One metre of rain to fall in the Bay of Bengal

29 07 2015

Parts of the Ganges Delta have already seen over 240mm of rain in just 24 hours and coastal areas to the north of the Bay of Bengal are expected to receive over 1000mm over the coming 48 to 72 hours. The area will also see some strong winds, with gust of up to 60mph along the coast. This severe weather is likely to have significant impacts with a risk of flooding, landslides and damage to infrastructure.

Satellite image of monsoons over Pakistan, Bay of Bengal, and South China

Satellite image of monsoons over Pakistan, Bay of Bengal, and South China

After a break in monsoon rainfall across parts of India through much of July, the region is now experiencing a more active phase. Over the Bay of Bengal, a deep monsoon depression has developed, bringing a period of prolonged heavy rain and strong winds to coastal districts of northeast India, Bangladesh and northwest Myanmar. A monsoon depression is an area of low pressure which brings intense rainfall, and with other ingredients in place, can develop into a tropical cyclone.

The monsoon depression is expected to remain slow moving, tracking into Bangladesh over the next few days before gradually moving west across northeast India over the weekend.

Unusually, this is one of three monsoon depressions affecting South Asia. As well as the monsoon over the Bay of Bengal there is a monsoon bringing heavy rainfall to northwest India and Pakistan with as much as 430mm of rainfall falling in 24 hours. A third slow-moving depression is also affecting northeast Vietnam and southeastern China. 543mm 718mm has fallen in 42 66 hours in Mong Cai City on the border between Vietnam and China, an area that was affected by Tropical Storm Kujira last month.

Elsewhere in the world, the hot dry conditions which have affected southern Europe through much of July have led to some wildfires in Catalonia, Spain, and the Provence region of France. There is expected to be some respite from the high temperatures across Spain and France though in the coming days as a cold front pushes in from the north bringing a risk of heavy showers and thunderstorms to northeast Spain and Southern France by the weekend.

 





Typhoon Nangka makes landfall over Japan

16 07 2015

In our blogs of 9 July and 13 July we described how the developing El Niño and a cyclical phenomenon known as the Madden-Julian Oscillation have combined to produce a period of high tropical cyclone activity in the Pacific. Nine storms developed inside two weeks – Linfa, Chan-hom, Raquel, Nangka, Ela, Halola, Iune, Dolores and Enrique. This is the highest number of Pacific tropical cyclones to form inside a two week period since 1968.

Typhoon Nangka on 16 July 2015. Image courtesy of The US Naval Research Laboratory.

Typhoon Nangka on 16 July 2015. Image courtesy of The US Naval Research Laboratory.

Typhoon Nangka formed almost two weeks ago close to the International Dateline and made a steady westward journey peaking in strength with winds of near 150 mph. It then turned north and started to weaken, but is now making landfall over southern Japan, still at typhoon strength.

Japan can sometimes receive several typhoon strikes in a season, but each time they bring much disruption and some destruction through a combination of wind, surge and rainfall. It is often the rainfall that can be most devastating as the typhoon draws huge amounts of moisture from the warm tropical ocean and deposits it over land.

Kamikitayama in southern Honshu has recorded 438.5 mm (17.3”) rain in a period of 24 hours and this is before the eye of Typhoon Nangka has even made landfall. It is possible that some locations could record over 600 mm of rain by the time the typhoon has passed. To put that into context, that’s more than the yearly rainfall for some parts of east England.

Typhoon Nangka Radar Image at 1255 (UK time) 16 July 2015 showing rainfall intensity. Image courtesy of The Japan Meteorological Agency.

Typhoon Nangka Radar Image at 1255 (UK time) 16 July 2015 showing rainfall intensity. Image courtesy of The Japan Meteorological Agency.

As Nangka crosses the islands of Shikoku and Honshu it is expected to weaken, but continue to produce heavy rain. Once over the Sea of Japan, Nangka is likely to make a rightwards turn and so could affect parts of northern Japan before finally dissipating.

Official warnings for the latest tropical cyclones in the western North Pacific are produced by the Japan Meteorological Agency. 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. We also provide updates on current tropical storms via @metofficestorms on Twitter.





Multiple tropical cyclones in the Pacific

9 07 2015

The Pacific Ocean has seen a lot of early season tropical cyclone activity with a total of 11 cyclones forming before the end of June. This included some intense systems such as typhoons Higos, Maysak, Noul and Dolphin in the west Pacific and hurricanes Andres and Blanca in the east Pacific.

After a brief respite, early July has seen the development of further tropical cyclones across the Pacific Ocean triggered by a cyclical phenomenon known as the Madden-Julian Oscillation (MJO). The MJO is a pulse of cloud and rain which works its way eastwards around the globe in tropical regions. It often is seen to start in the Indian Ocean before crossing into the Pacific Ocean and occurs on a timescale of 30 to 60 days. The magnitude of the MJO will vary, but the event which moved into the western Pacific early in July has been very strong. A strong MJO produces conditions which are very conducive for tropical cyclone formation.

