Dreaming of a White Christmas?

17 12 2014
Summit of An Socach, the Cairngorms, Scotland.

Summit of An Socach, the Cairngorms, Scotland.

UPDATED FRIDAY 19th DECEMBER

With less than a week to go before Christmas Day, we are going to look at the likelihood of a white Christmas – will we be waking up to a picturesque covering of snow on the big day?

So far, December has seen some large fluctuations in the weather, with spells of wetter, milder conditions interspersed with colder, sunnier conditions with temperatures closer to average.

Through today and tomorrow, we will see plenty of fine weather across the UK, with some crisp winter sunshine. There will be some showers across the north and west of the country, that are likely to be wintry over higher ground.

A return to largely mild weather is expected from Sunday (21st), with cloudy, damp conditions for many parts, and there is the threat of some heavy rain in places.

As we head into Christmas Eve and Christmas Day, there is still a fair amount of uncertainty – which is as you’d expect this far ahead. The strongest signal currently shown in the computer models is for the colder, showery weather to return across Britain, with showers most frequent across the north and east. But will we see any snow?

At this point, the most likely areas that will see some of the white stuff will be across higher ground in the north, with rain at lower levels. Temperatures will be fairly close to average and there will be some frosty nights under clear skies.

It is important to note, however, that there’s still a small chance we could see different weather for Christmas Day. So with just under a week to go until the big day, it looks most likely that the majority of us won’t be seeing a white Christmas. Because of the uncertainty of long range forecasts, however, we recommend staying up-to-date with our website for the latest information on our forecasts and warnings.





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.





US snowfall and will it impact the UK?

20 11 2014

Parts of the US and Canada are seeing particularly cold weather and heavy snowfall at the moment.

Chart showing the position of the jet stream over North America as at 00:01 on 20 November.

Chart showing the position of the jet stream over North America as at 00:01 on 20 November.

A southward buckle in the jet stream has seen cold polar air flow south to north eastern parts of North America.

In the Buffalo region of New York state, temperatures have fallen as low as -15C and 4-5 ft (about 1.5 metres) of snow has fallen – enhanced by what’s known as the ‘lake effect’. Another 2-4 ft (about 1 metre) is expected through today.

The snowfall is set to ease on Friday with much milder conditions through the weekend giving a rapid and significant thaw – which could bring a risk of flooding.

This risk could increase through the start of next week when some very heavy rain is expected across the area.

What is lake effect snow?

Lake Superior (top left) and Michigan (centre) can be seen generating 'lake effect' snow. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

Lake Superior (top left) and Michigan (centre) can be seen generating ‘lake effect’ snow. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

This is an effect which applies to areas around large lakes like those seen in the northern US – Lake Superior has an area of more than 30,000 sq miles.

When cold air moves across the relatively warm waters of the lake, air rises due to convection which creates clouds and heavy showers. In cold conditions, the moisture in the clouds will fall as heavy snow.

As Buffalo as it the eastern tip of Lake Erie it has been particularly susceptible to this effect during the recent weather.

While we don’t have any lakes big enough for this effect in the UK, we can occasionally see a similar scenario when we get easterly winds in the winter.

Cold air from the continent can be warmed by the relatively warm North Sea as it moves across the water, bringing snow showers to eastern parts of the UK. However, there’s no sign of this in the immediate future for the UK.

Will the US weather affect the UK?

Many people believe that there’s a rule of thumb that weather in the US will arrive in the UK a few days later – but that’s by no means always the case.

In this instance, there’s high confidence that the cold snowy weather will stay on the western side of the Atlantic.

Also, in past winters similar weather situations in the US have strengthened the jet stream and increased the risk of storms across our shores. Again, in this instance, this isn’t expected at the moment.

What we do expect to see is further changeable weather over the coming few days.





Was it a white Christmas?

