Cyclone Quartet Straddle the Pacific Ocean

8 08 2014

In the last few days a quartet of tropical cyclones have been active across the Pacific Ocean. For a period of time all four were simultaneously of hurricane intensity (winds greater than 74 mph). This is the first time this has happened in the Pacific Ocean for 12 years. Here we take a look at each of the storms and their likely impact.

Typhoons Halong and Genevieve and Hurricanes Iselle and Julio seen on 7 August 2014 Original images courtesy of University of Wisconsin

Typhoons Halong and Genevieve and Hurricanes Iselle and Julio seen on 7 August 2014
Original images courtesy of University of Wisconsin

Typhoon Halong formed near the US island of Guam and has been active in the west Pacific for over 10 days. It is now heading north towards south-western Japan and is set to bring strong winds and heavy rain this weekend to the area only recently affected by Typhoon Neoguri.

Typhoon Genevieve originated in the east Pacific and for a long time was a weak storm, even weakening to a remnant low pressure area at one stage. However, in the central Pacific Genevieve rapidly strengthened as it traversed an area of warm waters and gained hurricane status. As it crossed the International Dateline Hurricane Genevieve became Typhoon Genevieve. There is no difference between hurricanes and typhoons except that the former is used to describe tropical cyclones east of the Dateline and the latter to the west of the Dateline. Genevieve looks set to end its life as a tropical cyclone in mid-ocean well away from land.

Hurricane Genevieve as it crossed the International dateline and became a typhoon on 7 August 2014.  Image courtesy of US Naval Research Laboratory.

Hurricane Genevieve as it crossed the International dateline and became a typhoon on 7 August 2014.
Image courtesy of US Naval Research Laboratory.

Hurricane Iselle formed in the east Pacific just over a week ago. Iselle was downgraded to a tropical storm just as it made landfall over Hawaii today, but is still bringing strong winds, surf and heavy rain. Tropical storm or hurricane strikes directly over Hawaii are very rare. The last hurricane to make landfall over Hawaii was Iniki in 1992.

Rainfall radar showing Tropical Storm Iselle approaching Hawaii 8 August 2014. Image courtesy of NOAA

Rainfall radar showing Tropical Storm Iselle approaching Hawaii 8 August 2014.
Image courtesy of NOAA

Hurricane Julio is following hard on the heels of Hurricane Iselle in the east Pacific and has become a ‘major hurricane’ with winds in excess of 115 mph.

 

Julio is also heading in the direction of Hawaii, but looks likely to track a little further north than Hurricane Iselle. However, the US state could still feel the affects of Julio as it passes by on Sunday.

Official warnings of west Pacific tropical storms are produced by the Japanese Meteorological Agency . Central Pacific warnings are issued by the Central Pacific Hurricane Center and east Pacific warnings by the US National Hurricane Center. 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.





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.





Arthur becomes first Atlantic hurricane of the season

3 07 2014

Hurricane Arthur has become the first hurricane of this year’s Atlantic season, which started at the beginning of June.

Arthur is currently located close to the coast of south-eastern USA and is expected to move north-east, parallel to the coast, in the next few days.

Although the centre of the hurricane may only graze the coast it is likely to produce a storm surge several feet above normal tide levels and cause strong surf and rip currents along stretches of the US east coast.

Hurricane warnings have been issued by the National Hurricane Center for the North Carolina coast.

Hurricane Arthur - Image from NASA’s Aqua satellite courtesy of Colorado State University

Hurricane Arthur – Image from NASA’s Aqua satellite courtesy of Colorado State University

Seasonal forecasts for the Atlantic mostly indicate that there is likely to be a slightly below normal level of activity this season.

The Met Office forecast is for the most likely number of tropical storms in the season to be 10 with six of these likely to become hurricanes.

Further details can be found in our North Atlantic tropical storm seasonal forecast web page.

Meanwhile in the west Pacific a tropical depression has formed just south of the island of Guam.

This is expected to strengthen into a powerful typhoon over the weekend and could potentially threaten parts of Japan or Korea by the middle of next week.

Official forecasts of Atlantic and east Pacific tropical storms are provided by the National Hurricane Center.

Official warnings of west Pacific tropical storms are produced by the Japanese Meteological Agency (JMA).

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.





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.





Typhoon Haiyan heading for the Philippines

6 11 2013

Typhoon Haiyan is set to make landfall over the central Philippines on Friday bringing extremely strong winds and heavy rain to the region.

Typhoon Haiyan approaching the Philippines 6 November 2013

Typhoon Haiyan approaching the Philippines 6 November 2013. Image from US Naval Research Laboratory.

