Met Office Forecasting Experiment

27 07 2015

Forecasting the weather accurately relies on a combination of cutting edge forecasting models developed by our research scientists and the skill of interpreting these models by expert meteorologists.

We’ve recently completed a “Forecasting Experiment” which brought together our research and operational expertise for two weeks.

The aim of this was to intensively evaluate and develop our current and experimental models, forecasting techniques, new scientific products and the interaction between them. The overall aim was to evaluate our forecasting capability so we can identify ways to continue improving the way we do things.

Experts from a range of backgrounds analyse model output in the 'Forecast Experiment'

Experts from a range of backgrounds analyse model output in the ‘Forecast Experiment’

We have a number of computer models which can represent weather processes which occur on ever smaller scales.

These models cover different areas of the globe: from the entire world, down to a model which is confined to the UK area and even an experimental model which looks at the weather over an area the size of a large city.

All these models are incredibly complex and have strengths and weaknesses which can be difficult to determine.

By bringing together specialists with considerably different skills and experience in the Forecasting Experiment, it is easier to identify characteristics of the models. This can then inform better interpretation of all the information available to forecasters and can also help with planning improvements in future generations of the models.

The Forecasting Experiment this year was focused on summer weather over the UK. The experiment ran over the end of June and beginning of July.

The first week was characterised by a succession of weather fronts moving eastwards from the North Atlantic over the UK. The second week was dominated by very warm air from Spain moving north across the UK and bringing the hottest July day on record (36.7 °C at Heathrow) with severe thunderstorms to much of the UK, especially the North of England and Scotland.

This mixture of weather types allowed researchers to test models and techniques under a whole range of summer conditions, including high impact weather.

Adrian Semple,who led the experiment, said: “Not only did this experiment promote an exchange of skills, knowledge and experience between the participants, but it also provided a unique environment in which we could critically assess the way in which we produce our forecasts. The experiment will therefore have immediate effects as skills and knowledge are shared and spread throughout the Met Office, but the results can also be used to influence our longer term scientific research and improve future forecasting models.





Mixed bag for the start of June

17 06 2015

It has been a very varied weather picture so far this month.

It’s been dry and warm for the south east of the UK, with some places around London having received less than 5 mm of rainfall so far and areas such as Essex, Hertfordshire, Suffolk and Cambridgeshire receiving less than 20% of the month’s average in places.

This year’s highest UK temperature so far, 26.8 °C, occurred at Kew Gardens (Greater London) on the 12 June.

Much of the rest of the UK has seen temperatures in general noticeably below average for June, continuing on from the rather cool May.  While rainfall totals are already close to the whole-month average in the central Scottish Highlands and in Nottinghamshire.

MeanTemp June

June began with two very unseasonal days, due to a deep low-pressure system to the west of the UK, bringing large amounts of rain and some strong winds to the UK, particularly southern areas. Apart from this, and some showery rain on the 5th/6th,

June so far has been relatively settled, especially over southern areas, although we saw a period of thundery outbreaks on 12th June affecting mainly southern areas due to a plume of very humid and warm unstable air moving in from France/Spain.

Mean temperatures for the UK so far this month have been 2 °C below normal in most areas, but colder in the far north-west of the UK and a little closer to normal in southern England. While the minimum temperatures have been well below average, by as much as 3 °C over some northern areas.

mean temperature sunshine duration rainfall
1-15 June 2015 Act (°C) Diff from avg (°C) Act (hrs) % of avg Act (mm) % of avg
UK 11.2 -1.8 117.6 69 31.3 43
England 12.5 -1.6 128.3 70 23.1 37
Wales 11.6 -1.6 121.6 70 41.8 49
Scotland 9.3 -2.0 99.3 66 43.9 49
N Ireland 10.3 -2.5 114.3 76 21.4 28

We would expect figures to be around 50% of the average figures by the mid month point.

For the latest weather forecast go to www.metoffice.gov.uk/weather





Predictions of a below average Atlantic hurricane season

21 05 2015

The Met Office Atlantic tropical storm forecast for 2015 is for eight tropical storms between June and November, with a 70% chance (the ‘70% range’) that the number will be in the range six to ten. This is below-normal relative to the 1980–2010 average of 12 tropical storms.

The forecast number of hurricanes — tropical storms with winds of at least 74 mph — is five (70% range three to seven); the average number of hurricanes is six.

Tropical storm Ana on 8 May 2015 as it approached the South Carolina coast. Credit: NASA Earth Observatory

Tropical storm Ana on 8 May 2015 as it approached the South Carolina coast. Credit: NASA Earth Observatory

The forecast Accumulated Cyclone Energy (ACE) index — a measure of the strength and duration of storms over the season — is 74 (70% range 40 to 108); the average ACE index is 104.