26 12 2013

Using technology such as radar, webcams and ground based sensors combined with the expert opinion of experienced forecasters, the Met Office is able to declare that no snow was reported by our Met Office Observers on Christmas Day 2013.

Although a few of our automated weather stations recorded sleet or snow over some hills, Christmas this year was green for most of Britain rather than white.





Cold snap expected

3 12 2013

The UK is going to see a very short, sharp, cold snap.  From Wednesday night (4th Dec) into Thursday morning (5th Dec) Scotland, northern England and Northern Ireland will see some strong winds, while Scotland will see some wintry showers and snow.  However temperatures will return to normal as we head through the weekend, and be more in line with what should be expected for December.

A rapidly deepening Atlantic depression is expected to move in an easterly direction to the north of Scotland bringing westerly gales, with gusts of 60 to 70 mph extending southwards across northern and some central parts of the UK on Wednesday night and Thursday.  Northern Scotland could see gusts of 80mph, and potentially 90mph for a time.

Because of this the Met Office has issued a Yellow Severe Weather Warning for strong winds. The public should be aware of possible disruption to travel, especially across Scotland, parts of Northern Ireland and Northern England.

The winds are expected to veer northerly and bring the colder arctic air southwards across northern areas before easing into Friday. The winds could exacerbate high tides and may increase the risk of coastal flooding in the Northern and Western Isles and along the East Coast of England.

A Yellow warning for snow is also in place. It runs from 6am Thursday to 12 noon on Friday, covering the northern half of Scotland, snow showers are expected to be most frequent across the Northern Isles, the North Highlands and northern Aberdeenshire.  Low laying areas could see 2 – 5cms of snow and higher altitudes 10 – 20cms. In addition the strong winds could lead to some drifting of snow and possibly blizzard conditions on higher ground.  Icy conditions may also develop on some roads across Scotland on Thursday night and Friday morning.

This winter storm is not expected to be as powerful as those in January 2012 and December 2011

This is expected to be a short-lived cold snap, with temperatures quickly recovering to near normal over the weekend.

Our video explains what to do during a Yellow warning for wind. You can also download a weather warnings widget for your website.





The Met Office’s outlook for UK winter

29 11 2013

There are some headlines in the media today which suggest the Met Office is warning of exceptionally cold weather for three months.

However, the Met Office hasn’t issued a warning along these lines and we have not highlighted months of ‘exceptionally cold’ weather ahead. If there is any sign of significantly cold weather or disruptive snow in the forecast, we will keep the country up to date through our forecasts and warnings.

The news stories are based on information taken from our three month outlook for contingency planners, so let’s take a closer look at that.

What does our three month outlook say?

This outlook is not like our other forecasts because, as we have discussed previously, it’s not currently scientifically possible to provide a detailed forecast over these long timescales.

Instead, the outlook assesses the level of risk connected to five different scenarios for both temperature and rain/snowfall. It’s a bit like the science-equivalent of factoring the odds on a horse race.

The current outlook for December-January-February says the chance of the coldest scenario happening is between 20 and 25% and the chances that the period will fall into the warmest scenario is between 10 and 15%.

So while uncertainty is quite large, below average temperatures are more likely than above average (for note, average maximum temperatures for the UK in winter are about 6.6C and average minimum temps are about 0.9C).

However, as with any horse race, it’s always possible that the favourite won’t win – so these probability scenarios have to be used in the right context. This is why they’re useful for contingency planners who plan ahead based on risk, but not that useful for the general public.

So what will winter be like?

Obviously there’s always a lot of interest to know what winter will be like – how cold will it be, how much snow will we get and where and when will it fall?

The Met Office is working with research partners around the world to improve longer range forecasting, but it’s not currently possible to forecast snow or exact temperatures three months ahead.

However, our 30-day outlook (under the text forecast tab) provides a look ahead to the general type of weather we’re likely to see in the UK.

