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.





Cyclone Evan strikes Samoa

13 12 2012

Towards the end of every year tropical storm activity moves from the northern hemisphere to the southern hemisphere. The South Indian Ocean has already spawned three tropical storms including the unusually strong early season Cyclone Anais in October. Attention has now switched to the South Pacific Ocean and Cyclone Evan.

Evan formed near Fiji a few days ago and moved north-east as it strengthened. As it reached the equivalent of hurricane intensity (winds near 75 mph) it made landfall over Samoa close to the capital city of Apia. Although winds of this strength are not exceptional for a cyclone, first reports indicate considerable wind damage and flooding from a storm surge of 12-15 feet (3.5-4.5 m). This storm surge is of similar height to that experienced in New York City during ‘Superstorm’ Sandy in October.

Visible satellite image of Cyclone Evan on 12 December 2012

Visible satellite image of Cyclone Evan on 12 December 2012

Although Samoa lies within the cyclone belt of the South Pacific Ocean, the island nation has been relatively storm free for many years. Cyclone Heta passed close by in 2003, but the last time Samoa received direct strikes from tropical storms was in 1997 and 1998 by storms named Tui and, coincidentally, Evan.

To make matters worse, Cyclone Evan is expected to become slow moving near Samoa and American Samoa, producing large amounts of rainfall, before turning back south-west. Latest forecasts suggest Evan will strengthen some more and could threaten a strike on Fiji early next week.

Regional warnings for Cyclone Evan are produced by the Fiji Meteorological Service. 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.

You can keep up to date with tropical cyclones around the world on our website or follow us on Twitter.





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. 





Tropical Strom Isaac likely to make landfall as Cat 2 Hurricane

27 08 2012

Tropical Strom Isaac was located about 120km WSW of Key West at 4am (UK time) on Monday 27 August, and continues to move west north west. Mean wind speeds of 65 mph 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 and forecast track of Tropical Storm Isaac from Met Office StormTracker

Satellite image and forecast track of Tropical Storm Isaac from Met Office StormTracker

The official United States National Hurricane Center (NHC) forecast track predicts an intensification of this system into a hurricane as it passes across the very warm Gulf of Mexico by midnight tonight with a high risk that the Hurricane will be a Category 2 storm, with winds of around 100 mph when it makes landfall along the US Gulf coastline during the early hours on Wednesday morning.

Official National Hurricane Center forecast for Tropical Storm Isaac

Official National Hurricane Center forecast for Tropical Storm Isaac

The NHC notes that there is still a great deal of forecast uncertainty in exactly where Isaac will make landfall, with locations ranging from the Texas/Louisiana border eastward to the Alabama/Florida border. The most likely forecast track has the eye of the storm making landfall close to New Orleans, but the NHC state that it is important not to focus on the exact forecast track due to forecast uncertainties and the fact that significant hazards extend well away from the centre.

Therefore, there is a high risk of very rough, chaotic seas and hurricane force winds across the Gulf of Mexico impacting marine traffic and oil and gas production during the next few days. This will be followed by torrential rain, potentially as much as 500mm in 48 hours, causing flash flooding. There is also the risk of embedded tornados and more general hurricane force winds, with a storm surge and over topping waves along the Gulf coast from Alabama to central Louisiana, with New Orleans at an increased risk of being impacted than previously expected.

The Met Office’s StormTracker allows you to monitor all named storms around  the globe to evaluate risk and enables the comparison of past and present storms. It can be used with the official warnings and guidance from the National Hurricane Center and other Regional Specialised Meteorological Centres (RSMCs) who have responsibility for the issue of tropical cyclone warnings.





Does the jet stream affect hurricanes?

16 07 2012

Many news and weather articles, including our own blog, have reported recently that the UK’s wet summer is caused by the jet stream being situated further south than usual for this time of year.

However, some have questioned whether there is a link between this and the hurricane activity seen so far in the Atlantic.

So how is the Atlantic hurricane season shaping up and has it been influenced by the weather at higher latitudes?

Atlantic hurricane season so far

The Atlantic hurricane season officially started on 1 June, but in 2012 it began early with two tropical storms, Alberto and Beryl, forming in May.

After a break of almost three weeks there were two more storms, Chris and Debby, in the latter part of June, with Chris becoming the first hurricane of the season.

