Will summer be a washout or a scorcher?

The Met Office has recently released its contingency planners’ outlook covering the period for June, July and August, with some sources suggesting this is predicting a summer heatwave.

But what does this early look at what might be in store for the summer actually say?

This summer, long-range weather systems show a slight increase in the chance of high pressure patterns across the UK and with this we see an increase in the chance of above-average temperatures. The point about the seasonal outlook, however, is that it gives us the more likely trends within the coming season.  As a result, below-average temperatures, although less likely, remain a realistic possibility.  A summer in which temperatures are more frequently slightly above average is the most likely scenario at this stage, but the fact that warmer and cooler outcomes than this are possible is a feature of the kind of information we are dealing with in long-range forecasting .

The outlook also gives an increase in the likelihood of drier-than-average conditions.  The summer period is one of the driest times of year across the UK; with rainfall coming in short, occasionally intense, showery rain affecting some places but leaving nearby locations dry. On balance, below-average rainfall is more likely than above-average rainfall.

Jeff Knight, manager of modelling of climate variability at the Met Office, said: “Our long term outlook for the summer suggests a greater chance that temperatures will be above average, than below average. However, our outlook certainly doesn’t imply a 3-month heatwave. As always with our climate there are likely to be large day-to-day and week-to-week variations the period. This is an outlook for the general themes over the summer and does not give detailed guidance on events like heatwaves.”

Perception of good weather is often more dependent on rainfall amounts than temperature. For example, even though the UK had a run of ‘poor’ summers between 2007 and 2012, half of these summers had temperatures above the long-term average. The long-range outlook is primarily aimed at giving government departments and agencies a forward view of potential weather hazards in the months ahead. As such, it is a risk assessment rather than a more traditional type of forecast of what the weather is going to be. Using evidence from global weather observations and computer forecast systems, we can estimate the chances of different types of UK weather and how they could be modified in the coming months.

When you look back at the average mean temperature for the UK  both 2017 and 2016 saw temperatures above the 13 C long-term average, with 14.5 C and 13.9 C respectively, and for summer as a whole the mean temperature was 14.7 C in 2017 and 14.9 C in 2016, both also above the long-term summer average of 14.4 C

You can find the current forecast on our website or mobile App or follow us on Twitter or Facebook, and as always our forecasts from one day to one month ahead can be relied upon to provide the best guidance on what to expect whatever weather patterns emerge.

Posted in Met Office News | Tagged , , , , , , , , , | 2 Comments

Met Office temperature records – what do we monitor and how far do they go back?

May saw more than its normal share of fine sunny days and notably high temperatures, reaching a peak of 28.7 Celsius at Northolt on 7th May to coincide with the early May bank holiday. That was just one place on one day. To get a broader picture we also look at the average temperatures across the whole month and all of the UK. The average daily maximum temperature in May was 17.2 Celsius. The persistent sun and warmth meant that this was the highest average maximum temperature on record for May.

But what does “highest maximum temperature for May” mean and how is it calculated? What types of temperature do we monitor, and how do they differ?

Daily Max Temp May

Average of daily maximum temperatures for May.  Setting a new record high for the national series.

 

Maximum, Minimum and Mean temperatures

All our standard temperature observations are made from the UK’s weather station network. Modern automated technology means we can actually track changes in temperature minute-by-minute. It hasn’t always been this way though, and historically it was not very practical to manually record the weather every minute of every day. Thankfully, British scientist James Six invented a maximum-minimum thermometer in the late 18th Century that could record the highest and lowest temperature recorded over a period of time. This invention allowed early weather observers to summarise the temperature of the day based on these two extremes, and the average of the maximum and minimum is widely used as an estimate of the mean temperature. This practice continues to this day, providing the UK with some very long records of the highs and lows of temperature across the country.

Daily Min Temp May

Average of daily minimum temperatures for May.  Ranked joint 10th warmest in the national series.

Station Records

The Met Office has routinely provided summaries of the monthly average of the maximum, minimum and mean temperature for the weather stations located throughout the UK since 1884. For a few stations we hold records going back much further. These station records provide an accurate picture of the month-to-month and year-to-year variations in temperature at particular locations. Our present-day observing network is comprised of over 400 stations.