The North Atlantic hurricane season typically runs from June to November, but has already seen one tropical storm (Ana) make landfall in South Carolina.

The evolution of the El Niño Southern Oscillation (ENSO) over the next few months will play a large part in the North Atlantic hurricane season.

Forecast centres around the world have now declared that an El Niño has begun in the tropical Pacific.

Joanne Camp, climate scientist at the Met Office, said: “El Niño conditions in the Pacific can hinder the development of tropical storms in the Atlantic, so how this develops will be important for the storm season ahead.”

While it is still too early to determine with confidence how strong this El Niño might be, forecast models from centres around the suggest this El Niño is likely to strengthen during the coming few months.

The tropical storm forecast is produced using the Met Office’s seasonal forecast system, GloSea5.

It has higher resolution than its predecessor, with better representation of the complex physical processes that cause tropical storm and hurricane development.

For regular updates on tropical cyclones worldwide follow @metofficestorms on Twitter.





Anniversary of the death of FitzRoy – founding father of the Met Office

30 04 2015
Vice Admiral Robert Fitzroy

Vice Admiral Robert Fitzroy

Today (30th April) is the 150th anniversary of the death of Vice Admiral Robert FitzRoy, the founder of the Met Office. FitzRoy joined the Navy when he was just 12 years old and made his name as commander of several ships including HMS Beagle, made famous by the voyages of Charles Darwin. FitzRoy met Darwin in 1831 inviting him aboard the Beagle, as a fellow gentleman, to keep him company during the long journey, thus changing the course of history forever. Today the voyage of the Beagle is synonymous with Darwin, however, as the ship’s captain, FitzRoy played a crucial role in the journey. FitzRoy became an MP during the 1840s and introduced a Bill dramatically improving safety at sea by introducing qualifications for ships masters and mates. FitzRoy continued to advance his naval career and was appointed Director of the Meteorological Office in 1854. The dawn of weather forecasting

First Daily Weather forecast, The Times, 1 Aug 1861

First Daily Weather forecast, The Times, 1 Aug 1861

Following the disastrous Royal Charter Storm of October 1859, FitzRoy lobbied for permission to establish a Gale Warning Service for the protection of shipping. Observations from stations around the British Isles were sent to London and gale warnings were issued when necessary. Using a system of cones and drums, the direction from which the gale would strike was displayed for ships both in port and passing along the coast. Possibly the first national forecasting and warning system in the world the service continues to this day as the ‘Shipping Forecast’. FitzRoy felt that ‘prediction’ and ‘foretelling’ sounded too unscientific for a process based on the developing science of meteorology so he coined the term ‘weather forecast’. His first public weather forecast, published in his own hand writing, was published in the Times on 1 August 1861. Although he had been given Government backing to establish a Gale Warning service, FitzRoy had no permission to establish public forecasts, nevertheless they were very popular. Queen Victoria used to contact FitzRoy for forecasts a few days before making journeys to Osborne House on the Isle of Wight. Indeed, on the last day he attended the office it was to telegraph a forecast to the Queen. Scientific and meteorological work FitzRoy felt strongly that not enough was done to protect the lives of sailors and fishermen and he devised a new barometer for use in fishing harbours.  They were placed where all could see them and were designed to be easy to read and interpret, FitzRoy’s barometers were credited with saving hundreds of lives and FitzRoy paid for many of them himself, exhausting his own personal fortune.  A few barometers survive in situ at fishing ports around the British Isles, including Mousehole in Cornwall. FitzRoy’s The Weather Book: A manual of practical meteorology, written during a Summer Holiday in 1863, was a leading work on meteorological science and techniques and marked the beginning of an era of major advances in meteorology and guided the science into the 20th century. Death and legacy FitzRoy was a pioneer of meteorology and forecasting and was, in many ways, a man ahead of his time. A workaholic who once declared, ‘I’d rather wear out than rust out’, FitzRoy increasingly struggled with depression.  The pressure of work and criticism took a severe toll on his health and, on 30 April 1865, FitzRoy took his own life. He was buried in unconsecrated ground within the front churchyard of All Saint’s Church, Upper Norwood. His entire fortune of £6,000 (equivalent to around £400,000 today) had been exhausted on public service. FitzRoy was the world’s first full-time weather forecaster. As a pioneering meteorologist and founding father of the Met Office, FitzRoy made accurate weather forecasting a reality. To this day, the Met Office is proud of this outstanding scientific legacy and strives to continue operating at the forefront of scientific discovery.





