atlantic may influence wet summers

19 06 2013

This morning there has been a lot of media coverage following a workshop held here at the Met Office HQ in Exeter on a recent run of unusual seasons in the UK.

Much of this centred around recent research by the University of Reading, presented at the workshop yesterday, which suggested Atlantic ocean cycles – specifically one known as the Atlantic Multidecadal Oscillation (AMO) – can have an influence on UK summer weather.

Here Professor Rowan Sutton, from the University of Reading, explains that research in a bit more detail:

 

“Last year, Buwen Dong and I at the National Centre for Atmospheric Science published a paper in Nature Geoscience about the link between slow changes in the temperature of the North Atlantic Ocean and weather patterns.

In particular, we presented evidence of a link between warm surface temperatures in the North Atlantic and a higher frequency of wet summers in the UK and Northern Europe.

This research built on earlier research I published with another colleague, Dan Hodson, in Science in 2005 and an important study by Jeff Knight and colleagues at the Met Office, which was published in 2006.

In our 2012 paper we showed that a rapid warming of the North Atlantic Ocean which occurred in the 1990s coincided with a shift to wetter summers in the UK and northern Europe and hotter, drier summers around the Mediterranean. The pattern identified matched that of summer 2012, when the UK had the wettest summer in 100 years.

Observational records show that the surface temperature of the North Atlantic has swung slowly between warmer and cooler conditions, and the present warm phase has a similar pattern to warm conditions that persisted throughout the 1930s, 40s and 50s. During the 1960s, 70s and 80s cooler conditions prevailed.

Computer simulations suggest that these changes in ocean temperature affect the atmosphere above. Warmth in the North Atlantic causes a trough of low pressure over western Europe in summer and steers rain-bearing weather systems into the UK.

An important question of interest to many people is how long will the current pattern of wet summers in northern Europe persist? This is a key research question and we don’t yet have precise answers.

In our 2012 paper we stated: “Our results suggest that the recent pattern of anomalies in European climate will persist as long as the North Atlantic Ocean remains anomalously warm.”

How long might this be?  There is strong evidence linking the swings in the Atlantic Ocean surface temperature to the “overturning” or “thermohaline” circulation of the Atlantic.

This circulation appears to have intensified in the 1990s. Following such a strengthening, a subsequent weakening is expected, as various feedbacks exert their influence.

For example, the surface warm waters transported northward by the overturning circulation have relatively low density which inhibits their tendency to sink, and acts to slow the circulation. Such a slowing cools the North Atlantic.

The time scales involved are in the range between a few years and a decade or two.  Progress in Decadal Forecasting, such as the pioneering work at the Met Office, and critical observations such as from the NERC-funded “RAPID” array, should help us to reduce this large range of uncertainty, but it is a challenging problem and advances may take some years.”





Recent rainfall totals

24 12 2012

Rain has continued to cause disruption across parts of the UK, with overnight rain adding to significant totals over the past few days.

The wettest place in the UK (and Scotland) since the heavy rainfall began on 19th December to 6am this morning has been Tyndrum in Perthshire, with 155.0 mm of rain.

Cardinham near Bodmin, Cornwall, is the wettest place in England with 128.8 mm of rain and the wettest place in Wales has been Mumbles Head, West Glamorgan, with 107.0 mm of rain.

Ballypatrick Forest in Antrim has been the wettest place in Northern Ireland, with 89.0 mm of rain.

Some areas have exceeded their full-month December average since the 19th – such as Plymouth, Devon, which has seen 128.8mm of rain compared to a December average of 118.8 mm.

Below is a table of the wettest places in the UK from 0000 HRS on 19th December to 0600 HRS today, 24th December. The final column shows the monthly average for December, clearly showing some places have exceeded their monthly totals:

SITE NAME AREA PRECIP AMOUNT(mm) DEC AVG(mm)
TYNDRUM PERTHSHIRE 155.0 300.9
CARDINHAM CORNWALL 128.8 155.1
PLYMOUTH DEVON 127.4 118.8
LISCOMBE SOMERSET 125.2 171.2
OKEHAMPTON DEVON 115.0 184.2
MUMBLES HEAD WEST GLAMORGAN 107.0 110.3
TREDEGAR GWENT 102.2 169.0
CARDIFF, BUTE PARK SOUTH GLAMORGAN 97.0 125.3
SENNYBRIDGE NO 2 POWYS 96.2 179.5
ST ATHAN SOUTH GLAMORGAN 93.2 122.4
DYCE ABERDEENSHIRE 92.4 76.1
CARTERHOUSE ROXBURGHSHIRE 92.4 132.0
CRAIBSTONE ABERDEENSHIRE 92.0 79.8
BALLYPATRICK FOREST ANTRIM 89.0 133.9

There is more unsettled weather to come this week, so for the latest information keep up to date with our forecasts and warnings.