Weather Observation network

Map showing the present-day weather observation network of automatic (blue) and manual (red) stations.

Find a selection of our historic station series here.

Central England Temperature records

The Central England Temperature (CET) series is the remarkable achievement of the scientist Gordon Manley. In the mid 20th Century Gordon Manley undertook painstaking research to uncover old weather records and diaries stretching back to the mid 17th Century and from these created the Central England Temperature series, providing an estimate of the monthly mean temperature of a region broadly representative of central England.

This work was continued by the Met Office to maintain a Central England Temperature record to this day, providing monthly mean temperature from 1659, daily mean temperatures from 1772, and separate maximum and minimum temperatures from 1878. The different start dates reflect the historical availability of the different types of observations.

The current CET series is, for historical consistency, comprised of observations from just three weather stations, forming a triangle encompassing roughly Lancashire, London and Bristol. This dataset is the longest of its kind in the world, and is an invaluable resource for investigating variations in our climate across several centuries.

However, the CET does not cover the whole of the UK or take full advantage of the complete network of several hundred weather stations currently monitoring weather across the whole country.  The CET series is available here.

National records

For most of the 20th and 21st Century we have had hundreds of observing stations across the UK recording maximum, minimum and mean temperatures. We could take a simple average of all of these observations to estimate a national average temperature. However, the precise number and distribution of stations across the country has changed over time, so a simple average is not the best way to estimate the national record. Instead we take a slightly more sophisticated approach. All available observations from a given date or month are interpolated to a uniform grid of points 5km by 5km covering all land areas of the UK. This gridding method also accounts for factors such as terrain height (mountain tops are cooler on average than lowlands), coasts (the sea can keep coastal areas cooler by day and warmer by night), and cities (the urban heat island effect means large cities are warmer than their rural surroundings). An average value is then calculated from the resulting grid of points. This approach provides the best estimate we have of national records.

There are currently sufficient temperature data on our computer archives for this gridding method back to 1910, providing over 100 years of national records for the UK, Scotland, England, Wales and Northern Ireland. So these records provide our official UK national climate series – the records that you will see quoted when the Met Office releases statistics.

The national and regional series from 1910 available to download here.

 

So what is the best measure of temperature for monitoring climate?

The answer is all of the above. The different types of data provide complementary information, all of which are routinely used to monitor UK climate and are published through the Met Office website each month.

Each of the maximum, minimum and mean temperature are all important in their own right for monitoring our climate and its extremes, and have all been observed for well over 100 years.

The national series derived from our gridded datasets from 1910 provide the most reliable estimates of UK-wide temperature, being based on all available station data. The CET series provide an invaluable and much longer climate series, providing a perspective of our climate for over 350 years. It is however based on a much more limited set of locations and stations. None of these records would be possible without the existence of high quality and long running historical station series. These station records provide observations for the site they are located in, but they are the firm foundations of our weather and climate observation heritage.

 

 

Posted in Met Office News | 6 Comments

Cyclone Mekunu closes in on Oman

In the two months prior to the onset of the Indian monsoon in early June, cyclones occasionally form in the North Indian Ocean. This year so far has seen the formation of two cyclones in the region – Sagar and Mekunu.

Cyclonic Storm Sagar formed in the entrance to the Gulf of Aden just over a week ago and unusually tracked along the length of the Gulf before eventually making landfall over Somalia, bringing heavy rain and flooding to northwestern parts of the country and neighbouring Djibouti.

No sooner had Sagar dissipated, another cyclonic storm developed and was named Mekunu. This cyclone formed some distance offshore in the Arabian Sea and has had several days to gather strength. Mekunu is now classified as a Very Severe Cyclonic Storm and is equivalent to a Category 2 hurricane. Mekunu is currently expected to make landfall close to the city of Salalah in southern Oman overnight Friday into Saturday UK time. Winds near 100 mph and 250-500 mm rain are possible, which is likely to cause damage to buildings and flash flooding. This region has an annual average rainfall of just 100-150 mm.

