How will activity in the Atlantic affect UK weather?

15 10 2014

There’s lots of activity going on in the Atlantic at the moment – but how will it affect the UK?

Currently there is a big area of low pressure covering a large part of the Atlantic between North America and the UK.

While it is fairly large in its size, it’s not particularly intense, powerful or unusual.

Forecast chart for 1pm on Wednesday 15 October 2014, showing large area of low pressure in the Atlantic.

Forecast chart for 1pm BST on Wednesday 15 October 2014, showing a large area of low pressure in the Atlantic.

This means that – while it may look impressive on the charts – it’s not going to bring anything out of the ordinary for the UK over the next few days.

It will, however, be generally unsettled across many parts through Friday and the weekend, as the low pressure drives a weather system across the UK.

This will bring strong winds, with gusts of up to 50mph in the most exposed parts of the west, and rain in places. However, some parts will enjoy periods of drier and brighter weather.

Tied up in the general Atlantic circulation is an area of warm air which was originally part of tropical storm Fay.

This will bring very mild air across parts of the country, with daytime temperatures possibly reaching around 20C across southeastern areas by Saturday, well above the October average for the region of 15C.

While it will be very mild, it may not feel particularly warm given the windy and often wet conditions. The unsettled weather is expected to be fairly standard for the middle part of October.

Forecast track of Gonzalo from the US National Hurricane Center.

Over the other side of the Atlantic near Bermuda, Hurricane Gonzalo is currently expected to track north and then east across the ocean over the coming days.

There is large uncertainty about the potential track of this storm, with some models suggesting that the remnants could move across the UK whilst others show them staying away from our shores.

If the ex-tropical storm does move across the country, some parts could see gales and heavy rain, but currently extreme conditions look unlikely.

As ever, we’ll keep a close eye on developments over the next few days and keep everyone up to date if it looks like there is any sign of severe weather heading for the UK.





Japan and India Braced for Tropical Cyclones

9 10 2014

Last weekend Typhoon Phanfone brought strong winds and heavy rain to many parts of Japan causing damage and disruption to travel. Japan is now preparing for another typhoon which could be just as disruptive, if not more so.

Typhoon Vongfong has been gathering strength and moving slowly across the western Pacific all week and has become the strongest tropical cyclone to have occurred anywhere in the world since the devastating Typhoon Haiyan which struck the Philippines last November. At its peak Vongfong was estimated to have sustained winds near 180 mph and a central pressure of 900 mb.

Forecasts for Typhoon Vongfong have been very consistent and predict that it will firstly cross some of the Ryukyu Islands of Japan at the weekend. The typhoon will then turn north-eastwards and cross Japan’s main islands at the beginning of next week starting with Kyushu in the south-west. At that time Vongfong is likely to be weaker than at present, but still expected to be a typhoon bringing strong winds and heavy rain and likely to cause disruption.

Typhoon Vongfong seen on 8 October 2014

Typhoon Vongfong seen on 8 October 2014

 

 

 

 

 

 

 

 

 

 

Meanwhile, in the Bay of Bengal Tropical Storm Hudhud has formed and threatens India at the weekend. Exactly a year ago intense Cyclone Phailin formed in a similar location and took a similar track that Tropical Storm Hudhud is expected to take. Hudhud (an Omani name for a type of bird) is expected to make landfall on the Indian coast early on Sunday and bring stormy conditions to both Andhra Pradesh and Odisha states. By that time it is expected to have developed into a fully blown ‘cyclone’ – equivalent to a typhoon or hurricane.

Tropical Storm Hudhud seen on 9 October 2014 Image courtesy of the India Meteorological Department

Tropical Storm Hudhud seen on 9 October 2014
Image courtesy of the India Meteorological Department

 

Official warnings of west Pacific tropical storms are produced by the Japan Meteological Agency and north Indian Ocean warnings are produced by the India Meteorological Department. The Met Office routinely supplies predictions of cyclone tracks from its global forecast model to regional meteorological centres worldwide, which are used along with guidance from other models in the production of forecasts and guidance.

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.





How will ex-Hurricane Cristobal affect the UK’s weather next week?

27 08 2014

The third tropical storm in the North Atlantic, Cristobal, has been making some headlines about its potential positive impact on us here in the UK – so what’s actually happening?

Cristobal is currently categorised as a hurricane and is currently between Bermuda and northeast Florida in the western Atlantic.

