The jet stream and why it’s too early to write-off summer

There have been one or two stories in the press today saying we’re in for another washout summer, which would rightly inspire collective misery across the country.

However, it’s a far too early to be writing off any chance of a decent summer season – after all, it doesn’t officially start (for us meteorologists) for more than two weeks (on 1 June).

It appears the news stories are borne out of the current position of the jet stream, a band of fast moving westerly winds high up in the atmosphere. But why is this important?

A quick Jet stream explainer

The jet stream tends to guide the generally wet and windy weather systems which come in off the Atlantic. So, if it’s over us or just to the south, we tend to get a lot of wet and windy weather – which is what we expect through winter.

If the jet is to the north of us, it guides that changeable weather to the north to give us more settled conditions – which is what we expect in the summer.

(You can read a bit more about the jet stream, how it impacted our weather last year, and any potential connections to climate change in a blog story we wrote last year).

What’s going on now?

Right now the jet stream is sitting to the south of the country and it is influencing the unsettled weather we are seeing at the moment.

Forecast chart showing position of the jet stream at midday on 13 May 2013

It’s fair to say that this is roughly the position it was in for extended periods during the exceptionally wet weather that we saw last year, particularly in June.

Crucially, however, the jet stream does move around quite a bit and it can change its track significantly in just a few days. So the current position of the jet stream does not mean that it’s stuck in that position.

Looking ahead

Much like our weather, it’s a huge challenge to predict the exact track of the jet stream more than five or six days ahead, so there’s still a great deal to play for in the outlook for our summer.

In short, it’s far too early to write-off summer 2013 based on the current position of the jet stream.

To get the best information on what to expect you can see the latest detailed forecasts out to 5-days on our website, 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.

Statistics for December and 2012 – is the UK getting wetter?

Provisional statistics from the Met Office show 2012 was the second wettest year in the UK national record dating back to 1910, and just a few millimetres short of the record set in 2000.

The exceptionally wet year was characterised by a dry start which quickly gave way to very wet weather, with April and June both being the wettest on record.

Unsettled weather continued through to the end of the year, with December being the 8th wettest on record for the UK.

Throughout the year, accurate forecasts and warnings from the Met Office have helped everyone across the UK plan and prepare for the worst impacts of the extremely wet weather we have seen.

The persistent wet weather resulted in total 2012 rainfall for the UK of 1330.7 mm, which is just 6.6 mm short of the record set in 2000.

Looking at individual countries, 2012 was the wettest year on record for England, third wettest for Wales, 17th wettest for Scotland and 40th wettest for Northern Ireland.

This adds to a high frequency of wet years since 2000 in the UK – with four of the top five wettest years occurring since then.

Top five wettest years in the UK
1. 2000 – 1337.3mm
2. 2012 – 1330.7mm
3. 1954 – 1309.1 mm
4. 2008 – 1295.0mm
5. 2002 – 1283.7mm

We have always seen a great deal of variability in UK rainfall because our weather patterns are constantly changing. However, preliminary evidence suggests we are getting slightly more rain in total and it may be falling in more intense bursts.

Looking at annual rainfall for the UK, we can see the country as a whole getting wetter in recent decades.

Long-term averages of 30-year periods show an increase in annual rainfall of about 5% from 1961-1990 to 1981-2010:

Annual average UK rainfall according to 30-year averages
1961-1990: 1100.6mm
1971-2000: 1126.1mm
1981-2010: 1154.0mm

Preliminary research from the Met Office also suggests we may have seen a change in the nature of the rain we get, with ‘extreme’ rainfall becoming more frequent.

An analysis of 1 in 100 day rainfall events since 1960 indicates these ‘extreme’ days of rainfall may have become more frequent over time.

The above graphic shows the frequency of what climate averages tell us should be roughly 1 in 100 day heavy rainfall events in each year. Over time, this gives a view of the frequency of ‘extreme’ rainfall.