Cyclone Mekunu over the Arabian Sea on 24 May 2018

 

 

Cyclones of the strength of Mekunu have made landfall over the Arabian Peninsula in the recent past. In 2015 Cyclone Chapala brought flash flooding as it came ashore over Yemen. Cyclone Phet brought strong winds and heavy rain to northern Oman when it made landfall in 2010. The strongest cyclone on record to make landfall over the Arabian Peninsula was Gonu in 2007. This cyclone hit the far northeastern tip of Oman with winds in excess of 100 mph.

Mekunu will be making landfall over the central part of the Arabian Peninsula close to the border between Oman and Yemen. The historical record reveals that strong cyclones over this part of the peninsula are relatively rare. The most recent strong cyclones to make landfall close to the city of Salalah occurred in 1963 and 1959. The former produced over 200 mm rain and caused severe sandstorms. The latter caused flooding and severe damage to buildings.

Further Information

Official warnings for the latest tropical cyclones in the North Indian are issued by the India Meteorological Department. The Met Office routinely supplies predictions of cyclone tracks from its global forecast model to regional meteorological centres worldwide, which are used along with guidance from other models in the production of forecasts and guidance. We also provide updates on current tropical storms via @metofficestorms on Twitter.

Posted in Met Office News | Tagged , , , , | Leave a comment

A spring freeze and a bank holiday to please

It’s a testament to how often British Bank Holidays disappoint that, in the 40 years since it was introduced, temperatures had never exceeded 23.6 C on the early May Bank Holiday Monday.

At least, not until this year, says Aidan McGivern – a Met Office senior weather presenter.

This year, the usual Bank Holiday washout script was torn up and re-written. Rainclouds were replaced with sunshine. Records were broken, when 28.7 °C was reached in Northolt, West London: the previous top temperature was beaten by more than five degrees.

For any Bank Holiday beach-goers roasting in the afternoon sunshine, it may have been hard to believe that just two months earlier large parts of the UK were blanketed in deep snow.

Hard to believe, that is, until they took a dip in the toe-numbing waters. At just 12 °C around southwest coasts and 8 °C close to the northeast, the seas were still recovering from March’s Siberian winds.

Beast from the East part one, at the beginning of the month, brought sustained and brutal cold to every part of the UK from the Isles of Scilly to Shetland.  Tredegar in Wales recorded a maximum temperature on the 1st March of just -4.7 C, making it the coldest spring day in records that stretch back to 1910. Add into the mix a raw, easterly wind and many places felt a chill akin to the minus double digits.

Two rare Met Office red warnings were issued for disruptive snowfall in parts of Scotland as well as Wales and the South West between 28th February and 1st March. The snow stranded one-thousand vehicles overnight on the M80 and drivers were also stuck on roads such as the A38 and A30 in Devon.

Beast from the East part two swept across the country in mid-March and brought a return to sub-zero temperatures, icy winds and further disruptive snowfall in places.

Little wonder the seas remain so chilly in May. The air temperature may have switched from record-breaking cold to record-breaking heat in just two months but the sea has warmed sluggishly.

Water is a relatively slow conductor of heat. This means that, combined with the continuous moving and mixing of water molecules, it takes much longer for the sea to warm in spring and summer compared to the land. However, water also stays warm for longer – leading to a delay in cooling during autumn and winter.

These lag effects in warming and cooling can lead to a sea temperature frequently at odds with the surrounding air temperature from season to season. It’s also why the UK, a small island nation surrounded by seas, doesn’t often experience extremes of temperature.

The largest expanse of water near our shores lies to the west in the form of the Atlantic Ocean and that’s where our weather comes from much of the time. The jet stream, a ribbon of fast-flowing air high in the sky, tends to act as an atmospheric conveyor belt. Low-pressure systems form over the Atlantic and are carried towards the British Isles by the jet stream above, which typically flows from west to east.

When the jet stream is strong, we receive a full complement of cloud, wind and rain from the west. Atlantic weather, as well as being blustery and damp, acts as the UK’s thermostat, keeping us in mild winters and cool summers.

