First hurricane for Florida since Wilma ten years ago

26 08 2015

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

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

Image courtesy of National Oceanic and Atmospheric Administration

Image courtesy of National Oceanic and Atmospheric Administration

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

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

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

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





Typhoon heads for Japanese volcano

23 08 2015

Typhoon Goni, which was located just east of Taiwan on Sunday morning, is expected to track across the western side of Kyushu Island in SW Japan through Monday.  There is a risk it could bring up to 200mm of rainfall in 24 hours across Kyushu, leading to a risk of flooding and landslides along with the threat of Hurricane Force winds and a storm surge.  This comes as the Japanese Meteorological Agency issues a level 4 alert for a major volcanic eruption on Mount Sakurajima.

Mount Sakurajima is one of 16 ‘Decade Volcano’ around the globe, meaning that it is a potentially destructive volcano close to populated areas. The level of alert suggests that the local population should prepare for evacuation, which would be made more difficult by a Typhoon impact.

Satellite image courtesy of National Oceanic and Atmospheric Administration

Satellite image courtesy of National Oceanic and Atmospheric Administration

Typhoon Goni has already bought heavy rainfall and Typhoon strength winds across the NE tip of Luzon in the northern Philippines.  Goni is expected to remain a Strong Typhoon (equivalent of a Category 2 Hurricane) with sustained winds of 80 knots and gusts to 115 knots, tracking steadily north through the rest of Sunday and Monday across the eastern East China Sea.  There is a risk of a storm surge and coastal flooding up through Kagoshima Bay in southern Kyushu.

Once Goni passes across western Japan, it is likely to lose its tropical characteristics, but could still bring flooding rains to the Korean Peninsula on Tuesday.

 





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.





Powerful super-typhoon heads for Philippines

1 04 2015

There is currently a super typhoon in the western North Pacific called Maysak. This is a particularly strong storm for the time of year with winds in excess of 160 mph. The strongest storms in this region usually occur between August and October. Tropical storms, including typhoons, are reliant on sea surface temperatures for their energy, and as the northern hemisphere has just moved from winter to spring, this is the coldest time of year for sea temperatures. However, in the region where Typhoon Maysak formed just north of the equator, sea temperatures are almost always above 26°C, which is the critical value for tropical storm formation. Furthermore, the sea temperatures are unusually warm in this area by more than 2°C.

Super Typhoon Maysak is the fourth tropical storm of the season in the western North Pacific, the others being Mekkhala, Higos and Bavi. There has not been a year with four or more tropical storms in this region forming before the end of March since 1965. Three of the four storms have been typhoons – only Bavi remained below the 74mph threshold (the sustained wind speed required to become a typhoon). There have never been as many typhoons before the end of March in the era of reliable records (since World War II). Maysak was also the strongest typhoon to develop in March in this region since Mitag in 2002.

Typhoon Maysak as seen from the MTSAT satellite on 1 April 2015 Image courtesy of digital-typhoon.org

Typhoon Maysak as seen from the MTSAT satellite on 1 April 2015
Image courtesy of digital-typhoon.org

Maysak has now started to weaken as it moves west-northwest towards the Philippines. However, Maysak is still likely to be a typhoon when it makes landfall this weekend. There is still some uncertainty over the exact track of the storm, but the most probable path suggests the Philippines’ northern island, Luzon, is most at risk – including the capital Manila. Wind damage and flooding are likely, particularly in coastal areas.

Typhoon Maysak on 1 April 2015. Image courtesy of the US Naval Research Laboratory

Typhoon Maysak on 1 April 2015.
Image courtesy of the US Naval Research Laboratory

The Eye of the Storm

Air sinks at the centre of a typhoon, resulting in the formation of an ‘eye’ which is sometimes free of cloud and mostly calm. However, on occasions small scale rotations can develop within the eye causing distinctive ‘mesovortices’ (small scale columns of rotating air) in the low level cloud pattern. These can be seen in this satellite loop of Typhoon Maysak created by the Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin:

http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2015/03/MAYSAK_H8VIS_064_31March_end0600_fast.gif

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 Maysak 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, as well as the latest observed cloud cover and sea surface temperature. We also provide updates on current tropical storms via @metofficestorms on Twitter.





Windy weather on the way

19 10 2014

As forecast, Hurricane Gonzalo made landfall over Bermuda on Friday with rain and winds of up to 110 mph causing power cuts, flooding, felled trees and damaged buildings.

The storm has continued in its journey since then, and passed the Canadian island of Newfoundland during Sunday morning.

The remnants of this tropical storm are being caught up in the westerly flow across the Atlantic and will be drawn towards the UK, crossing the country on Monday night and early Tuesday.

By the time Gonzalo crosses the Atlantic, however, it will be a very different system to the hurricane that affected Bermuda.

It will undergo what meteorologists call ‘extra-tropical transition’, which means it loses the warm-core typical of a tropical cyclone and becomes a much more standard Atlantic low pressure system – like we regularly see around the UK at this time of year.

As such the low pressure is expected to produce wind strengths and rainfall amounts which are not unusual over the British Isles during the autumn and winter months.

Whilst there is good confidence that this system will cross the UK on Monday night and Tuesday morning, there is still something to play for in pinning down the exact location of the strongest winds.

The Met Office has issued a weather warning for wind for much of the UK for Tuesday, particularly since the strongest winds look to coincide with rush hour for some locations, leading to possible travel disruption.

You  can see details of what to expect in the warnings page on our website. You can stay up to date with all the latest for the windy weather and what to expect for the rest of the week with our forecasts and warnings.





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.





Turning even warmer for parts of Britain

15 09 2014

After a disappointingly cool and wet August, September has been largely fine, with plenty of warm sunshine for many areas.

This has been thanks to an area of high pressure centred across the UK, which generally brings us dry and sunny weather.

Through this week, the high pressure will slowly move towards Scandinavia, with low pressure moving north towards southern parts of Britain.

This will introduce some isolated but potentially heavy showers in place. Cloud from the North Sea will also keep some eastern areas of the UK cloudier and cooler.

However, this low pressure will also drag in warm winds from the Mediterranean and France, causing a rise in temperatures across parts of the country.

Where we see cloud breaks and further sunshine through this week, we could see temperatures across parts of the south and west reach the mid 20s Celsius by day.

This is considerably warmer than the average of around 17C that we would normally expect across the UK for mid-September.

There has been some press interest about what effect Hurricane Edouard, currently in the Western Atlantic, will have on the UK’s weather.

It’s still early days, but computer models currently suggest the storm will move into the Mid Atlantic and then track south towards the Azores, well away from the UK.

This will mean that the British Isles will not be directly affected by the storm, and there is a hint that the largely fine weather will continue into the weekend to give us further settled weather.





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.








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