More warm weather this week – but what’s in store for the summer?

13 04 2015

This week is set to see some unseasonably warm weather for parts of the UK – with temperatures expected to climb to the low to mid-20s Celsius in the south on Tuesday and Wednesday.

Warm air flowing up from the south west will combine with high pressure, bringing settled conditions and sunny spells for many.

Warmest days of the year so far

This week’s above average temperatures follow on from a similar spell last week, which saw temperatures top out at 21.9C at St James’s Park in London on Friday.

This was the ‘warmest day of the year so far’, but It looks like Tuesday and Wednesday will top that – which is to be expected as we head through spring and edge closer to the start of summer.

Unfortunately, the weather we get in April doesn’t necessarily tell us anything about the kind of summer we can expect. We’re still in the midst of spring, so it’s far too early to say what the months of June, July and August may hold.

Summer ‘heatwave’ speculation

That hasn’t stopped speculation about heatwaves, the warmest summer ever and record temperatures in the media. Some stories cite our three month outlook for contingency planners as proof of the impending heatwave, but this is in no way an accurate reflection of what it shows.

The outlook shows probabilities attached to different scenarios for temperature and rainfall over the whole three-month period it covers. This is useful for those who use probabilities to plan ahead on longer-timescales, but not very useful for deciding where and when to go on your UK summer holiday, for example.

What does the longer outlook show?

Our current three month outlook does show that above average temperatures are more likely than below average temperatures for the April-June period. The outlook is essentially the scientific equivalent of factoring the odds on a horse race and, just like a horse race, the favourite doesn’t always win.

It’s also important to note that above average temperatures over a three-month period could come about in a variety of ways in terms of actual weather – we can still see warmer than average temperatures when it’s cloudy and wet, for example. Also, even in an above average three-months not all individual months would need to be above average.

This just reinforces the point that the contingency planners outlook doesn’t tell us what specific weather we are going to see at a specific location. For the best information on the weather ahead, people should use the Met Office’s 5-day weather forecast supplemented with our 30-day outlook.

By keeping up to date with the latest forecast, you’ll always have the most up-to-date and accurate view of the weather in store for the UK.





Air Quality Forecast

17 03 2015

Localised areas of Greater London are currently recording Moderate to High levels of air pollution. More widely across Eastern parts of the UK, Moderate levels of pollution are also being recorded. Due to the current weather conditions these levels are likely to remain Moderate to High in certain areas for the next 24 hours.

Although these conditions are going to be short-lived, and while the great majority of people will not be affected by short-term peaks in air pollution, some individuals, such as those with existing heart or lung conditions, may experience increased symptoms. Those vulnerable members of the public can find further information on health advice here.

The Met Office is working very closely with Defra and Public Health England to ensure they have the most up-to-date and accurate air quality forecasts in order to provide relevant advice to the public.

Current Weather Conditions

Throughout today and into tomorrow high pressure will continue to draw in air and pollutants from the continent which adds to the pollution building up in urban areas.

High pressure is also currently sitting to the East of the UK bringing us calm and settled weather allowing pollutants to become trapped close to the ground.

How long will it last?

From tomorrow morning the high pressure will move westwards across the UK and start to bring cleaner air from the North and North East Europe, which will start to disperse pollution. By the end of Thursday pollution levels across the UK should return to Low values.





Holiday Dust

24 02 2015

At this time of year, many of us are in search of some winter sun, and a popular destination for Brits abroad is Egypt.

Typical conditions in Cairo at this time of year are fairly warm, dry and sunny. On average in February you could expect to see daytime highs of 21C, 8 hours of sunshine per day, and 1 wet day in the whole month. However, there may be some disappointed holidaymakers at the moment, as rather than sunshine; there is dust in the forecast. A dense dust plume has been developing across Libya and Egypt and will continue to grow over the coming days.

A deep area of low pressure in the central Mediterranean has given some very unsettled weather over recent days, and will continue to bring heavy rain and snow to northern parts of Algeria, Tunisia and perhaps western parts of Libya over the next few days. Very strong winds around the low will generate dust storms and sand storms and these will move across the rest of Libya and into Egypt during the first part of this week.

The dust storms will be severe and widespread enough to cause some disruption to air travel in the region, with perhaps some public health issues also.

The deep pink area in this satellite picture is the dust, and the line of dust stretches right up towards Greece.

The deep pink area in this satellite picture is the dust, and the line of dust stretches right up towards Greece.