At times during Spring 2018, however, this moderating influence has been notably absent, resulting in some exceptional weather. A particularly dominant area of high pressure built up over Scandinavia during March. Known as a blocking anticyclone, this Scandinavian High held off the usual Atlantic westerlies and sent Siberian easterlies towards the UK. Beast from the East arrived – not once, but twice.

Fast forward to the early May Bank Holiday weekend and we encountered another blocking anticyclone lodged to the east of the British Isles. Once again, Atlantic winds en route to the UK were stopped. This time, however, Siberian winds had lost their bite. By May, winds from the continent tend to be warm and sunny.

Record-breaking cold early in spring followed by record-breaking heat later in the season; two very different outcomes but both the result of a Scandinavian High. However, whilst a blocking anticyclone can disrupt the eastward-moving jet stream, a weakened jet stream is ultimately responsible for the formation of blocking anticyclones. This ‘chicken and egg’ scenario illustrates just how complex and interconnected global weather patterns can be.

In fact, it’s during spring in particular that we are most likely to find blocking anticyclones and weakened jet streams. The jet stream is fuelled by temperature contrasts across the Northern Hemisphere and during spring these contrasts decline as continents warm but oceans remain cool.

For that reason, it’s not unusual at this time of year to find slow, meandering jet streams, blocking anticyclones, and continental-style swings in temperature in the UK.

The causes of Spring 2018’s particularly pronounced cold and hot spells are complex and varied. March’s Siberian easterlies were a response to a dramatic wind reversal 80,000 feet above the North Pole in the Stratosphere. This itself can be traced back to lively thunderstorms in the tropical West Pacific during January, which produced energetic reverberations high in the atmosphere throughout the Northern Hemisphere.

This year’s warm Bank Holiday Monday is more likely to be a quirk of fate. After all, particularly warm temperatures during early May are not unheard of, they’ve just never coincided before with the early May Bank Holiday Monday. It’s only taken 40 years for our fortunes to change.

 

Posted in Met Office News | Leave a comment

Scotland highlights weather contrasts during the first half of April

So far April’s weather is highlighting a month of contrasts, and perhaps nowhere is this contrast more apparent than in Scotland.

Between 1-15 April, parts of Scotland have seen both the most and least rainfall of any station in the UK, when compared with the long-term average (1981-2010).

The Edinburgh Botanic Gardens have so far received 63.4mm, which is equivalent to more than one and a half times the full month average for April (156%). Meanwhile, Loch Glascarnoch – in the north-west Highlands – has only received 12mm of rainfall, making it the driest location in the UK for the first half of April. This is equivalent to only 13% of the site’s monthly total rainfall. Elsewhere most of England and Wales have had a relatively wet start to April with some areas in the north east already at or above the average full month rainfall for April.

Much of the UK has had a dull start to April with hours of bright sunshine rather low for the time of year. The sunniest places have actually been in the far north and west of Scotland with Stornoway Airport observations showing that the site received 83 hours of sunshine in the first half of April, making it the sunniest place in the UK. In contrast, the weather station at Glasgow Bishopton has only received 20 hours: well below average and making it the dullest place in the UK so far this month.

Temperatures have generally been below average for April during the day, but night-time minima have been above average for most of southern England and Wales. Dr Mark McCarthy is the head of the Met Office’s National Climate Information Centre. He explains: “When you drill down in to the detail of the temperature records, you can see that cloudy and wet conditions have exerted a strong influence on the month’s climate records. Helping to supress daytime maximum temperatures, while the same cloud over night has an insulating effect, helping to keep night-time temperatures elevated.”

Provisional climate statistics for the first half of April.

Maximum Temperature Minimum Temperature Mean Temperature
Act °C Anom Act °C Anom Act °C Anom
UK 10.2 -1.3 3.9 0.5 6.9 -0.5
England 11.3 -1.2 4.9 1 8 -0.2
Wales 10.9 -0.7 4.3 0.6 7.5 -0.1
Scotland 8.2 -1.5 2.1 -0.3 5 -1
N Ireland 9.6 -1.9 3.9 0.2 6.6 -1
Precipitation Sunshine
Act mm Anom % Act hours Anom %
UK 52 72 41.8 28
England 51.7 88 35.9 23
Wales 71 80 40.7 26
Scotland 48.2 53 53.4 40
N Ireland 47.7 64 33.1 23

 

Posted in Met Office News | 2 Comments

100 years of women in public service – past, present and future

Earlier this year a Suffrage Flag began travelling around the UK to government departments and agencies to increase national awareness and mark the 100 years since women got the right to vote. We were delighted to host the flag at our head office in Exeter today.