The storm is forecast to move north-east across the Atlantic over the coming days, changing to an ex-hurricane as it moves away from the warmer waters where it formed.

However, unlike ex-Hurricane Bertha which moved straight to the UK and brought strong winds and heavy rain to much of the British Isles, ex-Hurricane Cristobal is set on a very different track.

Instead it is forecast to move towards Iceland, staying well away from the UK as you can see from the forecast pressure chart below.

Forecast pressure chart for 1pm on Sunday 31 August shows ex-Cristobal heading towards Iceland.

Forecast pressure chart for 1pm on Sunday 31 August shows ex-Cristobal heading towards Iceland.

As Cristobal tracks to the north-west of the UK it could bring stronger winds across northwestern parts of Scotland for a time and there will also be some rain moving across the UK on Sunday into Monday.

It will have a longer lasting and more positive impact on our weather, however, as the track of the storm will result in an area of high pressure building further to the south and over the UK.

This high pressure will be maintained through next week as the jet stream moves to the north of the UK, bringing settled conditions across the country.

At this time of the year, high pressure generally brings dry and fine weather with some spells of sunshine, and that’s what we expect to see from around Tuesday next week.

With high pressure, daytime temperatures could reach the low to mid 20’s Celsius in places. This warmth will be especially noticeable following the cool conditions of late.

This spell of warm weather, however, doesn’t fit the definition of an Indian Summer – which you can read about on our website.





Ex Bertha more likely to miss UK

6 08 2014

7 August update: The latest update about the whether ex-Bertha will affect the UK can be found in our news release

 

Tropical Storm Bertha is currently off the north east coast of the US and is likely to become an ‘extra tropical storm’ on Thursday.

It’s then expected to track across the Atlantic – and while there are still a number of possible outcomes, it looks increasingly likely that the UK will miss any serious impacts from ‘ex Bertha’.

The Met Office has been assessing the likelihood of the UK seeing any effects from Bertha by using our own forecast model alongside models from other world-leading forecast centres.

Map shows likely storm track for ex Bertha by midday Sunday.

Map shows likely storm track for ex Bertha by midday Sunday.

At the moment the majority of forecasts from those models suggest ex Bertha will track to the south of the UK as a relatively weak low pressure system.

In fact it’s debatable whether this is even ex Bertha, as the storm declines to such an extent as it comes across the Atlantic that it fragments.

Some of the warm air which it drags across then leads to a new weak low which generates an area of heavy rain. This could move across northern France and possibly clip eastern parts of the UK on Sunday.

A much smaller number of model outcomes suggest ex Bertha will move across the UK as a more distinct feature which could bring some strong winds and heavy rain. Because these outcomes are in a minority, however, they are less likely.

While there remains a good deal of uncertainty about the weather on Sunday, it currently looks as if it will be fairly unsettled with some rain and breezy conditions – but nothing too unusual for the time of year.

It’s worth noting that it’s likely that the south east of England will see some heavy rain on Friday, which is not part of Bertha. You can see more about this on the Met Office’s severe weather warnings page.

We’ll be keeping an eye on the latest outlook for the weather over the next few days and the progress of ex Bertha to keep everyone up to date with the latest information.





Is Tropical Storm Bertha heading for the UK?

4 08 2014

Update: The latest update about the whether ex-Bertha will affect the UK can be found in our news release

A Tropical Storm called Bertha, which is currently in situated off the east coast of the US, could head towards Europe over the next week – so what’s the outlook?

Forecast tracks for Bertha, which was a hurricane but has now been downgraded to a tropical storm, suggest it will head north – staying offshore from the eastern coast of the US before turning to track east across the Atlantic.

Forecast track for Bertha from StormTracker shows it heading north off the east coast of the US before turning east.

Forecast track for Bertha from StormTracker shows it heading north off the east coast of the US before turning east.

While all forecast models suggest the storm will head in the general direction of UK and continental Europe, there remains a lot of uncertainty about exactly what it will do.

One certainty is that as the storm heads north away from the very warm seas which drive its power, it will lose strength and become what’s known as an extra-tropical storm – so we won’t be seeing a ‘hurricane in Europe’, but there is a chance we could see a fairly active summer storm.

The development of hurricanes and extra tropical storms can present complexities for meteorologists, and Bertha is a good example of that.

Here at the Met Office we use several world-leading forecast models as well as our own, and this gives an indication of how certain a forecast is. If all the models agree, there’s higher certainty, if they diverge, we know the atmosphere is finely balanced and there are several possible outcomes.