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2012 Provisional stats
	Mean temperature ( °C)		Sunshine duration (Hours)		Precipitation (mm)
	Actual	Difference from 1981-2010 average	Actual	% of 1981-2010 average	Actual	% of 1981-2010 average
Regions
UK	8.8	-0.1	1356.4	99	1330.7	115
England	9.6	-0.1	1470.2	98	1123.2	131
Wales	9.1	0	1355.7	97	1716.2	118
Scotland	7.3	-0.1	1187.6	100	1602.6	102
N Ireland	8.9	0	1239.1	99	1153.7	102
England & Wales	9.5	-0.1	1454.4	98	1205	128
England N	8.8	-0.1	1360	99	1288.1	133
England S	10	-0.1	1528.5	98	1036	130
Districts
Scotland N	6.9	-0.2	1124.9	104	1599.5	93
Scotland E	7.1	-0.1	1217.1	96	1313.2	111
Scotland W	8.1	0	1239.1	99	1917.1	107
Eng E & NE	8.8	-0.1	1420.3	100	1064	137
Eng NW & Wales N	8.8	-0.1	1305	97	1614.1	122
Midlands	9.4	-0.1	1439.2	100	1074.6	135
East Anglia	10.1	-0.1	1538.1	98	804.1	129
Eng SW & Wales S	9.8	-0.1	1457.3	96	1574	125
Eng SE & Central S	10.3	-0.1	1601.5	98	999.7	127

Is 2012 the wettest year on record?

We announced last week that 2012 is already the wettest year for England in our records dating back to 1910, but we’re still waiting to hear whether it’s the wettest on record for the UK.

The latest figures we have for 2012 go from 1 January to 26 December, and show that during that time we’ve had 1291.2 mm of rain for the UK – meaning it is currently the 4^th wettest year on record.

It’s 46.1 mm short of the record of 1337.3 mm, set in 2000, so if 46.2 mm of rain falls between 27-31 December we will have a new record.

It’s likely to be fairly close-run, but it’s impossible to say whether 2012 is a UK record for rainfall until all the data come in from our weather observation sites around the country.

This information should come in on the 1^st and 2^nd of January, then all the data will need to be processed and we expect to have a provisional answer on Thursday, 3^rd January.

We’ll post the news here on our blog as soon as all the provisional statistics for 2012 come in.

Infographic: 2012 weather review of the year

Hover over the image to link through to more detail on the UK weather in 2012.

Weather forecasts for the Olympic Games

The Met Office is providing weather forecasts for all Olympic venues during the Games and beyond. As part of the services provided for London 2012, we have installed additional weather observation equipment and developed enhanced forecasting capability to support our staff.

During the Olympic and Paralympic games the Met Office will also be showcasing some cutting-edge weather techniques and technology in its forecasting, as well as providing additional services for the public. To add specialist knowledge and expertise, the Met Office will have 12 forecasters on site across the Olympic venues throughout the games.

For easy access to the latest forecast for each sport and Olympic venue, all the links you need are below.

Sports
Archery	Cycling – Mountain bike	Marathon swimming
Athletics	Cycling – Road	Rowing
Beach Volleyball	Equestrian	Sailing
Canoe Slalom	Football	Shooting
Canoe Sprint	Hockey	Tennis
Cycling – BMX	Modern Pentathlon	Triathlon

Locations
Olympic Park	North Greenwich Arena	Horse Guards Parade
Lords Cricket Ground	ExCel centre	Lee Valley White Water Centre
Wembley Arena	Eton Dorney	Hadleigh Farm, Essex
The Mall	Box Hill	Hampton Court Palace
City of Coventry Stadium	Hampden Park, Glasgow	Millennium Stadium
Old Trafford	St James’ Park, Newcastle	Hyde Park
Weymouth & Portland	Royal Artillery Barracks	Wimbledon

If you’re lucky enough to be attending an Olympic or Paralympic event, you can keep up to date with the local forecast while you’re there on our mobile applications for iPhone and Android, or on our mobile website.

Improving picture as many start school holidays

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?

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.”

First half of July continues wet and gloomy theme

Provisional mid-month statistics from the Met Office show that, after an exceptionally wet and gloomy June, the first half of July has continued the disappointing theme.

Normally at the halfway stage of a month we’d expect sunshine and rainfall to be somewhere around 50% of the average for the whole month, but the figures show a very different story.