We received the flag yesterday afternoon from the Environment Agency and it spent the night in the Flood Forecasting Centre, a partnership between our two organisations. Our Suffrage Flag event then started in earnest this morning, with speeches by our Director of IT, Charlie Ewen, and Strategic Relationship Manager Rebecca Hemingway.

The flag was raised by weather balloon and marked the start of our Equali-tea, a family-friendly event for our staff and their guests, with opportunities to learn about and discuss women’s suffrage, inspirational women and the importance of diversity.

Met Office staff at front-line stations also held Equali-teas to join in with the celebrations. Attendees had a go at making their own sashes, rosettes and banners highlighting challenges for democracy and hopes for inclusivity and diversity (and some demands for more cake).

The event ended as we handed the flag on to Exeter City Council. In a look to the future and as a reminder of the ongoing importance of ensuring equality and diversity, we invited local children to conduct the handover.

Take a look at our photo gallery below to see some of the events of the past couple of days.

Met Office interim Chief Executive, Nick Jobling, receives the flag from Environment Agency staff including Chair Emma Howard Boyd.

Met Office Director of IT, Charlie Ewen, launches our Suffrage Flag event.

Posted in Met Office News | 4 Comments

Weather ready, Climate smart

Weather-Ready, Climate-Smart’ is the theme for World Meteorological Day being marked around the globe today.

As the UK’s national meteorological service, we’re at the forefront of weather and climate science, with wide-ranging capabilities and areas of cutting edge expertise used to support the World Meteorological Organization (WMO) and meteorological services around the globe.

Weather-ready

Ultimately, the Met Office is about keeping people safe. Our National Severe Weather Warning Service (NSWWS) is the flagship for both the public and those organisations that protect them, including national and local governments and the blue-light services. As well as helping individuals to decide whether they should travel or undertake an activity, we partner with emergency responders to plan ahead. It’s this proactive approach working together with the UK’s civil resilience community that helps protect life and property and ensure we are ‘weather ready’ during periods of severe weather like the recent heavy snow and cold temperatures.

From the first indications of a possible cold spell, highlighted to contingency planners at the end of January, to the NSWWS issued 5 days ahead of the first ‘beast from the east’, we issued over 300 briefings to the UK Government, Scottish Government and resilience groups around the country. The Met Office is operational 24/7, working around the clock helping both organisations and individuals prepare for extreme weather.

Climate-smart

The Met Office science programme performs world-class scientific research which is used to inspire, develop and deliver innovative weather and climate services. The science and advice we provide to Government, helps ensure policy and decision makers have up-to-date, robust evidence on which to base their decisions and is a key tool for building UK resilience in a changing climate.

Through our international work we help other countries develop climate services enabling them to build their own resilience, on both seasonal and long-term timescales. Increasingly, we assess and predict environmental risks, drawing together a thread that runs right through weather, climate and applied science, to deliver world-leading services. For example when assessing flooding risk, as we did in the National Flood Resilience Review (NFRR), we use model simulations to assess present-day risk, which then informs how that risk will change in future. This is all part of the ongoing challenge of translating weather and climate hazards into the impacts that matter for people, and is crucial to developing appropriate adaptation strategies.

Did you know?

Do you have any idea just how much work the Met Office does? We provide weather and climate-related services to the Armed Forces, other government departments, the public, civil aviation, shipping, industry, agriculture and commerce just to highlight a few areas.

Take a look at the infographic below, and download the interactive PDF to click on each tile to find out more.

World Met Day interactive PDF

World Met Day

World Meteorological Day takes place every year on 23 March and commemorates the coming into force on 23 March 1950 of the Convention establishing the World Meteorological Organization (WMO). It showcases the essential contribution of National Meteorological and Hydrological Services to the safety and wellbeing of society and is celebrated with activities around the world.

