So what happened to our summer?

28 08 2015

Our Chief Scientist Professor Dame Julia Slingo OBE FRS reflects on this summer’s weather and what has influenced it:

No-one can deny that we have had a pretty disappointing summer with a lot of unsettled weather and only a few warm spells, especially through July and August. Our weather has been dominated by low pressure over and to the west of the country that has brought us periods of heavy rain from the south – what we call the Spanish Plume. So what has been happening?

If we look beyond our shores there have been some big changes in the global climate this year. El Niño is in full flight, disturbing weather patterns around the world. The low pressure that has dominated our weather is part of a pattern of waves in the jet stream around the world that has brought crippling heat waves to places like Poland and Japan. And, looking back over past El Niños, you could have expected that a more unsettled summer might be on the cards for the UK. Closer to home the North Atlantic is more than 2 degrees colder than normal. It seems quite likely that the unusually cold North Atlantic has strengthened and pushed our jet stream south, also contributing to the low pressure systems that have dominated our weather.

So could all this have been anticipated? Seasonal forecasts for this summer suggested that temperatures and rainfall would be near normal. However, as the season progressed all the leading models around the world failed to capture the signal for unsettled weather over the UK. We all know that forecasting months and seasons ahead is still in its infancy and much more research needs to be done. On the other hand our day-to-day forecasts have been really successful in allowing us to warn of bad weather, highlighting yet again the benefits of our research that has delivered year-on-year and decade-by-decade improvements in forecasting skill. Our 5-day forecast is now as accurate as our 1-day forecast was when I started my career. This enables us to make so many decisions that keep us safe, protect our property, keep our infrastructure running and even when to go out and enjoy the sunshine!

All of this cannot happen without improvements to research and technology, and this week the first phase of our new supercomputer went live, five weeks ahead of schedule. This will enable us to provide even more accurate and relevant weather and climate forecasts to all of us, our government, emergency responders, and our many other customers at home and abroad.

The news that the BBC has decided that the Met Office won’t be their main weather provider when the current contract ends has raised the question of where will the new provider get their information from. It’s important to understand that no weather forecasting organization, whether it is a National Met Service like the Met Office or an independent company, can provide a service without a forecast, and that it is the leading meteorological agencies, like the Met Office, that build and deliver those forecasts. So whoever the BBC chooses to deliver their weather services in future, you can be sure that Met Office observations and forecasts will continue to be at the heart of them. We are committed to driving forward the skill and usefulness of our forecasts and ensuring that all of us benefit from the advances the Met Office makes in the coming years with our new supercomputer.





First hurricane for Florida since Wilma ten years ago

26 08 2015

Tropical Storm Erika was around 390 nautical miles east of Antigua on Wednesday morning and is moving west at around 18mph. The storm is expected to track close to Puerto Rico and the Lesser Antilles  on Thursday and then towards the Bahamas or South Florida by the end of the weekend, by which time Erika will probably have developed into a Hurricane.

The official guidance from Miami is for Erika to gradually strengthen to a category 1 hurricane by the start of next week. Erika will be the second hurricane of the 2015 season. Hurricane Wilma, in October 2005, was the most intense hurricane recorded in the North Atlantic, with an estimated central pressure of 882 mb.

Image courtesy of National Oceanic and Atmospheric Administration

Image courtesy of National Oceanic and Atmospheric Administration

As well as potentially damaging winds, Erika is likely to produce very heavy rainfall and a modest storm surge.

When Erika passes over the Lesser Antilles on Thursday there is expected to be 120mm of rainfall in 24 hours, but as Erika deepens near to the Bahamas and South Florida, totals of up to 400mm in 24 hours could occur, although there is some uncertainty in the exact location and intensity of Erika at this stage.

It is 10 years since Hurricane Katrina made landfall in Florida. It was the most costly hurricane on record causing an estimated $108 billion in damage in Louisiana and Mississippi. It also caused an estimated 1500 deaths. The strongest winds  were recorded during 25-30 August 2005  and were over the coastal areas of Louisiana and Florida.

No major (cat 3 or above) hurricane has made landfall on the USA since Wilma in October 2005. As for cat 1/2 hurricanes over the USA, Arthur just made landfall in 2014 (glancing blow to N Carolina) and in 2012 Isaac made landfall over New Orleans.  Although technically not a hurricane, Sandy had hurricane force winds at landfall over New Jersey. Other US hurricane landfalls since 2005 have been Irene in 2011, Dolly, Gustav and Ike in 2008 and Humberto in 2007.





Highest temperatures and rainfall over the weekend

23 08 2015

Over the past 24 hours the weather has delivered a mixture of hot sunshine, thunderstorms, hail and heavy rain as we highlighted earlier in the week.