Is it the wettest UK summer on record?

26 08 2012

This summer started with the wettest June in the UK in the national records which go back to 1910 and was followed up by a wetter than average July (16th wettest), so are we set for the wettest summer on record?

Officially, in meteorological terms, summer runs from the start of June to the end of August – so there are still a few days to go for this year.

The Met Office holds many different climate datasets but uses the UK national series that goes back to 1910 when referring to records.

In this dataset, the record to beat was set in 1912, when the UK had 384.4mm of rain – although we don’t have to look too far back to find a very wet summer, as 2007 is third in the rankings with 357.8mm. The 1971-2000 average for the UK in summer is 226.9mm.

Looking at this year, we have the figures for June and July, but for the UK as a whole we currently only have data up to 15 August – which show rainfall had been slightly below average to that point.

That means we can say with some certainty that we have seen 300.8mm of rain so far this summer (145.3mm in June, 115.9mm in July, and 39.6mm to 15 August), ranking 20th in the records.

There has been a fair amount of rain since then, so that ranking is sure to have climbed – but it’s not possible to say until all the numbers have been crunched at the end of this month.

It’s important to remember that the UK total rainfall is effectively an average of the rain that falls across the whole of England, Wales, Scotland and Northern Ireland – so looking at one station, or even one country, isn’t a reliable indicator of how much rain we’ve seen for the UK as a whole.

We can say that this summer is likely to be one of the wettest on record – some may argue that, as it’s already in the top 20% in records dating back to 1910, it already is one of the wettest on record.

We can also say that this year has continued a disappointing run of UK summers which started in 2007 – all of which have seen above average rainfall and, with the exception of 2009, below average sunshine hours.

However, we cannot say where this year will finish in the rankings or whether it will challenge the record set in 1912. For that final assessment, we’ll have to wait until after the end of August.

You can see a discussion about the causes of this year’s unsettled summer in an article posted earlier on our blog.





Improving picture as many start school holidays

18 07 2012

After weeks of heavy rain across parts of the UK, conditions are set to improve for many areas this weekend.

More heavy showers will affect some parts during the rest of the week, but by Saturday most areas will see drier weather with any showers few and far between. Temperatures will reach the low 20s Celsius.

Sunday will see the improved weather continue for a large part of England and Wales, with mostly dry weather and bright or sunny spells expected. However, the north and west of the UK, can expect some rain – which will be heavy in places – with strong winds.

Drier weather for many, with rain where it’s needed

Martin Young, Chief Forecaster at the Met Office, said: “As we move towards the weekend we will see a return to a more normal summer weather pattern for the UK. This will bring dry and bright conditions to southern parts over the weekend, and some much needed rainfall to the far north west of Scotland – where it has been exceptionally dry.”

Jet stream returning to ‘normal’ position

There has been a lot of talk about the position of the jet stream in relation to the recent wet weather, with this narrow band of fast flowing winds having been much further south than we would expect at this time of year.

Over the next few days, the jet stream is expected to move to its more usual position to the north of the UK, guiding rain-bearing low pressure systems from the Atlantic away from the country. This is why we expect to see a move to more normal summer conditions, with the south and east seeing the best of any drier and brighter conditions.

The above picture shows the position of the jet stream on 18 July 2012.

The forecast for 23 July 2012 shows the jet stream much further to the north.

Looking to the Olympics

There is understandably a huge amount of interest in what the weather will be doing at the end of next week in time for the Opening Ceremony of the Olympic Games. However, it’s still a little early to give a detailed forecast for the Olympic Stadium for the big opening event.

Sandie Dawe, Chief Executive at VisitBritain said: “The weather is a peculiarly British obsession, our international visitors come all year round for our temperate climate and enjoy a dash of unpredictability. Sunshine will help to get us all in the party mood, as we show the warmth of our welcome and the British know how to host not just a great Games but a great party too. Come rain or shine – Britain is the place to be in 2012.”

As ever, we’ll be working round the clock to make sure everyone – from the UK public, to athletes, coaches, and the organisers of the Games – has the very latest picture of what the weather has in store. For the latest information, keep up to date with our online forecasts and warnings.





How is the weather affecting pollen?

17 07 2012

The weather has been very unsettled during June and the start of July, and this has been reflected in the pollen counts. As we predicted back in May, there have been some very high counts, but there have also been some days when the pollen has been washed out by the heavy rain.

The heavy rain we have seen has maintained the strong growth of native plants that started with the very wet April.  This means that there is an ample supply of pollen from grasses and weeds such as nettle. However, the unsettled weather has meant that pollen counts have fluctuated significantly from day to day and place to place.