Looking at the UK, we’ve already had more than the average rainfall we’d expect for the entire month – with 71.8mm (103% of the 1971-2000 average) falling up to the 15^th of the month.

Within that there are some big variations, however. Northern Ireland and Scotland have seen close to normal levels of rain, with 35.9mm (49%) and 56.4mm (61%) respectively. England and Wales have seen much more relative to their monthly averages, with 81.2mm (150%) and 95.8mm (122%) respectively.

Looking in even more detail at Scotland, however, you can see bigger variations in rainfall patterns: Mid Lothianshire in south east Scotland has seen 105.8mm (167%) of rain, while the Western Isles in the far north west of Scotland have seen just 10mm (10%).

This illustrates how rainfall patterns have really bucked their usual trend, with the far north west – which is usually one of the wettest places in the UK – continuing to be one of the driest areas. This is partly due to the position of the jet stream, as discussed in previous articles.

Looking at sunshine, there is a more consistent pattern across the regions. The UK has seen 45.5 hours of sunshine, just 26% of the average for the whole month, so around half what we would normally expect to see by this time. So far, England, Wales, Scotland and Northern Ireland have all seen about a quarter to a third of their monthly quota – making for a very dull month thus far.

Temperatures have also been on the disappointing side – with the UK seeing an average temperature so far of 13.7 deg C, which is 1.1 deg C below the monthly average.

With figures only going up to the 15^th of the month, it is of course impossible to say how the month could finish overall. It’s certainly too early to say whether this month will be a record-breaker, as that will depend on how the second half of the month plays out.

While more rain is expected in parts of the UK today there will also be some dry and sunny weather too.  The good news is that the weekend is set to bring drier and brighter weather to many parts of England and Wales – while the far north west of Scotland is likely to see some much-needed rain.

Are you holding a Diamond Jubilee event? Add it to our map

Are you holding a Jubilee Big Lunch event? We’d like to include your event on our Diamond Jubilee weather map on our website.

To submit your event, please add your event on our Facebook poll. Once you’ve added your event, ask your friends to vote for your event. The ten events with the most votes will be added to our event page and map. You have until 4 pm Friday 18 May to add your event to our poll.

Met Office in the Media: 8 January 2011

Snowy weather pushed north across parts of the UK yesterday bringing snow to some areas as expected.  The snow was fairly temporary for many as rain followed and tended to melt the snow that had fallen.  Overnight snow fell across parts of southern and eastern Scotland, leading to the closure of Edinburgh airport, with 7cm recorded at Edinburgh and as much as 10cm across other parts of eastern Scotland.

We had issued severe weather warnings of heavy snow for several Scottish regions, including Grampian, Strathclyde, Central, Tayside and Fife, south-west Scotland and Lothian and Borders.  Further falls of snow are expected across parts of Scotland through today.

Elsewhere across the UK, it is much milder, and the snow of yesterday has quickly thawed.

This snow is certainly not a return to the “big freeze” of last month and the sudden snow would “vanish as quickly as it arrived”, Helen Chivers, forecaster at the Met Office, said: “Really, it’s just normal wintry weather we’ve got over the next few days. As we go into next week, it’s going to be very much milder.” reports The Sun.

Elsewhere the Evening Standard has run a story suggesting the London Olympics in 2012 are at risk of being affected by a solar storm that could lead to problems with infrastructure.  This follows evidence the Met Office gave to the parliamentary Science and Technology sub-committee last October.  However the story has been reported rather dramatically.

The Met Office is not making any prediction that an intense solar storm, and associated disruption, will occur during the next solar cycle. Indeed, this sort of prediction is simply not possible for anyone to make this far ahead.

However, increased activity of solar storms is known to occur around or just after the solar maximum with the next expected around 2012 or 2013 and work directed by the Cabinet Office is underway to identify a properly reasonable scenario to inform the UK’s contingency planning.

Space weather is a relatively new science but understanding is growing rapidly and here at the Met Office we are building on our existing capabilities to develop a resilient operational warning service. We are working with the NOAA Space Weather Prediction Centre in the US to enable both organisations to advance the science more rapidly, to accelerate the development of improved models and space weather.