As expected, sunny skies and warm air being pushed northwards from the continent allowed temperatures to climb across central and eastern parts of the UK, reaching maximums in the high 20s and low 30s on Saturday with a humid feel:

Table showing Maximum temperatures for Saturday 22 August 2015

Location Maximum Temperature in C
Gravesend 30.9
Kew Gardens 30.9
Heathrow 30.7
St James’s Park 30.7
Northolt 30.6

These high temperatures set off two areas of thunderstorms, one over central southern England and another over the Midlands, moving into northern England. These storms caused localised surface water flooding and flooding of some properties in North Yorkshire as up to 30mm of rain fell in an hour. There were also impacts to the York-Leeds rail line.

Across the northwest of the UK it was fresher and mainly dry with some sunshine, while the areas in between were rather cloudy with some rain.

Overnight, the heavy, thundery downpours continued to move northwards, while heavy rain also spread into western parts of the UK. By this morning at 10am the rainfall totals for the 24 hours were as follows:

Table showing rainfall totals for the 24 hours up until 10am on Sunday 23 August 2015

Location Rainfall in mm
Bramham 62.6
Ryhill 54.6
Tredegar 40.6
Linton-on-Ouse 39.8
Scolton Country Park 36.8

During today, the heavy rain has continued to spread north and eastwards with a mixture of sunny spells and heavy showers following across the south. Ahead of this, temperatures across eastern England have again peaked in the mid to high 20s.

Table showing rainfall totals bwtween 10am and 4pm on Sunday 23 August 2015

Location Rainfall in mm
Hereford 20.8
Llanbrynmair 20.4
Sarn 17.8
Lake Vyrnwy 17.2
Porthmadog 17.2

The changeable weather will continue as we head into next week. Met Office National Severe Weather Warnings have been issued and everyone is encouraged to keep up to date with forecasts and warnings over the next few days and to make plans accordingly.





Rain or shine this weekend?

20 08 2015

You may have heard that this weekend could be cloudy and wet…or sunny and dry, that’s because as with other weekends this summer there has been some uncertainty in the forecast.

After a mixed week of some sunshine, rain and showers it looks like we’ll see more of the same over the weekend as a frontal system interacts with warm, humid air spreading northwards from the continent.

We are now fairly confident that on Saturday the UK will be split weather wise. There’ll be bright and breezy weather in the north west with a few showers. Meanwhile the south east will be warm and humid, perhaps hot with temperatures in the high 20s which could set off a few isolated thunderstorms. In between we expect to see a band of cloud and rain which could be heavy and persistent at times.

Overnight and into Sunday the wet weather is expected to become more widespread across England and Wales and move into Scotland with some heavy rain at times.

Sun23Aug12z

At the moment, central and western parts of the UK seem most likely to see the heaviest, most persistent rainfall as the frontal system pivots. However, this pivot position could change over the coming days, and this is critical because it will determine whether we need to issue weather warnings.

Once we have more certainty where the most persistent, heavy rain will be we will review whether a Met Office National Severe Weather Warning is required. Therefore, as ever, it is best to check the latest forecast if you have plans for the weekend.

Tony Berry, Visitor Experience Director at the National Trust said: “Despite the unsettled weather this weekend, there’s still loads to do at National Trust places across the country. From windswept coastal paths and woodlands to hundreds of historic houses and gardens, there’s always something to explore come rain or shine. We’ve got a whole host of activities to wear the kids out too, with everything from pirate adventures and fossil hunts (just remember to pack the waterproofs and wellies) to storytelling and wild art. And throughout August we’ll be bringing the coast to a whole host of cities across the UK in the form of a giant shell – Shellsphere – where passers-by will have the opportunity to see, smell, hear and taste the sea.”

Next week, we’ll continue to see a combination of drier, sunny days with cloudier spells and some rain or showers at times but it will be warmer than recently.





Summer downpours on the way

11 08 2015

The weather forecast for later this week is presenting a challenge for our meteorologists.

All the ingredients are present to produce significant rainfall on Thursday and Friday, but complex interactions in the atmosphere make it difficult to say with certainty where the rain will be most intense.

An area of low pressure is expected to develop and push north across the Bay of Biscay and western France on Wednesday night and into Thursday, arriving across southern England on Thursday morning. As it comes north, very warm air over the continent is expected to be drawn into the low pressure’s circulation, making it feel very humid across central and southern areas of the UK

Fri1400z

Forecast pressure chart valid for 1am on Friday showing the location of the low pressure system over the southeast of the UK.

Warmer air can carry more moisture, and as such some very heavy rain is possible. However, this type of situation is difficult to forecast accurately a few days ahead and there is some uncertainty about which areas will see the heaviest rainfall. Current indications are that central and southern England and Wales are most likely to be affected. We may also have hail and thunder, this is most likely early on Thursday and then again Friday afternoon.

As we have already seen this summer, this type of weather situation has the potential to cause sudden, localised surface water flooding and hazardous travelling conditions.

Met Office National Severe Weather Warnings have been issued and these will be updated over the next few days as confidence in where and when we will see the heaviest rainfall increases.

Looking further ahead, the whole system is expected to clear away to the east during Saturday, with drier, fresher weather following to all parts with some sunshine.