Since then there has been another lull of almost three weeks in Atlantic tropical storm activity.

Has the Atlantic hurricane season been unusual?

In mid-July it is far too soon to make judgements about how unusual a hurricane season is likely to be based on activity so far. However, it was certainly unusual to see four tropical storms before the end of June as this has never been observed before in over 150 years of records.

The recent quiet spell in Atlantic hurricane activity is by no means unusual. Atlantic hurricane seasons are often characterised by bursts of activity followed by quiet spells.

The peak of activity usually runs from the second half of August through to October. Even in some years which turned out to be very active, early season activity was low.

For example, by this time in 2010 and 2011 there had been just one tropical storm. Each of these seasons ended up yielding a total of 19 storms.

Is the jet stream involved?

The jet stream which affects UK weather is much further north than where the majority of tropical storms develop and hence has no direct impact on their formation.

However, once a tropical storm develops and starts to move to higher latitudes the jet stream can influence where it ends up. For example, in September 2011 as Hurricane Katia moved northwards in the Atlantic it met a powerful part of the jet stream and was swept eastwards as a strong ‘post-tropical’ storm which brought stormy conditions to the northern UK.

Will it be an active hurricane season?

The Met Office seasonal forecast for Atlantic tropical storm activity issued in May predicted a near-average season with the most likely number of storms in the June to November period being 10. Since June two tropical storms have occurred so far (the two May storms fall outside of this prediction period).

One of the major influences on the season’s activity includes the existence of La Niña or El Niño conditions (natural cycles which affect sea temperatures in the equatorial east Pacific).

Having just come out of an extended period of La Niña conditions, forecasts suggests an El Niño could develop before the end of the current hurricane season.

This would suppress hurricane activity in the Atlantic by disrupting the airflow over the regions where they usually develop.

However, it is worth remembering that it is 20 years since the quiet El Niño influenced Atlantic hurricane season of 1992. Despite being a quiet season overall, it still managed to spawn the deadly and powerful Hurricane Andrew which brought devastation to parts of Miami in Florida.

For more information on tropical cyclones worldwide visit our web pages or follow @metofficestorms on Twitter.





How often do the remains of hurricanes affect the UK

9 09 2011

Hurricane Katia, currently in the western Atlantic is set to steam due east towards the UK and is expected to reach our shores as a post tropical storm later in the weekend. With it will come the risk of severe gales and heavy rain to parts of the UK. The strength and depth of this September storm is quite unusual, but similar storms that originated as hurricanes have affected the UK in the last 20 years several times.

Hurricane Bill – 2009

You only have to look back as far as 2009 to find a storm that crossed the Atlantic. Hurricane Bill formed on August 15th and reached the UK as a post tropical storm on August 25th, bringing severe gales and heavy rain two days after being downgraded from a hurricane to a tropical storm.

The path of Hurricane Bill in 2009. The storm crossed the Atlantic as a post tropical storm pushing into the UK and Ireland

 

Alberto, Gordon and Helene – 2006

In 2006, three post tropical storms reached the UK. Alberto, Gordon and Helene all brought wet and windy weather to the UK. Alberto combined with a cold front to the west of the UK whilst Gordon brought record warm temperatures as tropical air pushed north across the UK, but also strong winds that brought down power lines in Northern Ireland.

Isaac and Leslie – 2000

These two post tropical storms both affected the British Isles as in the year 2000.

Hurricane Karl – 1998

Hurricane Karl made its way to affect parts of southern Britain as a post tropical storm in 1998.

Hurricane Lili – 1996 

Perhaps the most similar storm to Katia was in 1996 when the remains of hurricane Lili pushed across the UK just one day after being downgraded from a hurricane. The post tropical storm ran across Britain on 28th and 29th October. The storm brought gusts in excess of 90 mph, bringing widespread impacts across the UK and causing significant disruption.

Path of Hurricane Lili in 1996

Hurricane Katia – 2011

Katia is currently a category one hurricane off the east coast of the US and will run across the Atlantic through the weekend bringing the risk of severe gales and storm force winds in places later on Sunday and through Monday.

Although it is expected to be windy everywhere, it is uncertain as to exactly which parts of the country will see the very strongest winds and therefore you should stay up to date with the latest forecast warnings.








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