Currently it says that after today, we’ll see settled weather and fairly normal temperatures into the first week of December before the chance of some colder, more changeable weather towards the end of next week. This may last a few days before giving way to milder and unsettled weather.

For the mid to latter part of December, there are indications that temperatures are likely to remain near or slightly below average for the time of year, but otherwise fairly normal conditions for early winter are most likely.

With regards to forecasting snow, because there are so many factors involved, generally that can only be discussed in any detail in our five day forecasts.

If there is any sign of significantly cold weather or disruptive snow in the forecast, we will keep the country up to date through our forecasts and warnings.





Winter Forecasting – Responding to the headlines

12 10 2013

Once again it is the season for speculation and big headlines regarding what the weather will do over the winter period. The front page of the Daily Express today claims: ‘Worst winter for decades: Record-breaking snow predicted for November’.

We saw similar headlines last year and instead winter 12/13 ended up being only the 43rd coldest on record with an average temperature of 3.3C and flooding until the turn of the year.

What the Daily Express has failed to explain to its readers is that there is absolutely no certainty about what weather the UK will see over the winter period. The science simply does not exist to make detailed, long-term forecasts for temperature and snowfall even for the end of November, let alone for the winter period, which does not officially start until 1 December.

While we have seen a return to more normal, cooler temperatures for this time of year, this is no indication of what we can expect over the next four months with regards to temperatures and when we might see snow. It is far too early to tell.

Ultimately, we’re heading into winter and it is perfectly possible that we will see the whole range of weather that we get in winter at some point over the coming months, including snow and freezing temperatures, but also heavy rain, windy weather and mild conditions too.

Our five day forecasts and warnings will provide you with the best possible guidance on any periods of cold weather, frost or the likelihood of snow, giving detailed local information across the UK to help you make the most of the weather over the coming months.





Met Office figures show we are on course for coldest March in over 50 years

28 03 2013

This March is set to be the coldest since 1962 in the UK in the national record dating back to 1910, according to provisional Met Office statistics.

From 1 to 26 March the UK mean temperature was 2.5 °C, which is three degrees below the long term average. This also makes it joint 4th coldest on record in the UK.

The table below gives details of statistics up to the 26 March for broken down by the counties used to compile climate statistics.

