Big waves and blustery winds for western coasts

3 08 2015

A low pressure system off to the west of the UK is generating some big waves which are set to affect western coasts through today and Tuesday.

Waves of between 2-4 metres (about 6-12ft) are expected through the peak of the swell early on Tuesday at exposed beaches in the South West.

There will also be some fairly strong winds tomorrow, with the potential for gale force gusts around coasts in western areas – which may make for difficult conditions for those camping.

With many people around the coasts for summer holidays, people are being urged to take care.

A spokesman for the RNLI said: “Large waves could make some normal coastal activities we take for granted significantly more risky; the force of surging water or breaking waves can easily knock you over and quickly and drag you out of your depth and once in the water it can be difficult to get out.

“Those particularly at risk from these conditions are walkers on beaches or harbour walls when the water is high; spectators looking at the waves who get too close; and anglers fishing from rocks or exposed headlands.  With a low pressure and high winds forecast, areas that you may have considered safe before could be underwater when large waves come ashore.

“If you are planning a coastal activity, our advice is to respect the water;  watch the shore from a safe distance and assess the conditions – think about the risk before deciding if  you need to go closer.”

The waves are the result of a low pressure which is currently to the west of Ireland. As it has been tracking across the Atlantic its strong winds have been generating large waves.

Pressure chart showing the location of the low pressure at 0100 HRS on Monday morning, where it is generating large waves which are heading for western coasts.

Pressure chart showing the location of the low pressure at 0100 HRS on Monday morning, where it is generating large waves which are heading for western coasts.

As the low gets closer to the UK it will track to the north of Scotland, but the waves it has generated will continue marching east towards our coasts.

The size of the waves on any given beach will depend on a number of local factors.

Tides are not particularly large at the moment, meaning the risk of coastal flooding is low for the next few days despite the big waves.

A spokesman for the Environment Agency said: “The flood risk is very low for the next few days. We always monitor the situation closely, working alongside partners, including the Met Office and local authorities, and issue alerts and warnings if required. People and businesses can sign up to receive these free flood warnings and to check their flood risk via our daily flood risk forecast and live Flood Warnings map.”

With British and Irish waters being dangerously unpredictable, the RNLI have just launched a new campaign ‘Respect the Water’ to raise awareness of hidden dangers around our coastline.

For more information on ‘Respect the Water’ visit http://rnli.org/safety/respect-the-water/Pages/what-is-respect-the-water.aspx





‘Super tides’, the weather and coastal flood risk

20 02 2015

UPDATED 27/02/2015 – this blog has been updated under the section ‘So what are ‘super tides” with the help of the National Oceanography Centre.

In this joint blog from the Environment Agency and the Met Office, we look at the issue of so-called ‘super tides’.

There has been a lot of media coverage about the potential impact of so-called ‘super tides’ which are due from today (Friday, 20 February) through to Monday.

So what are ‘super tides’?

Tides are governed by the gravitational pull of the moon and, to a lesser extent, the sun. Because the sun and moon go through different alignment, this affects the size of the tides.

When the gravitational pull of the sun and moon combine, we see larger than average tides – known as spring tides. When the gravitational pulls offset each other, we get smaller tides known as neap tides. We see two periods of spring and neap tides roughly every month.

Yet some spring tides are higher than others. This is because tidal forces are stengthened if the moon is closest to Earth in its elliptical orbit (astronomers call this perigee). Tide forces are also enhanced when the sun and the moon are directly over the equater. For ths Sun this happens on or around 21 March or September (the equinoxes). Spring tides are always higher at this time of year. The moon’s orbit also takes it above and below the equator over a period of 27.2 days. Just as with the Sun, the tide generating forces are at their greatest when the moon is directly overhead at the equator.

Very large spring tides occur when these astronomical factors coincide. Approximately every 4.5 years the moon is closest to the Earth, and is also overhead at the equator, at either the March or September equinox.

In some places, these extreme tidal conditions can cause water levels to be 0.5m higher than a normal spring tide, but the weather can have a greater impact than even these largest of tides

What is the role of the weather in sea levels?

It’s important to realise that just because we are expecting big astronomical tides over the next few days, these won’t cause the highest sea levels we’ve seen – even in the last few years. That’s because the weather can have a much bigger impact on sea level than the 18-year tidal cycle.

Strong winds can pile up water on coastlines, and low pressure systems can also cause a localised rise in sea level. Typically the difference in water level caused by the weather can be between 20 and 30cm, but it can be much bigger.

On the 5th December 2013, for example, the weather created a storm surge that increased the water level by up to 2 metres. Although an estimated 2,800 properties flooded, more than 800,000 properties were protected from flooding thanks to more than 2,800 kilometres of flood schemes. The Environment Agency also provided 160,000 warnings to homes and businesses to give people vital time to prepare.

This highlights the importance of the Met Office and the Environment Agency working together to look at the combined impact of astronomical tides, wind, low pressure and waves on flood schemes to assess the potential impacts for communities around our coast.

