A tale of two halves for February and winter

28 02 2012

As February and winter draw to a close, early statistics show that both have been stories of two halves.

We often talk about why you can’t pre-judge a month or a season at its half-way stage, and the latest figures perfectly illustrate why that’s the case.

The mean temperature for the first half of February was very low as cold weather gripped the UK – particularly in England where temperatures were 4 °C colder than the long term (1971-2000) average.

If you’d projected those figures out to the end of the month you would have expected one of the coldest Februarys on record.

However, the second half of the month (figures go up 26 February) has seen some exceptionally mild weather to balance things out and we have ended up with a rather average month for overall UK mean temperature which so far, was just 0.1 °C above average.

This story of two halves can be seen in the maps below, with the blue colours denoting lower than average temperatures in the half-month figures on the left, and the more balanced situation by the end of the month on the right.

Winter, which meteorologically speaking runs from December to February, has been a fairly similar story – but in reverse.

A mild December and first half of January meant we had a very mild first half of the season, which led to some media headlines mooting one of the mildest winters on record.

However, the last few days of January and the first half of February were colder than average, bringing the overall temperature for the season down.

With a couple of days still to go, the early statistics show the UK’s mean temperature for winter is 0.7 C above average, making this a mild winter – comparable with several other mild winters in the last decade.

One common theme between this February and winter as a whole is dry weather – particularly for the south and east of the UK.

February was particularly dry, with the UK having seen just 62% of the normal amount of rainfall we’d expect for the whole month by the 26th. With a few days left, this is unlikely to change by much.

England was the driest country, having so far seen just 43% of the rainfall we’d expect for the month and Wales not far behind at 49%.

Winter has also been dry overall in England, with just 82% of the rainfall expected for the season and Wales has seen 89%. This is slightly balanced out in the statistics by Scotland being wetter than normal over the season, seeing 116% of its normal rainfall.

The relative lack of rainfall for February and the season as a whole can be seen in the two maps below, with the brown colours denoting drier than average weather for the month on the left and for the season on the right.





Warmest February day since 1998

24 02 2012

Yesterday saw many parts of the UK enjoying sunshine and exceptionally mild weather for the time of year.

The highest temperature recorded yesterday was 18.7 °C at Coleshill, Warwickshire, making this the warmest February day in the UK since 1998.

Here is a selection of yesterday’s high temperatures around the UK:

18.7 °C Coleshill, Warwickshire
18.3 °C Market Bosworth, Leicestershire
18.2 °C Santon Downham, Suffolk
18.2 °C Shoeburyness, Essex
17.6 °C Donna Nook, Lincolnshire
17.1 °C Kew Gardens, London
16.7 °C Hawarden, Flintshire
15.9 °C Dyce, Aberdeen
15.1 °C Killowen, Newry and Mourne

The mild weather is set to continue into next week, with the best of the sunshine and the highest temperatures always likely in central and eastern parts of England and eastern Scotland. It will feel pleasant in any sunshine but we can expect some cold nights over the weekend, with a touch of frost around on Sunday morning.





Met Office in the Media: 22 February 2012

22 02 2012

There is some mild weather for the time of year on its way tomorrow with temperatures climbing to the mid teens across the UK. Some newspapers, such as The Sun, the Daily Mail and the Daily Express,  have been suggesting that the UK will be warmer than Hawaii tomorrow. Although this would be very nice, I am afraid to say this is not quite true, with temperatures in Honolulu predicted to be up to 26 deg C on Thursday.

Although it will be mild for many, it will still be mainly cloudy with further light rain in the west. Some mist and fog is also likely across western coasts and hills. The best chance of bright or sunny spells developing will be to the east of country, especially in the shelter of hills. Where the sun comes out, temperatures are likely to be very mild for late winter.

Top temperatures on Thursday are expected to be around 16 or 17 deg C in parts of central and eastern England, while  Scotland is likely to see its warmest spots in the east, where it could reach up to 15 deg C.

So, although Thursday will be a very mild day for the time of year and while some places may see some bright spells, it certainly will not be wall to wall sunshine. Unfortunately, it will also be nothing like Hawaii – more like a mild, pleasant late winter day in the UK.

The mild temperatures fall away a little as we head into Friday and the weekend as rain sinks south on Friday, with brighter, colder conditions to the north. Most places are expected to be dry on Saturday but rain is likely to return to western parts later in the day and on Sunday.