  mean temperature precipitation
  Actual  (deg C) Difference from 1981-2010 average (deg C) Actual (mm) Percentage of 1981-2010 average (%)
Regions        
UK 2.5 -3.0 62.2 65
England 2.9 -3.3 63.4 99
Wales 2.8 -3.0 86.2 74
Scotland 1.6 -2.5 50.3 36
N Ireland 3.0 -2.9 78.9 83
England & Wales 2.9 -3.3 66.6 94
England N 2.0 -3.5 54.0 72
England S 3.4 -3.2 68.4 118
Historic Counties        
Aberdeenshire 0.6 -3.1 67.9 86
Anglesey 3.9 -2.9 79.8 100
Antrim 2.9 -2.8 68.9 75
Argyllshire 2.5 -2.1 47.2 22
Armagh 3.1 -3.1 96.8 125
Ayrshire 2.0 -2.9 53.8 41
Banffshire 0.8 -3.1 56.4 76
Bedfordshire 3.0 -3.5 50.1 119
Berkshire 3.4 -3.2 78.5 157
Berwickshire 1.6 -3.2 65.0 108
Brecknockshire 1.9 -3.1 100.5 74
Buckinghamshire 3.1 -3.4 66.6 137
Buteshire 2.7 -2.3 58.0 36
Caithness 2.3 -1.9 45.5 52
Cambridgeshire 3.2 -3.5 40.0 102
Cardiganshire 2.8 -2.8 62.5 54
Carmarthenshire 3.4 -2.7 87.0 69
Carnarvonshire 2.8 -3.0 96.1 64
Cheshire 2.9 -3.5 42.1 72
Clackmannanshire 1.7 -2.7 65.3 57
Cornwall 5.1 -2.3 102.0 109
Cumberland 1.6 -3.3 42.1 37
Denbighshire 2.1 -3.4 66.2 75
Derbyshire 1.9 -3.7 58.8 81
Devon 4.0 -2.7 112.9 118
Dorset 4.0 -2.7 96.8 132
Down 3.2 -3.0 158.4 193
Dumfriesshire 1.3 -3.1 65.6 53
Dunbartonshire 2.1 -2.7 49.4 25
Durham 1.6 -3.4 61.9 99
East Lothianshire 1.9 -3.2 55.4 100
Essex 3.5 -3.3 44.2 110
Fermanagh 3.0 -3.0 45.6 42
Fifeshire 2.3 -3.0 58.8 89
Flintshire 2.9 -3.5 60.9 105
Forfarshire 0.9 -3.0 73.1 89
Glamorganshire 3.6 -2.8 123.1 98
Gloucestershire 3.2 -3.3 77.1 129
Hampshire 3.9 -2.9 85.4 133
Herefordshire 2.9 -3.5 80.3 134
Hertfordshire 3.2 -3.4 50.3 109
Huntingdonshire 3.1 -3.6 56.4 143
Inverness 1.3 -2.1 36.9 19
Kent 3.8 -3.1 58.2 121
Kincardineshire 1.5 -3.1 56.5 82
Kinross 1.5 -3.0 65.6 65
Kirkcudbrightshire 1.7 -3.0 79.2 54
Lanarkshire 1.2 -3.0 51.8 47
Lancashire 2.6 -3.3 41.1 45
Leicestershire 2.4 -3.8 52.4 114
Lincolnshire 2.7 -3.6 49.0 113
Londonderry 3.0 -2.8 59.3 60
Merionethshire 1.8 -3.1 98.6 62
Mid Lothianshire 1.7 -3.1 59.4 83
Middlesex 4.2 -3.3 57.7 128
Monmouthshire 3.1 -3.2 94.8 100
Montgomeryshire 2.0 -3.4 64.5 56
Moray 1.7 -2.8 39.5 60
Nairnshire 1.5 -2.9 32.0 47
Norfolk 3.0 -3.4 60.5 128
Northamptonshire 2.6 -3.6 61.0 133
Northumberland 1.5 -3.3 63.0 92
Nottinghamshire 2.6 -3.8 49.0 113
Oxfordshire 3.0 -3.3 74.3 149
Peeblesshire 0.4 -3.4 69.6 68
Pembrokeshire 4.0 -2.6 76.9 77
Perthshire 0.6 -2.6 58.8 39
Radnorshire 1.7 -3.2 87.8 91
Renfrewshire 2.5 -2.8 42.8 29
Ross and Cromarty 2.1 -2.0 35.1 20
Roxburghshire 1.0 -3.4 62.8 73
Rutland 2.4 -3.7 58.0 123
Selkirkshire 0.5 -3.1 76.5 68
Shropshire 2.6 -3.5 61.6 108
Somerset 3.8 -3.0 65.3 91
Staffordshire 2.3 -3.7 51.0 87
Stirlingshire 1.9 -2.9 53.2 36
Suffolk 3.2 -3.3 46.4 104
Surrey 3.7 -3.1 72.1 135
Sussex 4.0 -2.8 64.6 103
Sutherland 1.5 -2.4 38.8 27
Tyrone 2.8 -2.8 60.1 57
Warwickshire 2.8 -3.6 52.2 110
West Lothianshire 1.9 -3.1 49.3 62
West Suffolk 3.3 -3.5 31.8 80
Westmorland 1.2 -3.1 56.1 40
Wigtownshire 2.7 -2.8 55.5 51
Wiltshire 3.3 -3.0 76.1 118
Worcestershire 3.1 -3.5 63.9 133
Yorkshire 1.9 -3.6 59.0 84

Clearly March has been extremely cold and snowy and joins 2006, 2001, 1995, 1987, 1979, 1970 and 1962 as years when March saw some significant snowfall.