Posted in Met Office News | Tagged , , , , , , , , , , , , , | Leave a comment

Watch this space!

Sun

Space weather is just the environmental conditions in space that can have an effect on Earth.

The most recognisable and visible of these is arguably the auroras (Northern and Southern Lights). However, as well as these spectacular natural phenomena, space weather also represents a real threat to our day-to-day life on earth; it can have an impact upon national infrastructure, technology, and communication systems.

Introducing more observations to improve forecasting

The Met Office ability to forecast space weather is dependent on the observations of the Sun that we receive from satellites in space.  For terrestrial meteorology, we receive millions of observations, every hour, from ground-based equipment, satellites, aircraft and radiosondes. There are far fewer observations of the Sun’s activity.

A mission to launch a spacecraft to gather new observations of the sun is underway. The L5 mission, championed by the UK Space Agency, gives us an opportunity to improve space weather forecasting.  The Met Office is one of the organisations in the UK involved in the project.

Having more observations will enable us to monitor the Sun for solar flares and coronal mass ejections (CMEs) more effectively. CMEs are large bursts of plasma from the surface of the sun and can reach the Earth in 18-96 hours, depending on speed and direction. They can result in geomagnetic storms that disrupt national power grids and global satellite and navigation networks.

Why do observations from L5 matter?

L5 refers to the 5th Lagrange point of the Sun-Earth gravitational system. A Lagrange point is a point in space where the gravitational pull of two objects cancel out (in this case the Sun and Earth), resulting in gravitational equilibrium. Any spacecraft positioned at a Lagrange point would experience a stable orbit and remain in the same place relative to the Earth and Sun.

Currently the NOAA DSCOVR and NASA SOHO at the L1 point both provide observations for space weather forecasting, but additional observations from the L5 point would provide a unique perspective on the Sun-Earth system.

Given the potential impacts, knowing when a CME will reach Earth is crucial for reducing the impact on national infrastructure. Currently, with the satellite imagery available, determining the direction, speed and width of a CME accurately is challenging.  L5 observations would enable much better calculation of these factors and greatly increase the precision of CME arrival forecasting.

The UK plays an important role

It’s estimated a severe space weather event, could cost the UK as much as £4bn because of this it is on the Government’s National Risk Register. The cost of an event could be significantly reduced by more accurate forecasting. To support this aim, in 2016, the UK Space Agency committed €22 million, over 4 years, to ESA’s Space Situational Awareness (SSA) programme.  This investment will support the UK’s growing space sector, which is a core part of the government’s Industrial Strategy, which aims to bring together the UK’s world-class research base with business investment, ensuring we continue to develop the technologies and industries of the future.

Dr Graham Turnock, Chief Executive of the UK Space Agency, said:

“The UK is a world leader in providing space weather forecasts and this mission will help the Met Office’s Space Weather Operations Centre improve this further. It’s a great example of the value of our work as a member of ESA to science and industry in the UK.”

Three out of four teams developing the platforms and instruments to support the European Space Agency (ESA) L5 mission are from the UK.  Airbus UK will lead on developing the overall mission, with the focus on mission operations, the spacecraft platform, and on how this interfaces with the instruments. STFC RAL Space will lead the development of instruments to observe the sun and heliosphere and UCL Mullard Space Science Laboratory will lead the development of instruments to make measurements of the solar wind. OHB, from Germany, will lead the fourth consortium, aiming to develop a competing platform, with all proposals to be assessed by ESA. ESA is planning to select a final design for the spacecraft and its instruments based on the results of these studies, which are due in about 18 months.

Posted in Met Office News | Tagged , , , , , , , , , , , | Leave a comment

La Niña cools 2018 CO₂ forecast, but it will remain close to a record year

The Met Office has released its annual forecast of the rise in atmospheric carbon dioxide concentration for the coming year.

Carbon dioxide will continue to rise as a direct consequence of emissions from fossil fuel burning and deforestation. But, in 2018 the rise is predicted to be smaller than in the last two years due to the temporary effects of climate variability on natural carbon sinks – locations which can absorb more carbon than they release.