Forecast maximum temperature ranges for the next 5 days for Manchester from the Met Office beta website

Elsewhere there has been widespread coverage of the findings of the Science and Technology report on The Science of the Met Office which endorsed the trust the nation has in the Met Office to provide forecasts and warnings when it matters. Coverage has focused on the reports recommendations for additional computer resource at the Met Office. We welcome the committee’s recommendation; all witnesses highlighted the significant socio-economic benefits which could be gained from increased supercomputer capacity. Increased supercomputing resource would enable existing research findings to be used in the creation of weather and climate predictions, helping to improve the accuracy, reliability and relevance of forecasts on all timescales

However, it is important to recognise that funding for additional supercomputing resource has not been secured and the figures in the S&T committee report are purely recommendations. The Government recognises the importance and value of investment in supercomputing capacity to improve weather and climate modelling. We will continue to work closely with BIS and other stakeholders across Government, to support the development of the business case for the next generation of supercomputing capacity.

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Has spring sprung?

21 02 2012

This week temperatures are forecast to reach 16 °C, the mildest of the year so far. This is unseasonably warm for February, which usually reaches highs of around 8 °C on average.

So is this the first sign of spring? Meteorologically speaking, no. For statistical purposes in meteorology, spring begins on the 1 March and ends on the 31 May. For many people though, spring begins on the date of the spring equinox, 20 March.

Although spring can be determined by calendar dates, the natural variability within the atmosphere means that, as far as the weather is concerned, year to year differences vary widely.

However, looking beyond the year to year differences we see that our climate is changing, records show spring has advanced 2-6 days per decade in the UK. Those with gardens need to start cutting their lawns almost two weeks earlier than they did in 2001.

Research undertaken by the Met Office Hadley Centre has also confirmed that the growing season of plants is likely to increase by around 40 days by 2080, due to the earlier start to spring and later end to autumn.

The mild but wet and windy weather is set to continue until the weekend, visit the website for your local forecast.





Met Office recognised as world-leading by Science and Technology Select Committee

21 02 2012

The Met Office welcomes that the Science and Technology Committee recognises the Met Office fulfils its role as the national weather forecasting service for the UK and is underpinned by a robust science strategy that delivers a cost effective and accurate service for the UK and beyond.

John Hirst, Met Office Chief Executive said: “This endorsement from the Science and Technology Committee affirms the trust the nation has in the Met Office to provide forecasts and warnings when it matters.”

During the course of the review, the committee heard about the importance of the Met Office’s role in providing vital services for the UK and our world-class science. The Met Office is unique, combining world-leading science and operational infrastructure that supports us to ‘pull through’ our science to provide ever better forecasts and warnings.

Julia Slingo, Met Office Chief Scientist said: “I am delighted that it has been recognised that the Met Office science strategy has been very well received across the meteorological community. It provides a robust and cost-effective platform for the ‘pull through’ of our science for the benefit of the UK”

The Science and Technology Committee identified the need for additional supercomputing resource. We welcome the committee’s recommendation that further investment would be of value.

However, it is important to recognise that the Met Office has currently not secured any funding for additional supercomputing resource and the figures in the Science and Technology Committee report are purely recommendations.

The Government recognises the importance and value of investment in supercomputing capacity to improve weather and climate modelling. BIS, working closely with the Met Office and other stakeholders across Government, will continue to develop the business case for the next generation of supercomputing capacity.

In the mean time we will continue to provide the world-class forecasts the British public and our customers have come to expect.

Science and Technology Committee Thirteenth Report – Science in the Met Office

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What is ‘feels like’ temperature?

15 02 2012

Have you ever stepped out of the house in the morning and thought I know it would be cold, but perhaps not this cold!

The temperatures that you normally see on our website represent the temperature of the air, but this takes no account of how we actually experience the temperature. It is our ‘feels like’ temperature that gives you a better idea about how the weather will actually feel when you step outdoors.

Our ‘feels like’ temperature takes into account wind speeds and humidity to assess how the human body actually feels temperature.  For example in winter a strong wind can feel much colder than the measured temperature would indicate. Conversely on a humid day in summer it can feel uncomfortably hotter than the air temperatures would suggest on their own. In both instances the impacts of the temperature, wind and humidity can be much greater and the feels like temperature should allow users to make a better assessment of conditions outdoors.

But how do you actually calculate the ‘feels like’ temperature?

We calculate a ‘feels like temperature by taking into account the expected air temperature, relative humidity and the strength of the wind at around 5 feet (the typical height of an human face) combined with our understanding of how heat is lost from the human body during cold and windy days.