At the start of the month, the MJO event resulted firstly in the spinning up of twin cyclones – storms either side of the equator at the same longitude. Chan-hom formed in the north Pacific, whilst Raquel developed south of the equator. Raquel brought unseasonal heavy rain to the Solomon Islands before dissipating.

Left to right - Typhoons Linfa, Chan-hom and Nangka on 9 July 2015. Image courtesy of The National Institute of Informatics.

Left to right – Typhoons Linfa, Chan-hom and Nangka on 9 July 2015.
Image courtesy of The National Institute of Informatics.

Chan-hom has continued to develop into a typhoon and has been joined by Typhoon Linfa to the west and Typhoon Nangka to the east as seen in the satellite image.

Linfa has just made landfall over southern China and is expected to bring stormy conditions to Hong Kong in the next day or so. Chan-hom is expected to pass close to the Japanese island of Okinawa before making landfall over eastern China. Nangka is currently over open ocean, but could affect south-western Japan in a few days time.

The tropical cyclone activity does not end there, however. As the MJO event moves east it is set to trigger more tropical cyclones in the central and eastern Pacific. Tropical Storm Ela has already formed and is set to pass just north of Hawaii in the next few days. There is also the indication from computer forecast models that one or two more tropical cyclones could develop in the eastern side of the Pacific in the next week.

The strong westerly winds associated with the latest MJO event are helping to enhance the developing El Niño by pushing warm waters in the western Pacific towards the east. A strong El Niño tends to promote tropical cyclone activity in the Pacific whilst suppressing it in the Atlantic.

Conditions are very unfavourable for the development of tropical cyclones in the Atlantic at present and we expect this to continue for much of the season. However, whilst activity is expected to be below average, this does not exclude the possible development of a few hurricanes in this region during the remainder of the year. Meanwhile, the Pacific is expected to see continued above average levels of tropical cyclone activity.

Official warnings for the latest tropical cyclones are produced by the Japan Meteorological Agency and the Central Pacific 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. We also provide updates on current tropical storms via @metofficestorms on Twitter.





Predictions of a below average Atlantic hurricane season

21 05 2015

The Met Office Atlantic tropical storm forecast for 2015 is for eight tropical storms between June and November, with a 70% chance (the ‘70% range’) that the number will be in the range six to ten. This is below-normal relative to the 1980–2010 average of 12 tropical storms.

The forecast number of hurricanes — tropical storms with winds of at least 74 mph — is five (70% range three to seven); the average number of hurricanes is six.

Tropical storm Ana on 8 May 2015 as it approached the South Carolina coast. Credit: NASA Earth Observatory

Tropical storm Ana on 8 May 2015 as it approached the South Carolina coast. Credit: NASA Earth Observatory

The forecast Accumulated Cyclone Energy (ACE) index — a measure of the strength and duration of storms over the season — is 74 (70% range 40 to 108); the average ACE index is 104.

The North Atlantic hurricane season typically runs from June to November, but has already seen one tropical storm (Ana) make landfall in South Carolina.

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

Forecast centres around the world have now declared that an El Niño has begun in the tropical Pacific.

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, so how this develops will be important for the storm season ahead.”

While it is still too early to determine with confidence how strong this El Niño might be, forecast models from centres around the suggest this El Niño is likely to strengthen during the coming few months.

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

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

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





Active tropical storm season in the Northwest Pacific as another typhoon heads for the Philippines

7 05 2015

Typhoon Noul is currently to the east of the Philippines in the Northwest Pacific, and is heading steadily west-northwest. Noul is expected to continue moving towards the Philippines whilst intensifying further to a very strong typhoon. The storm is expected to make landfall in the Philippines this weekend.

Noul pacific sat pic

There is still some uncertainty in the exact track, but currently Noul looks likely to make landfall on the east coast of Luzon, bringing very strong winds with gusts of 130kt (150mph), coastal and inland flooding with total rainfall accumulations of up to 400mm possible, and potential landslides across large parts of northern Luzon. There is also a risk of significant impacts in Manila if Noul takes a slightly more southerly track.

Track from Japan Meteorological Agency

Track from Japan Meteorological Agency

Although the typhoon is expected to weaken next week, Noul could also bring some heavy rain to parts of Japan.

This is the sixth tropical storm of the north-west Pacific season and the fourth to become a typhoon, which is an unusual level of activity so early in the season. And yet another tropical storm looks set to develop behind Noul, possibly following a similar path.

The Met Office works closely with counterparts at the Philippines weather service PAGASA, providing the latest information on computer model predictions of the likely track and intensity of Typhoon Noul as it nears the country.

Official warnings of west Pacific tropical storms are produced by the Japan Meteorological Agency. 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 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.








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