These intense dust storms are often called Haboobs, which were first named in Saharan Sudan. They are frequently associated with thunderstorms or even small tornadoes, and usually last about three hours. The storms tend to develop late in the day during summer, and are sometime followed by rain. They can transport and deposit huge quantities of sand or dust, moving as an extremely dense wall that can be up to 100 km wide and several kilometers high.

Dust storm

For more information about the weather abroad, visit our holiday weather section.





Two cyclones to hit Australia

19 02 2015

Whilst here in the UK, we are coming towards the end of our winter season, Australia is coming towards the end of summer, but is in the middle of its cyclone season, and unusually there are currently two tropical cyclones affecting the country.

Severe Tropical Cyclone Lam is currently to the north of Australia’s Northern Territory, in the Arafura Sea. The storm is expected to make landfall on Thursday as a category 4 storm, between Milingimbi and Gapuwiyak. Huge rainfall figures are forecast, with 300 to 600mm daily, potentially adding up to more than 800mm in places throughout the storm event, with flooding likely inland, as well as coastal flooding and damaging winds. Residents close to the coast have been advised to be ready to move to shelter with emergency kit. However, as the area is not densely populated, significant impacts are not expected. The nearest large population centre is Darwin, and although it is likely that there will be some wet and windy weather here, it is not expected to be anything that Darwinians aren’t used to.

Credit: Courtesy of the Naval Research Laboratory

Credit: Courtesy of the Naval Research Laboratory

Storm track and warning areas for Tropical Cyclone Lam

Storm track and warning areas for Tropical Cyclone Lam

Meanwhile, Severe Tropical Cyclone Marcia is heading towards the Queensland coast, and is expected to make landfall between Mackay and Gladstone on Thursday night as an extremely powerful category 5 storm. The Australian Bureau of Meteorology are forecasting Marcia to track inland for a while and quickly weaken, before turning parallel with the coast, which keeps the main risk area to the north of Brisbane. However, there is some uncertainty with the exact track of the storm, and if it were to remain closer to the coast, Brisbane could be in line for a significant amount of rainfall, potentially as much as 400mm. Destructive winds are likely around the coast and abnormally high tides will be experienced with water levels expected to rise above the highest tide of the year. Dangerous storm tides are forecast as the cyclone crosses the coast, as well as treacherous surf on exposed beaches.

Credit: Courtesy of the Naval Research Laboratory

Credit: Courtesy of the Naval Research Laboratory

Storm track and warning areas for Tropical Cyclone Marcia

Storm track and warning areas for Tropical Cyclone Marcia

Met Office StormTracker provides a mapped picture of tropical cyclones around the globe with access to track history and six-day forecast tracks for current tropical cyclones from the Met Office global forecast model and latest observed cloud cover and sea surface temperature. We also provide updates on current tropical storms via @metofficestorms on Twitter.





One year on – A look back to last winter

17 02 2015

This weekend marked the one-year anniversary of the Valentine’s Day storm, which also marked the end of a particularly stormy three-month period. A new review article – ‘From months to minutes – exploring the value of high-resolution rainfall observation and prediction during the UK winter storms of 2013/2014’ – written by 16 Met Office co-authors reviews the accuracy of our forecasting and warning of severe weather during winter 2013-14, and assesses its performance.

The paper concludes that the “prolonged period of high impact weather experienced in the United Kingdom during the winter of 2013/14 was very well forecast by the operational tools available across space and time scales.”

Here Huw Lewis, the paper’s lead author, and Derrick Ryall, Head of the Public Weather Service, look at the extreme weather last year and the role of the Met Office in communicating severe weather through the National Severe Weather Warning Service.

Analysis chart 1200 GMT 26 January 2014

Analysis chart 1200 GMT 26 January 2014

Winter 2013/2014 in the United Kingdom was remarkable. The country was battered by at least 12 major winter storms over a three month period and was officially assessed as the stormiest period that the United Kingdom has experienced for at least 20 years.

The series of storms resulted in the wettest winter in almost 250 years (according to the England and Wales precipitation series from 1766), significantly wetter than the previous wettest winter in 1914/1915.

Snapshot of UK rain radar surface rainfall rate for 2200 GMT on 23 December 2013

Snapshot of UK rain radar surface rainfall rate for 2200 GMT on 23 December 2013

The extreme weather caused widespread flooding throughout Southern England and coastal damage – most notably in the South West and Norfolk coasts. The impact of the severe winter storms on individuals, businesses and the government were substantial, including several fatalities, widespread power cuts and damaged infrastructure.