On windy days the speed of moisture evaporation from your skin increases and serves to move heat away from your body making it feel colder than it actually is. The exception to this rule, however, is when higher temperatures are concerned. At higher temperatures, wind chill is considered far less significant. Instead humidity plays a greater role. When a human being perspires, the water in his or her sweat evaporates. This results in the cooling of the body as heat is carried away from it. When humidity is high, the rate of evaporation and cooling is reduced, resulting in it feeling hotter than it actually is.

Using these facts we use a formula to adjust the air temperature based on our understanding of wind chill at lower temperatures, heat index at higher temperatures and a combination of the two in between.

You can get ‘feels like’ temperatures on our five day forecast and on our Android and iPhone apps.

Feels like temperatures on Met Office apps





Bitterly cold mornings continue for some this weekend

12 02 2012

Following a bitterly cold night across eastern England on Friday night, last night was not quite as cold. Friday night saw the lowest temperatures of the winter so far, falling to a biting -15.6C at Holbeach, Lincolnshire. On Saturday night the lowest minimum temperatures were across parts of southern and eastern England. The coldest locations, with values achieved early in the night before cloud amounts increased, were Cavendish: -12.7C Holbeach: -12.4C Cambridge: -12.2C Santon Downham: -11.9C Rothamstead: -11.7C.





Coldest temperatures of winter so far

11 02 2012

Last night and today have seen some of the lowest temperatures of the winter so far.

Official observations show Holbeach in Lincolnshire dropped to -15.6 °C overnight, beating the previous coldest temperature of this winter of -12.4 °C at South Newington in Oxfordshire overnight on 3-4 February.

Today has seen also the lowest day-time maximum temperature for the UK so far this winter, with Coningsby in Lincolnshire only getting up to -5.3 °C. The previous record for this winter was -2.8 °C, set at Cassley in Scotland on 15 January.

It’s worth noting that some even lower temperatures have been quoted in the media. However, these are not official Met Office observations.

Our official observation sites conform to rigorous standards set by the World Meteorological Organization (WMO). This includes observation equipment undergoing regular checks and calibration, as well as meeting requirements about the location of the observation site to ensure readings aren’t affected by other factors.

This doesn’t mean readings from non-official sites are wrong, just that they cannot be officially recognised because they are not part of our WMO-approved network.

The reason last night and today have seen these low temperatures comes down to a combination of factors. Cold air from the east is still flooding over parts of the UK. Snow is also still lying in some places, and this can keep temperatures down by acting like an ice pack – as well as reflecting back energy from the Sun. Clear skies and light winds have also played a part, as these factors mean heat can radiate away into the sky.

Looking ahead, tonight is expected to be cold, although it is unlikely to be quite as cold as last night. As we move through next week, temperatures are expected to move closer to or even slightly above average. You can stay up to date with the latest outlook with our forecasts and warnings.

 

Coldest overnight temperatures for 10-11 February

-15.6 °C Holbeach, Lincolnshire

-15.5 °C Cavendish, Suffolk

-15.3 °C Cambridge, Cambridgeshire

-15.2 °C Wainfleet, Lincolnshire

-14.6 °C Santon Downham, Suffolk





Freezing rain and snow across the country as the cold weather continues.

10 02 2012

Snow fell across a large part of England yesterday evening and last night. We saw between 1 and 8cm of fresh snow – the highest snowfall being from Lincolnshire through Cambridgeshire to Bedfordshire. The snow turned to rain in some western areas overnight, with ice becoming a hazard on untreated surfaces.

The table below shows the amount of fresh snow recorded the country overnight into Friday 10 February.

UK SNOW DEPTHS 10 FEB 0700

SITE NAME

SNOW DEPTH (cm)

AREA

CRANWELL

8

LINCOLNSHIRE

CONINGSBY

6

LINCOLNSHIRE

HEATHROW

5

GREATER LONDON

MIDDLE WALLOP

4

HAMPSHIRE

WITTERING

4

CAMBRIDGESHIRE

LECONFIELD

4

HUMBERSIDE

MARHAM

3

NORFOLK

BRIZE NORTON

3

OXFORDSHIRE

BENSON

3

OXFORDSHIRE

BOSCOMBE DOWN

3

WILTSHIRE

HIGH WYCOMBE, HQAIR

3

BUCKINGHAMSHIRE

ODIHAM

2

HAMPSHIRE

LARKHILL

2

WILTSHIRE

NORTHOLT

2

GREATER LONDON

FILTON

2

BRISTOL

WADDINGTON

2

LINCOLNSHIRE

HURN

2

DORSET

NOTTINGHAM, WATNALL

1

NOTTINGHAMSHIRE

BRIDLINGTON MRSC

1

HUMBERSIDE

DISHFORTH AIRFIELD

1

NORTH YORKSHIRE

The table below shows a list of the coldest spots across the country overnight into Friday 10 February.