The cold weather is expected to continue through the Easter weekend and into April. You can stay up-to-date with forecasts and warnings online, through our mobile apps, facebook and twitter, and through TV and radio broadcasts.

The table below lists the coldest March average temperatures on record and details where March 2013 ranks in terms of cold months of March.

Area Coldest March

on Record

(deg C and year)

Rank of March 2013
Aberdeenshire -1.4 1947 5
Anglesey 3.6 1962 2
Antrim 2.2 1947 5
Argyllshire 1.5 1947 5
Armagh 2.9 1919/1947 4
Ayrshire 1.0 1947 5
Banffshire -1.0 1947 5
Bedfordshire 2.3 1962 2
Berkshire 2.6 1962 2
Berwickshire 0.3 1947 5
Brecknockshire 1.1 1962 2
Buckinghamshire 2.3 1962 2
Buteshire 1.5 1947 5
Caithness 0.0 1947 5
Cambridgeshire 2.6 1962 2
Cardiganshire 2.0 1962 3
Carmarthenshire 2.5 1962 3
Carnarvonshire 2.3 1962 3
Cheshire 2.6 1962 2
Clackmannanshire 0.1 1947 4
Cornwall 3.9 1962 2
Cumberland 1.0 1947 4
Denbighshire 1.4 1962 2
Derbyshire 1.5 1962 2
Devon 3.1 1962 2
Dorset 3.1 1962 2
Down 3.0 1937/1947 4
Dumfriesshire 0.5 1947 5
Dunbartonshire 0.3 1947 5
Durham 0.9 1947 4
East Lothianshire 0.2 1947 5
Essex 2.8 1962 2
Fermanagh 2.8 1947 3
Fifeshire 0.7 1947 5
Flintshire 2.4 1962 2
Forfarshire -0.6 1947 4
Glamorganshire 2.9 1962 3
Gloucestershire 2.6 1962 2
Hampshire 3.0 1962 2
Herefordshire 2.4 1962 2
Hertfordshire 2.4 1962 2
Huntingdonshire 2.6 1962 2
Inverness 0.0 1947 5
Kent 2.9 1962 2
Kincardineshire 0.3 1947 2
Kinross -0.1 1947 5
Kirkcudbrightshire 0.9 1947 3
Lanarkshire 0.0 1947 5
Lancashire 2.3 1962 2
Leicestershire 2.0 1962 2
Lincolnshire 2.4 1962 2
Londonderry 2.2 1947 5
Merionethshire 1.2 1962 3
Mid Lothianshire 0.1 1947 5
Middlesex 3.4 1962 2
Monmouthshire 2.5 1962 2
Montgomeryshire 1.3 1962 3
Moray -0.2 1947 5
Nairnshire 0.0 1947 5
Norfolk 2.5 1962 2
Northamptonshire 2.1 1962 2
Northumberland 0.4 1947 4
Nottinghamshire 2.4 1962 2
Oxfordshire 2.4 1962 2
Peeblesshire -1.2 1947 5
Pembrokeshire 3.2 1962 3
Perthshire -1.2 1947 5
Radnorshire 1.1 1962 2
Renfrewshire 0.8 1947 5
Ross and Cromarty 0.8 1947 5
Roxburghshire -0.4 1947 5
Rutland 1.9 1962 2
Selkirkshire -0.8 1947 5
Shropshire 2.1 1962 2
Somerset 3.0 1962 2
Staffordshire 1.9 1962 2
Stirlingshire 0.1 1947 5
Suffolk 2.5 1962 2
Surrey 2.8 1962 2
Sussex 2.9 1962 2
Sutherland 0.1 1947 5
Tyrone 2.3 1947 5
Warwickshire 2.3 1962 2
West Lothianshire 0.3 1947 5
West Suffolk 2.5 1962 2
Westmorland 0.4 1947 3
Wigtownshire 1.7 1947 3
Wiltshire 2.5 1962 2
Worcestershire 2.7 1962 2
Yorkshire 1.4 1947 3

The full month figures for March 2013 will be available later next week and a summary of the month will be issued soon after.