Recent advances in forecasting, technology and the scientific developments in meteorology have been considerable. These developments and improvements in accuracy mean that a four-day weather forecast is as accurate as a one-day forecast was just thirty years ago. During the course of last winter, the Met Office was able to use these forecasts to warn of any severe weather well in advance. In the case of the St Jude’s Day storm at the end of October 2013 warnings went out to the Government and the public five days before the storm even existed.

rainfall

As the accuracy of weather forecasts has evolved, so has the communication of the potential impacts of severe weather. The National Severe Weather Warning Service enables more ‘weather decisions’ which in turn help to minimise the consequences of severe weather. The Met Office was at the heart of the government response to the storms, providing advice on weather impacts through the National Severe Weather Warning Service and Civil Contingency Advisors. The Met Office also worked very closely with both the national and regional media, who in turn played a key role in ensuring that the public were fully informed about the potential impacts of any up-coming weather.

In addition to the Public Weather Service, commercial partners and customers were also provided with detailed updates throughout the period in order for them to plan effectively for logistical issues. Together, these advanced warnings helped authorities, businesses and individuals to be better prepared to take mitigating actions.

Driving further improvements in accuracy and therefore reducing the lead time and increasing the detail of severe weather warnings is one of the Met Office’s key priorities . The ultimate aim is to improve the potential for users to plan preventative measures for severe weather events much further ahead. Underpinning all of these developments is a continuing programme of scientific research and access to enhanced supercomputing over the next few years.





Untangling the global drivers of UK winter weather

25 11 2014

As we head towards the start of winter, which starts for meteorologists on 1 December, there’s always a great deal of media and public speculation about what weather we might have in store.

To answer that question, we need to look beyond the UK. The worlds’ weather is interconnected, and there are certain large scale global drivers which we know have influences on UK weather at this time of year – so what are these doing at the moment?

El Niño, which sees unusually warm sea surface temperatures across the tropical Pacific and can increase the risk of cold winter conditions in the UK, has been much discussed after initial signs of development earlier this year.

Its progress has been slow, however, and while there remains a good chance of a weak event by the end of the year it is also possible that El Niño conditions will remain neutral. In any case, this factor is not expected to be strong enough to exert much influence on weather patterns in Europe during the next three months.

The North Atlantic Oscillation (NAO) describes differences in the usual pressure patterns over the North Atlantic – with positive and negative phases.

A positive phase is thought more likely than a negative one on average over the next three months. This is characterised by enhancement of the westerly winds across the Atlantic which, during winter, brings above-average temperatures and rainfall to Western Europe.

As we head later into winter, confidence about the heightened likelihood of positive NAO reduces – suggesting chances of drier and colder conditions return closer to normal.

The Quasi-Biennial Oscillation (QBO) sees high level (stratospheric) winds over the equator change from westerly to easterly phases – and it’s currently in the latter of the two.

In winter months this can lead to a greater incidence of high pressure blocking patterns over the northern hemisphere, which would increase the probability of colder and drier weather across Europe. Essentially this is providing an opposite signal to the NAO.

There are other factors to consider too. For example, Arctic sea ice extent is slightly below average but as yet it is not clear whether this might have an impact on weather patterns in the UK.

No single one of these drivers will determine the UK’s winter on its own – instead they all interact together to govern the weather trends we can expect over the coming months.

Disentangling these different influences remains a challenging area of science which the Met Office is improving all the time, but detailed and highly certain UK outlooks are not possible over these timescales.

The Met Office’s long-range outlooks give probabilities based on scenarios of being considerably wetter or drier, colder or milder than usual.

Currently the outlook for December 2014 to February 2015 suggests that milder and wetter than average winter conditions are slightly more likely than other outcomes. However, compared to day-to-day weather forecasts, the probabilities are much more finely balanced – for example, the outlook gives a 1 in 4 chance of the mildest scenario and a 1 in 10 chance of the coldest scenario. These numbers suggest it would be a mistake to interpret the outlook for a very mild outcome as ‘highly likely’; likewise very cold conditions cannot be ruled out.

The outlook gives similar probabilities for precipitation (rain, hail, sleet and snow), with the chances of the wettest scenario being 1 in 4 and the chances of the driest around 1 in 10.

These three month outlooks cover a whole three month period, taking into account both day and night, as well as the whole of the UK. This means that even in the event of, say, an overall mild winter we could still see spells of cold or very cold weather.

With this in mind, what exactly we’ll see for the winter ahead remains uncertain. In terms of strong winds, heavy rainfall, cold snaps or even snow, while longer-range outlooks can give us general tendencies, the details can only be predicted by our day-to-day weather forecasts.

The Met Office’s accuracy over all timescales is world-leading, however, so you can trust that we’ll keep everyone up-to-date with all the latest information on the weather whatever the winter has in store.








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