UK MIN TEMPERATURES 10TH FEB 0900

SITE NAME

MIN TEMP (Celsius)

AREA

HOUGHTON HALL

-7.9

NORFOLK

SANTON DOWNHAM

-7.6

NORFOLK

HOLBEACH NO 2

-7.4

LINCOLNSHIRE

BROOMS BARN

-6.8

SUFFOLK

CONINGSBY

-5.5

LINCOLNSHIRE

CAVENDISH

-5.1

SUFFOLK

CHARLWOOD

-4.8

SURREY

MARHAM

-4.7

NORFOLK

CRANWELL

-3.8

LINCOLNSHIRE

VELINDRE

-3.5

POWYS

LINGWOOD, STRUMPSHAW HILL

-3.5

NORFOLK

WADDINGTON

-3.5

LINCOLNSHIRE

BEDFORD

-3.4

BEDFORDSHIRE

BUNTINGFORD

-3.4

HERTFORDSHIRE

WOBURN

-3.4

BEDFORDSHIRE

NORWICH AIRPORT

-3.3

NORFOLK

CHARSFIELD

-3.2

SUFFOLK

LECONFIELD

-3.1

HUMBERSIDE

ROTHAMSTED

-3.1

HERTFORDSHIRE

WYCH CROSS

-3.1

EAST SUSSEX

The cold weather is set to continue over the weekend with sharp frosts in many areas as temperatures fall to between -6 °C and -10 °C, with ice continuing to be a hazard to travellers in some areas. Saturday should be dry and bright in most areas, but cloudy and mild conditions across Scotland are expected to spread south for Sunday.





What’s bringing the cold weather to Europe and the UK?

9 02 2012

The current cold weather across Europe is in sharp contrast to the mild, wet and windy conditions across much of Europe through December and January. The cause of the cold conditions is the development of a large ‘blocking’ anticyclone over Scandinavia and north-western Russia. Easterly winds on the southern edge of this system has transported cold continental air westwards, displacing the more usual mild westerly influence from the Atlantic Ocean all the way to the British Isles.

Global land and sea surface temperature anomalies for 1-5 February 2012

Global land and sea surface temperature anomalies for 1-5 February 2012

A ‘blocking anticyclone’ can be thought of being like a very large boulder in a stream. This boulder acts like a dam, stopping the flow of the stream.  In this instance a block stops the more normal westerly flow that brings milder conditions, allowing colder conditions to win out from the east.

The origin and persistence of blocks has been a subject of much research, and unfortunately we are still not absolutely clear on why we see blocks form. What we do know though is that the origins of this large blocked pattern across Europe can be traced back to the appearance of two individual regions of mid-latitude blocking over central Russia and the Bering Sea in mid January. Over the next two weeks, these two regions merged together to form the ‘block’ we see now.

The appearance of significant blocking after a long absence is reflected in the strong decline of the Arctic Oscillation (AO) index, which effectively describes a state in the atmosphere where the flow of westerly winds is either stronger or weaker than usual in the northern hemisphere. It is currently in its negative phase, meaning the westerly flow is less strong than normal. The switch to a negative AO was seen in late January and highlights the dramatic change from generally strong westerly flow to the much less westerly or even easterly blocked state.   

Despite the general unpredictability of blocking patterns, there were potential signs of an increased risk of a significant cold weather several weeks ago when the high altitude winds began to weaken in longer-range forecasts. We now understand that there is a clear link between the weakening of these high altitude winds and the surface weather that operates on monthly timescales and in situations like this it can provide a ‘window of opportunity’ for monthly forecasts to warn of increased risk. Based on this understanding, the Met Office 16 to 30 day forecast has reflected the increasing risk of cold conditions since mid January.

Met Office Hadley Centre scientists have investigated and demonstrated a clear stratospheric influence on surface climate during these events, with easterly winds burrowing down through the atmosphere to affect the jet stream and surface climate. The result is a switch from mild westerly Atlantic flow over Europe to easterly winds with an increased risk of cold extremes.

Weakening of the jet stream in the Stratosphere can allow easterly winds to move down through the atmosphere to give cold easterly winds at the surface. This can result in cold and snowy weather across the UK.

A similar situation occurred at this time of year in 2009 when we had significant snowfall across the UK and other parts of Europe, following a strong breakdown of the high altitude jet. Although only some cold winter spells can be predicted in this way, other recent winters such as 2006 and 2010 have also shown clear examples of the effect.








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