Further high pollen counts are expected during any drier and sunnier interludes. This will increasingly come from weed pollens.

The graph below shows how the pollen count has changed significantly from day to day this summer, in response to the weather, and that on high days it has been much higher than last summer:

Pollen count has changed significantly from day to day this summer in response to the weather.

Patrick Sachon, Health Manager at the Met Office said: “The unsettled weather this summer has led to a fluctuating pollen count but as expected we have seen some very high levels when the weather has been good. Further high counts are expected during any settled, drier weather. We would therefore recommend that hay fever sufferers check the pollen forecast sponsored by Benadryl, every day and do all that they can to manage their symptoms.”





Is this the wettest June on record?

26 06 2012

Update: Provisional Met Office figures for the whole of June are now available at: Met Office confirms wettest June in over a century

We all know that, so far, it has been a very wet June in many parts of the UK – but just how wet has it been?

Met Office figures show that, up to the 24th of the month, the UK had seen 122.3 mm of rain –ranking as the third wettest June since records began in 1910 and well over one-and-a-half times the UK average.

So this month is currently just behind the second wettest June in 1912, which saw 124.5 mm of rain, and a little way off the wettest June in 2007, which saw 136.2 mm.

Clearly there are several more days to go and there is some rainfall in the forecast, so not possible to categorically say exactly where the month will finish in the overall records – however it is safe to say it has been a disappointingly wet month.

It’s important to note the rainfall this month hasn’t been evenly spread over the UK. Some areas have seen a great deal of rain, with 52 observation sites breaking record rainfall totals.

Not all of these records are significant as some of stations only have a very short history – for example, Usk in Monmouthshire has only been taking measurements for one year. However, at the other extreme, Otterbourne in Hampshire has been operating for 119 years.

While some areas have already seen record rainfall, others are lingering close to their all-time June minimum. Six stations are currently still below their lowest June rainfall total – but this could change by the end of the month.

What is interesting as that most of the drier stations are in the far north and west of the UK – areas which we would normally expect to see the most rainfall.

UK rainfall map

Map showing rainfall up to the 24 June 2012 compared to the1971-2000 average. Many parts of the country have seen double their normal amount, while the far north west has seen much less than usual.

 

This illustrates the story behind this month’s weather, as the rain-bearing low pressure systems moving in from the Atlantic which normally track to the north of the UK have been taking a much more southerly route, soaking parts of the south while the far north west has remained unusually dry.

One of the main reasons for this is the position of the jet stream. This is a narrow band of fast flowing westerly winds (ie blowing from west to east) high in the atmosphere.

This band moves around and changes its track, and where it sits can impact the UK’s weather. When it flows to the north of the country it can guide low pressure systems away from the UK (but they often clip the far north west of the country as they pass by).

Throughout this June the jet stream has had a much more southerly track, allowing those low pressure systems – with their wind and rain – to come straight over the UK to bring heavy rain to more southern areas while the north west remains relatively unscathed.

You can find out more about the jet stream in our YouTube video.





Why does it always rain on the UK?

9 05 2012

After the wettest April in records dating back to 1910 and an unsettled start to May, parts of the UK are set to see more heavy rain today and tomorrow.

With all the wet weather, many people have been asking what is to blame and whether something unusual is going on.

In an earlier article on this blog we looked at how the jet stream has influenced the recent spell of unsettled weather, but stressed it is not the only factor at play.

While the jet stream may be an influence, there is nothing unusual about its current position and it regularly behaves in this way.

With that in mind, it’s possible to go a step further and say there is nothing unusual about the UK’s weather over the last few weeks.

That may sound odd on the back of a record-breaking wet month, but we do expect to see records broken and they do topple fairly regularly for one area or another.

The past April fits into this expectation – it was exceptionally wet, but only slightly wetter than the previous record set just a few years ago in 2000 and there are several years close behind.

We only have to look back another month to see that March was the joint warmest on record for Scotland. Looking further back, parts of the UK have seen some of their driest months on record in the last year or so, and we saw the coldest UK December on record in 2010.

The mixture of record-breaking months in recent history illustrates what’s called natural variability – which is a way of summing up the inherent random or chaotic nature of weather. This is why our weather is different from one week, month or year to the next.

Here in the UK that variability is particularly noticeable because of our location. We sit in the mid-latitudes where cold air from the poles meets warm air from the tropics, and have the Atlantic on one side and the large landmass of continental Europe on the other.

All these factors mean our weather can be highly variable and we can see periods of unsettled, wet and windy weather at any time of year – a challenge that the Met Office has to rise to every day to provide the accurate weather forecasts that you, businesses and our government partners have come to expect.








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