The La Niña event has involved a temporary cooling of ocean temperatures in the eastern Pacific Ocean and shifts in weather patterns around the globe, especially in the tropics. Generally cooler, wetter conditions in many places cause enhanced vegetation growth, drawing down more carbon dioxide from the atmosphere than usual.  While this is not enough to halt the rise in carbon dioxide concentrations resulting from human-caused emissions, it does slow the rise for a few months.

CO₂ graph at Mauna Loa

Forecast CO₂ concentrations at Mauna Loa over 2018 (orange), along with previous forecast concentrations for 2016 (blue) and 2017 (green) and Scripps Institute measurements (black).

The Met Office forecast relates specifically to carbon dioxide concentrations measured at the Mauna Loa observatory in Hawaii.  The forecast overlays Scripps Institute measurements. The average concentration at Mauna Loa in 2018 is forecast to be 2.29±0.59 parts per million (ppm) higher than in 2017.  This increase is slightly less than that seen last year, and much less than the record rise of 3.39ppm seen in 2016, which was successfully predicted by the Met Office.

Professor Richard Betts, who compiles the annual Met Office carbon dioxide forecast, said: “Although the forecast carbon dioxide rise in 2018 would be smaller than the last two years, it would still be higher than the rise seen nearly every year of the 20th Century since records began in the 1950s, because emissions from human activities have increased.”

As a result of this rise, the annual average carbon dioxide concentration at Mauna Loa is forecast to be 408.9±06 ppm.  As usual, the concentration will fluctuate over the year in response to carbon uptake by vegetation in the northern hemisphere summer growing season, followed by a release of carbon in the autumn.

The monthly average concentration is forecast to reach 412.2±0.6 ppm in May before dropping back down to 405.8 ± 0.6 ppm in September.

Table 1. Forecast monthly average CO₂ concentrations at Mauna Loa over 2018.

Month Forecast CO₂ concentration (ppm)
January 407.9
February 408.7
March 409.6
April 411.5
May 412.2
June 411.3
July 409.5
August 407.4
September 405.8
October 406.1
November 408.0
December 409.4

 

Posted in Met Office News | 2 Comments

Will cold conditions return?

With two cold events already this month bringing freezing conditions and snow to the UK, some are beginning to question whether there may be further cold weather this Easter.

Met Office long-range forecasting expert Jeff Knight said: “It is too early to say exactly what weather we will get at Easter, but long-range forecasts show a greater than usual chance of cold spells over Easter and into April. Northerly or easterly winds will need to compete with the increasingly strong spring sunshine and longer days, however. So, it is unlikely that any cold spells will be as severe as those recently. If the cold does return, snow is unlikely to be as disruptive as recent events in southern Britain.”

Zonal mean zonal wind speed at 60N (absolute value and anomaly)

This graphic shows the greater than average occurence of westerly winds (warmer colours) during January, and the dramatic switch to greater than average easterly winds (cooler colours) from mid February.

The pattern of easterly winds leading to the repeated freezing conditions, was triggered from the tropics at the beginning of February and then exacerbated by a Sudden Stratospheric Warming on 12 February. This atmospheric disturbance propagated downwards weakening westerly winds all the way into the lower atmosphere. As we have reported previously this warming had a major impact by decreasing the westerly wind speed by more than 200 km per hour. This allowed the creation of high -pressure centres developing over Scandinavia and the Russian Arctic. With the clockwise flow around areas of high pressure, this brought some very cold spells with air tracking all the way from Siberia.

The black line in the above graph dips below zero in February – aligning with Sudden Stratospheric Warming. It also shows that it dipped into zero values yesterday at the extreme right.

Observations now confirm there has been a second, less intense SSW event. The lower stratosphere was already disturbed and this new event is unlikely to add much extra to what was already there.

Professor Adam Scaife, Head of Long-range Forecasting, explained: “The February stratospheric warming incident weakened the Polar Vortex – high-altitude westerlies – and the jet stream, giving rise to the intense easterlies at the end of February.  Following a recovery in the first half of March, a second but less intense sudden stratospheric warming has just occurred consistent with the continuing risk of cold easterly winds.”

 

 

Posted in Met Office News | 1 Comment