Latest snow depths and wind speeds – 24 March

24 03 2013

As forecast, we have seen some very wintry weather over the last few days. Here are some figures showing where the most snow has fallen.

Wittering in Cambridgeshire saw the deepest snow, with 24 cm recorded at 9 am this morning.

Many areas also saw strong winds, with a gust of 61 mph recorded at Shap, Cumbria and 48 mph recorded at Machrihanish, Argyll . These winds have caused even deeper drifts of snow in some areas.

Snow depths at 9 am 24 March

TIME SITE NAME AREA ELEVATION (m) SNOW DEPTH (cm)
09:00 WITTERING CAMBRIDGESHIRE 73 24
09:00 WATTISHAM SUFFOLK 89 20
09:00 NOTTINGHAM, WATNALL NOTTINGHAMSHIRE 117 19
09:00 SHAWBURY SHROPSHIRE 72 14
09:00 ANDREWSFIELD ESSEX 87 12
09:00 CRANWELL LINCOLNSHIRE 63 10
09:00 LEEK, THORNCLIFFE STAFFORDSHIRE 298 7
09:00 ABOYNE ABERDEENSHIRE 140 7
09:00 HIGH WYCOMBE BUCKINGHAMSHIRE 204 7
09:00 SENNYBRIDGE POWYS 307 7
09:00 SHAP CUMBRIA 252 7
09:00 COLESHILL WARWICKSHIRE 96 6
09:00 HAWARDEN AIRPORT CLYWD 11 6




March – a month of weather contrasts

18 03 2013

Winter seems to have hung on for quite some time this year with low temperatures, frost, ice and snow affecting many areas into late March. This isn’t altogether unusual as we are more likely to see snow at Easter than at Christmas. However, March 2012 was very different with plenty of sunshine and temperatures into the low 20s Celsius. How come?

Well, this time last year the UK was under the influence of high pressure. This gave us clear skies, plenty of sunshine and with a light southerly breeze, temperatures that were well above average. In fact, Scotland set an all time record maximum temperature with 22.8 °C at Fyvie Castle in Aberdeenshire.

Visible satellite image from March 2012

Visible satellite image from March 2012

This year, with a strong easterly wind bringing cold air from Scandinavia and Eastern Europe, we have quite the opposite with eastern parts of the UK in particular seeing snow, ice and temperatures around 20 degrees Celsius lower.

Visibile satellite image from March 2013

Visibile satellite image from March 2013

The direction of the wind therefore plays a major part in what type of weather you and I will see, especially as we have the Atlantic Ocean to our west and continental Europe to our south and east. Different wind directions bring air with different temperature and moisture contents. Meteorologically, they are termed air masses and in March 2012 we saw a Tropical Continental air mass bringing dry and warm air from the Mediterranean. This year we have been affected by a Polar Continental air mass, bringing cold air from the east. The following video explains exactly what we mean by air masses.

With different air masses constantly affecting the UK, the weather is a particularly challenging thing to forecast, especially so in March. This is because in early spring the sun is starting to rise higher in the sky and the amount of daylight hours start to increase. This means we get more heat building up in the lower part of our atmosphere. The result is slightly more energy, which in turn can lead to heavier showers. We can also see more unstable air and more active fronts as a result of greater heating. With more moisture available in the atmosphere, we also tend to see heavier or more prolonged rainfall and if this mixes with cold air, more snowfall. It makes forecasting more complicated because the extra heat and moisture adds another aspect to the weather, which tends amplify the effects of different air masses.

You can find out more about forecasting snow on our website or on the following video:








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