Typhoon Haiyan is the 11th typhoon to form in the west Pacific during an exceptionally active period in the last seven weeks. China, the Philippines, Vietnam, Japan and South Korea have all been struck by Haiyan’s predecessors. Furthermore, Cyclone Phailin, which developed in the Bay of Bengal, struck north-eastern India in October bringing damaging winds and storm surge. Accurate forecasts, combined with well executed warning and evacuation procedures, meant that the loss of life was relatively low.

It is almost a year since the devastating Typhoon Bopha hit the southern Philippine island of Mindanao causing much destruction and the loss of over 1,000 lives. Haiyan is a similar strength to Typhoon Bopha with winds near 160 mph – equivalent to a category 5 hurricane. Heavy rain, storm surge and mudslides will be an additional hazard as the typhoon makes landfall over the Philippine islands of Samar and Leyte on Friday.

Forecast track of Typhoon Haiyan from the Japan Meteorological Agency

Forecast track of Typhoon Haiyan from the Japan Meteorological Agency

Regional warnings for Typhoon Haiyan are produced by the Japanese Meteological Agency (JMA) and the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA). The Met Office routinely supplies predictions of typhoon 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 Unified Model and latest observed cloud cover and sea surface temperature. We also provide updates on current tropical storms via @metofficestorms on Twitter.

 





The severe storm this weekend and why it’s not a hurricane

26 10 2013

There is much coverage of the storm heading our way later this weekend with mentions of it being a ‘hurricane’. This is not strictly correct as we don’t get hurricanes in the UK and this is why.

Hurricanes are warm latitude storms; they draw their energy from warm seas and can only begin to form where the ocean is warmer than 26 degrees Celsius or so, and can really only become a major storm when the sea is warmer than 28 degrees Celsius. That’s like a warm bath, so you won’t find one around the UK anytime soon!

Other limitations, like wind patterns in the upper atmosphere and the forces caused by the Earth’s rotation, mean hurricanes are normally found in an area between 8 and 20 degrees north of the equator.

You can find a full explanation of what hurricanes are and how they form on our What are hurricanes? video

The storm which is due to develop tomorrow night and affect the UK during Monday is a mid latitude storm, the sort which affect us through the autumn and winter. These are formed in a very different way – by the meeting of different air masses on what is known as the polar front, leading to low pressure (storms) forming, often around the latitude of the UK.

The storm which is due tomorrow is expected to bring very strong winds and heavy rain, and we are warning of winds gusting 60-80 mph quite widely and locally over 80 mph, especially on exposed coasts, both in the southwesterly winds ahead of the low centre and west to northwesterly winds behind it.

Winds of that strength are classified on the Beaufort scale as ‘hurricane force 12’ but that is not the same as being a hurricane. Winds of this strength could bring down trees or cause structural damage, potentially causing transport disruption or power cuts and we are working closely with the resilience community to ensure they are prepared for the expected conditions.

You can find practical advice about what to do in winter weather on our Get Ready for Winter website.





Cyclones set to strike India and the Philippines

11 10 2013

While the tropical storm and cyclone season for the northern hemisphere has been relatively quiet this year, the last few weeks has seen a spike in activity with three tropical cyclones currently active.

The north Indian Ocean sees tropical storms develop during two periods of the year – April to June and October to December.

Cyclone Phailin at 0455 UTC 11 October 2013. Image from the NASA Terra satellite.

Cyclone Phailin at 0455 UTC 11 October 2013. Image from the NASA Terra satellite.

Cyclone Phailin formed in the Bay of Bengal earlier this week and has become the most intense cyclone in this region since Cyclone Sidr in 2007. At the time of writing it has 1-minute average sustained winds of near 155 mph.

Phailin, which is a Thai word for ‘sapphire’, is expected to make landfall over the Odisha state of India on Saturday night and bring destruction from its strong winds, heavy rain and storm surge.

It is likely to be the strongest cyclone to hit India since the devastating ‘Odisha Cyclone’ of 1999, and it is possible it could be even stronger.

Meanwhile Typhoon Nari is continuing a busy spell for tropical storms in the last few weeks in the west Pacific Ocean.

With winds near 100 mph, Nari is making landfall over the northern Philippines today before moving into the South China Sea where it could continue towards a second landfall in China or Vietnam.

Behind Nari, another storm is developing called Wipha. This is set to strengthen into a typhoon and move northwards in the direction of Japan.

Landfall over Japan is possible, but at this stage a glancing blow to southern coastal regions of the country in the middle of next week is the most likely outcome.

Official warnings of west Pacific tropical storms are produced by the Japanese Meteological Agency (JMA). Official forecasts of Indian Ocean tropical storms are provided by the Indian Meteorological Department.

For more information on tropical cyclones worldwide, visit our web pages or 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.








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