Will we see coastal flooding this weekend?

Given the height of the tides there may be some localised flooding. Weather isn’t playing a large part in water levels over the next few days, although strong winds on Monday are likely to generate some large waves and push up sea levels slightly. This is nothing unusual for winter. You can see more about what weather to expect with the Met Office’s forecasts and severe weather warnings.

The Environment Agency and the Met Office are working together to closely monitor the situation, and the Environment Agency will issue flood alerts and warnings as required.

In the Humber Estuary, for example, we are expecting total water levels of between 4.20-4.39 metres – well below record levels of 5.22m.

John Curtin, Environment Agency’s Director of Incident Management and Resilience, said:  “We are monitoring the situation closely with the Met Office and will issue flood alerts and warnings as required.

“It’s possible we could see some large waves and spray and urge people to take care near coastal paths and promenades and not to drive through flood water.

“However, we can only get a warning to you if you’ve signed up to our free service. People can also see their flood risk and keep up to date with the latest situation on the GOV.UK website at https://www.gov.uk/check-if-youre-at-risk-of-flooding or follow @EnvAgency and #floodaware on Twitter for the latest flood updates.”

For those in Scotland, you can see flood updates for your area on the SEPA website here.

For those in Wales, you can see flood updates in English and Welsh on the Natural Resources Wales website here.

You can also see John explaining the Environment Agency’s flood warnings here:





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.





Guest blog: RNLI lifeguards warn of beach dangers after winter storms

17 04 2014

Brett Shepherd, Lifeguard Manager, provides some timely advice for those planning a trip to the beach as the Easter weekend approaches.

As many of our RNLI lifeguards head back to British beaches this weekend, I’m hoping for some lovely weather to herald the start of the season. But the affect winter storms have had around the coast mean that many of the country’s most popular beaches are looking very different to this time last year.

Unprecedented storms over the winter have changed the make-up of some beaches, with sand dunes in some areas being washed away leaving sheer sand cliffs. On other beaches, access points to and from the beach have changed and shifting sand has left deep channels that in turn create strong rip currents.

Our RNLI lifeguards, who have been patrolling the country’s beaches since 2001, will be keeping visitors safe on 33 beaches across the UK over the Easter bank holiday weekend. Whilst we’re hoping lots of people head out to enjoy our glorious coast, there are a couple of easy safety steps we’re urging people to take following the winter storms.

Firstly, always head to lifeguarded beaches; they are far safer environments and will help offer you peace of mind. You can download a special ‘Beach Finder’ app from our website which will tell you where the nearest lifeguarded beaches are, or check with local authorities. We’d also urge people planning on visiting a beach to check local information in advance, as the beach environment may have changed dramatically since your last visit.

Swimmers should ensure that they swim between the red and yellow flags, which mark out the safest area to swim and are patrolled by lifeguards. Lifeguards are always on hand to offer beach safety information and advice, and please take heed of local safety signage.

By highlighting the dangers before visitors arrive at the beach, we hope that we can avoid potential incidents and everyone can enjoy their time on the beach in safety.

RNLI lifeguard rescue. Copyright Nigel Millar

RNLI lifeguard rescue. Copyright Nigel Millar





Strong winds, big waves and a storm surge

9 10 2013

A relatively deep area of low pressure is tracking past the north of Scotland today and is then expected to head south into the North Sea tomorrow.

This will bring some strong winds to northern Scotland tonight, then to the east coast of England tomorrow – particularly through the afternoon.

These northerly winds are expected to gust up to 50-60mph, which is unlikely to cause any wind damage but could generate some big waves in the North Sea.

Forecast surface pressure chart for Midnight tonight.

Forecast surface pressure chart for Midnight tonight.

The Met Office has issued a warning this possibility as the big waves could combine with a storm surge to overtop sea walls and potentially flood some coastal roads.

A spokeswoman for the Environment Agency said: “Strong winds and large waves could cause minor disruption along the North Sea coast on Thursday from Yorkshire to Essex. Spray and waves may overtop sea walls and people are urged to stay safe and avoid coastal paths and promenades. The high winds and localised flooding on roads could make driving conditions difficult in coastal areas.”

But what is a storm surge?

Essentially this is a very localised rising of sea level – independent of tides – related to the track of an area of low pressure (storm) and its accompanying winds.

The storm causes this surge of water in two ways. Firstly, strong winds push water in their direction of travel, causing water to ‘pile up’ on coasts facing into the wind.

The second element of a storm surge relates to differences in air pressure. Areas of low pressure are always relative, meaning the air surrounding them must be at a higher pressure.

These areas of high pressure push down on the surface of the ocean, forcing water towards areas of lower pressure to create bulges in the sea level. For each 1 hPa drop in pressure, sea levels rise by up to 1 cm.

Bulges move with a low pressure as it tracks across the sea. North Sea areas are particularly prone to storm surges because water flowing south cannot escape through the narrow Dover Strait and the English Channel.

When storm surges combine with higher tides and big waves they can cause localised issues along coasts.








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