Satellite image of Bertha in the Caribbean taken at 11.45am on Monday, 4 August 2014 (Picture from NOAA)

Satellite image of Bertha in the Caribbean taken at 11.45am on Monday, 4 August 2014 (Picture from NOAA)

In the case of Bertha each of the models we use gives a very different picture of what the storm will do. This ranges from Bertha heading towards France as a weak feature which will completely miss the UK, to it arriving as a fairly active summer storm.

In terms of timing, there’s also a spread of possibilities – but it looks likely that the earliest Bertha would affect the UK would be on Sunday or into the start of next week.

As time progresses, different models normally come more in to line with each other and uncertainty decreases. The Met Office will be keeping an eye on how this situation develops over the next few days to give everyone in the UK the best advice on what Bertha is likely to do.

Given the time of year and the potential heavy rain, strong winds and large waves Bertha could bring if it does head to the UK, we’d advise everyone to stay up to date with the latest forecasts and warnings from the Met Office over the next few days.

You can also see the forecast track for Bertha and other tropical storms on our StormTracker pages.

NOTE – story updated to reflect Bertha’s status after being downgraded to a tropical storm.





Met Office predicts below average Atlantic hurricane season

22 05 2014

The Met Office Atlantic tropical storm forecast for 2014 is for 10 tropical storms between June and November, with a 70% chance that the number will be in the range 7 to 13. The long-term average over the period 1980–2010 is 12 tropical storms.

Specifically for hurricanes (storms with winds of at least 74 mph) the best estimate is 6, with a 70% chance that the number will be in the range 3 to 9; the 1980–2010 average is 6 hurricanes.

The most likely value for the Accumulated Cyclone Energy (ACE) index — a measure of the strength and duration of storms over the season — is 84, with a 70% chance that the index will be in the range 47 to 121; the 1980–2010 average ACE index is 104.

An image of Hurricane Sandy taken on October 28, 2012.  CREDIT: NOAA/NASA GOES Project.

An image of Hurricane Sandy taken on October 28, 2012. CREDIT: NOAA/NASA GOES Project.

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

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 whereas La Niña conditions can enhance tropical storm activity, so how these conditions develop will be important for the storm season ahead.”

Current evidence from observations and forecast models indicates a 70% chance of an El Niño event developing this year, with thresholds likely to be reached by the peak of the hurricane season. This is no guarantee, however, that El Niño conditions will occur.

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

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

The forecast also uses information from the seasonal prediction system of the European Centre for Medium-Range Weather Forecasts (ECMWF).

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





Humberto is the first hurricane in a quiet season so far

11 09 2013

The Atlantic hurricane season is usually reaching its peak during the first half of September, but so far the season has been very quiet.

Humberto has just become the first hurricane of the Atlantic season. In the last 70 years only one season has seen the first hurricane form later.

humberto_20130911_1000z

There are various ways of measuring tropical storm activity including the number of storms, the number of hurricanes and something called the Accumulated Cyclone Energy (ACE) Index. The latter measure takes into account both the strength and duration of storms and so gives a good indication of how active a season it has been. Whilst there have been eight tropical storms in the Atlantic so far, many have been weak and short-lived and thus the ACE Index is only running at 27% of where it would be in an average season at this time in the year.

It is not only the Atlantic which is seeing low levels of tropical storm activity. ACE Index across the whole northern hemisphere is running at 42% of average for this point in the season. There have only been two major typhoons in the west Pacific, which is an unusually low number.

It is worth noting that a quiet start to the Atlantic season does not necessarily mean the season will remain quiet. For example, in 2001 there had only been five tropical storms to this point in the season with just one becoming a hurricane. However, the remainder of the season saw another 10 tropical storms of which eight became hurricanes.

Official forecasts of current Atlantic tropical storms are provided by the National Hurricane Center. Visit our tropical cyclone pages for more information or follow @metofficestorms on Twitter.





Met Office predicts above average Atlantic hurricane season

20 05 2013

The Met Office Atlantic tropical storm forecast for 2013 is for 14 tropical storms between June and November, with a 70% chance that the number will be in the range 10 to 18.

The long-term average over the period 1980–2010 is 12 tropical storms. The last three hurricane seasons have all recorded above average tropical storm activity.

The most likely Accumulated Cyclone Energy (ACE) index — a measure of the strength and duration of storms over the season — is 130, with a 70% chance that the index will be in the range 76 to 184; the 1980–2010 average ACE index is 104.