Taiwan preparing for violent Typhoon

4 08 2015

A Typhoon is expected to bring flooding to parts of Taiwan and eastern China later this week with 500-700mm of rain forecast. Typhoon Soudelor is at the moment moving through the northwestern Pacific Ocean and looks likely to track across central Taiwan on Friday before making landfall over eastern China as it weakens.

This is a violent typhoon and is presently 500 miles to the west of the Northern Mariana Islands in the northwestern Pacific Ocean and is moving towards Taiwan. Currently surface wind speeds are estimated to be 130 mph with gusts of 190 mph, although these speeds are likely to ease slightly before reaching Taiwan.

Picture courtesy of Japanese Meteorological Agency

Picture courtesy of Japanese Meteorological Agency

This storm brings the threat of a storm surge and high waves to coastal areas of Taiwan and the southern Ryukyu Islands by Friday, as well as very strong winds quite widely, including to the capital of Taiwan, Taipei. Torrential rain is also expected which will bring a risk of significant flooding with the potential for 500-700mm rain falling in some areas in a 24 hour period.

The exact track of the storm could change over the coming days; you can see the latest track of Typhoon Soudelor through Storm Tracker and by following @metofficestorms on Twitter.





A wet getaway

24 07 2015

As many of us plan to head off on holiday, heavy rain and strengthening winds cross southern England today (Friday), persisting overnight in the east, before clearing on Saturday morning.

A Yellow warning has been issued for southeast England and East Anglia, valid from Friday afternoon to 11am Saturday because of the potential impacts the heavy rain and wind could have.

 

Weather warning 24.07.15

As an area of low pressure is crossing northeastwards across the UK today (Friday), close to southern England, it deepens into quite an intense feature for this time of year and is expected to bring disruptive rain and wind, particularly within the warning area.

More than 30 mm of rain is expected quite widely, but there is a chance some isolated locations could well see more than 70 mm of rain. Wind gusts are also expected to be strong across the warning area, with northerly winds gusting to 45 mph inland and around 55 mph along coasts. This combination of factors could bring the risk of disruption to outdoor activities and heavy holiday traffic.
Highways England has launched a website especially for drivers heading to the South West of England to help plan their journey.





A summer forecasting challenge for Friday

22 07 2015

Forecasting rainfall for the UK during the summer has always posed a more difficult challenge than other times of year – and the weather for this Friday is a perfect example.

The various computer models the Met Office uses to forecast the weather differ on how a low pressure system forming to the west of the UK will behave.

We know that it will bring some wind and rain to the southern half of the UK, but there is no consensus on exactly which track it will take across the country and precisely when it will arrive.

Below you can see the area most likely to see some persistent rain during Friday and into Saturday. There is a 30% chance that rainfall could extend further north than this. The system is likely to bring up to 15-25 mm of rain and winds of up to 30 mph, mainly in exposed areas.

Forecast uncertainties 24-25-July

Currently there are no plans to issue a weather warning for this event, but clearly it has the potential to affect people’s plans for Friday now summer holidays are in full swing.  You can hear more about Friday’s forecast in the video below.

We’ll be keeping a close eye on the situation as it develops to ensure everyone has the clearest picture of what’s likely for Friday, so it’s worth staying up to date with the forecast over the next couple of days.

The current situation is a good example of why summer is tricky because at this time of year the details are vitally important.

Will the showers be inland or at the coast, when will low cloud clear to let warm sunshine through? In winter this might not be so important, but in summer when many are outside making the most of all the UK has to offer it can make a huge difference to your day.

Familiar features of our landscape such as hills, valleys or the sea can cause subtle variations in heat and moisture and therefore dominate the local weather outcome.  This can result in big differences in the weather in quite small areas, it can be sunny on the beach but raining inland or a village fair could be rained off while the next village down the road is dry.

At this time of year it’s always a good idea to keep a close eye on the forecast as the situation can change from day to day.

We’re always harnessing new science and technology to make forecasting ever more accurate and summer forecasting is a major focus for future gains.





Summer returns but no heatwave

2 06 2015

There have been some stories in the press that a heatwave is on the way later this week.  Although we are expecting temperatures to rise over the coming days with some pleasant early summer weather, any very warm weather will be fairly short-lived.

After an unseasonably cold, wet and windy start to June and the meteorological summer, high pressure is expected to build across southern parts of the UK from Wednesday, resulting in a much quieter and more pleasant spell of weather.

By Friday, a plume of hot air from the continent could bring temperatures in the mid 20s°C  across south eastern parts of the country, but this in turn is likely to trigger some thundery showers. So although temperatures are likely to peak on Friday, this may not necessarily be accompanied by blue skies and sunshine, as a good deal of cloud is possible along with rather humid and hazy conditions.

Deputy Chief Meteorologist Martin Young said “although things will be a good deal warmer than of late, there still remains considerable uncertainty about how hot it will be and exactly where will see the highest temperatures on Friday, and the public should keep in touch with the latest forecasts”.

This coming weekend is likely to see temperatures a little lower than Friday’s in the south east, but plenty of pleasantly warm sunshine is expected across much of the UK with temperatures widely in the high teens, and reaching the low 20s°C  in parts of the south.





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.








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