For the first time this year, the Met Office are also releasing a forecast of the number of hurricanes (storms with winds of at least 74 mph), following the success of experimental forecasts produced throughout the 2012 hurricane season.

Between June and November 2013 the best estimate is for 9 hurricanes, with a 70% chance that the number will be in the range 4 to 14; the 1980–2010 average is 6 hurricanes.

Overall, these indicators point to a preference for above-average activity this year.

The evolution of the El Niño/La Niña cycle over the next few months is likely to play a large part in the North Atlantic hurricane season.

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 whereas La Niña conditions can enhance tropical storm activity, so how these conditions develop will be important for the storm season ahead.”

The tropical storm forecast is produced using the Met Office’s new seasonal prediction system GloSea5. The model has higher resolution than its predecessor, with better representation of the complex physical processes that cause tropical storms and hurricanes. The forecast also uses information from the seasonal prediction system of the European Centre for Medium-Range Weather Forecasts (ECMWF).

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





A challenging forecast for the weekend

20 09 2012

This weekend’s weather forecast is proving more challenging than usual as we see signs of much more unsettled conditions developing for all parts of the UK over the next few days.

Much of the UK is set to have a fine and dry weekend with sunny spells, light winds and temperatures in the mid to high teens Celsius after some cold nights.

There is now increasing confidence that southern parts of the UK (roughly south of a line from south Wales to Ipswich) will see wet and windy weather on Sunday.

This wet and windy weather is not the remnants of tropical storm Nadine – this stays close to the Azores. However, we are expecting a new area of low pressure to develop to the west of Iberia on Saturday which will move northeast, pulling some warm air from Nadine with it. It is this that would bring wet and windy weather to the far south of England and Wales for Sunday and other parts of the UK next week.

The challenge for forecasters is to pinpoint how this low pressure area will move. The weather forecast models available to Met Office forecasters are giving slightly different answers to this problem. As Anthony Astbury, Met Office Deputy Chief Forecaster, explains: “One model brings the low over Brittany giving rain and gales in the south of England, while another brings the low further west, with the risk of wet and windy weather for southwestern England and south Wales.”

There is still uncertainty about how the low pressure area will develop and move on Monday, and therefore which areas of the UK will see the worst of the weather early next week.

However, this heralds a spell of very unsettled weather for the whole of the UK for next week, with all parts seeing unsettled and windy conditions with showers or longer spells of rain.

Keep up to date with the forecast and warnings for the latest information.





Tropical Storm Isaac heads toward New Orleans

28 08 2012

At 1500 UK time on Tuesday 28 August, Tropical Storm Isaac was located about 150 km southeast of the Louisiana coast and heading northwest at about 15 km per hour.  Mean wind speeds of 70 mph at the surface  have been observed by the United States National Hurricane Center aircraft. These mean wind speeds maintain Isaac as a tropical storm, just below hurricane strength which requires mean wind speeds of over 74 mph.

Satellite image showing Tropical Storm Isaac

Satellite image showing Tropical Storm Isaac (Source: NOAA)

Although Isaac is expected to make landfall within the next 12 to 18 hours, there is still time for Isaac to intensify and become a hurricane. The official United States National Hurricane Center (NHC) forecast track predicts an intensification of this system into a category 1 hurricane as it continues its track northwestwards over the very warm Gulf of Mexico with winds increasing to around 80 mph when Isaac makes landfall at around 0600 UK time on Wednesday morning. 

Official National Hurricane Centre Forecast for Isaac on Tuesday 28th August

Official National Hurricane Centre Forecast for Isaac on Tuesday 28th August

The latest forecast from the NHC suggests that Isaac will pass just to the west of New Orleans, though there is still some uncertainty over the exact track and intensity of the storm and the impact of Isaac will be felt quite widely along the Gulf coast region.

Although hurricane Isaac is not expected to be as intense as hurricane Katrina which caused massive damage to New Orleans 7 years ago, there is still a risk of extreme rainfall with up to 500 mm in 48 hours resulting in flash flooding and storm surge along the coast, in addition to the damaging winds.  As Isaac moves inland it will weaken, but is still likely to result in torrential rain, perhaps with tornados or very squally winds.  There is a risk of flooding over the lower Mississippi valley region for the next few days.

You can find out more about Tropical Cyclones on our website or read our case study on Hurricane Katrina on the Met Office Education website. 








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