Just how fast will be crucial in deciding whether 2010 will be hotter than the hottest year on record, which was set in 1998, as defined by the UK Hadley Centre, The World Meteorological Organisation (WMO) and UAH Satellite data.

During a La Niña, trade winds in the western equatorial Pacific are stronger than normal, and the cold water that normally exists along the coast of South America extends to the central equatorial Pacific. This colder water directly translates into colder global temperatures, just as warm waters associated with an El Nino directly translates into warmer global temperatures.

The Last El nino comparable to this one in 1997/1998 was followed by a La Niña which began developing in the middle of 1998 - and was persistent into the winter of 2000. According to the Japanese institute for Marine Earth Science, the La Nina condition developing now might last for a longer-than-normal period.

If history repeats itself, not only could 2011 be much cooler than 2010, but that cool bias could extend into 2012 too.

The picture above illustrates how their global model sees the world surface air anomalies between Dec 2010 and Feb 2011. Note on average how much of the land is actually cooler than normal by that time.

The last paragraph of my latest blog seems to have aroused interest so for clarification this may be of interest.

ENDS

There's been some hot weather across some parts of Europe and America in the last few days.

The eastern US and parts of Canada are in the grip of a heatwave with soaring temperatures are affecting areas from Quebec to Virginia; the mercury hitting 39.5C (103F) in some places. Power cuts have occurred as energy usage soars, leaving thousands of households without power

Eumetnet, the public European weather services network within the World Meteorological Organization, has issued severe hot weather warnings for most of Spain, the western half of Germany, most of Belgium and parts of the Netherlands.

Temperatures in Berlin are expected remain at highs of 35-36 degrees Celsius until Monday, before cooling slightly in the middle of next week, according Germany's national forecaster, while Madrid is melting at highs of 40 degrees on Thursday, according to Spain's official forecaster, with highs of over 34 degrees into next week.

Here in the UK, the Met Office warned there was a 60% chance that somewhere in the Southeast could reach 32C for the first time this year.

From a global perspective, temperatures have been close to record levels in the first 6 months of the year.

The graph below shows that temperatures seem to have peaked very close to the values reached during the hottest year on record set in 1998.

In the first 6 months of this year, average global temperature anomalies according to satellite data were 0.565C above normal, compared with the first 6 months of 1998, when the figure was 0.64C.

The difference between the two is not statistically significant.

Met Office data also shows that global temperatures in the first half of 2010 have been close to record levels.

Global temperatures are expected to fall later this year, as El Nino fades fast, possibly replaced by La Nina conditions. Just how fast they fall will be critical in deciding whether, as the Met Office forecast late last year, 2010 becomes the hottest year on record.

A similar drop was experienced during the second half of 1998; 1999 was a cooler year and it is likely that 2011 will be cooler than 2010, too.

All this comes against a background of a continued very weak solar cycle which has gone on far longer than normal.

Those who believe that the sun plays a much bigger role in governing the level of global temperatures (as opposed to how it might affect weather patterns) could be forced to re-think their beliefs in the face of these high worldwide temperatures which are being measured by both conventional land and sea-based thermometers, and satellite data alike.

Across the UK it has been the driest first 6 months of any year since 1929.

And according to preliminary CET (Central England Temperatures) figures, it has also been the warmest June since 2006.

Looking back through the climate records, one thing stands out. Long periods of dry weather in Spring and early summer often means the rest of summer is much more unsettled. There are exceptions to this rule, like in 2003 and 1976 to name but two, but the odds are stacked against a continuation of dry and warm weather through the rest of summer.

And there is a reason for this.

The Jet stream, a ribbon of strong winds in the upper atmosphere, controls our weather and is responsible for Atlantic depressions and areas of high pressure, leading to wet and dry weather respectively.

The Rocky Mountains in North America act as a barrier to the jet stream, and as air blows across the mountain range, a series of waves are produced downstream.

When the jet stream is at its strongest, the waves pushing eastwards from this mountain range are flat. This is what we call a 'mobile westerly' with weather systems bringing rain, followed by a couple of days fine weather, and then another weather system, and so on. Typical British weather in fact.

But when the Jet stream is at its weakest, the waves are shorter, causing a series of much more pronounced peaks and troughs in a much more 'meridional' or north-south pattern.

In this situation, a ridge of high pressure can get stuck over the UK, leading to persistent dry weather, which is what we have had for the last few months. Conversely when a trough becomes established we can have weeks of wet weather.

Interestingly, the wavelength of these peaks and troughs in our atmosphere tends to get shorter as we head into summer. So if a ridge (dry weather) has dominated our weather in spring and early summer, it is likely to move westwards into mid-Atlantic, leaving the UK under trough (unsettled) conditions. And as we head through early July it is common for this weather pattern to remain for the rest of July and August.

Currently the pattern is certainly shifting, as the upper trough starts to position itself across the UK in the next few days, with weather systems bringing rain in from the west in a more typical mobile-westerly set up.

It's for this reason that the weather is expected to be much more unsettled during the first half of July. Only time will tell if this change will last for the rest of summer.

Averaged over England and Wales, June 2007 turned out to be the wettest since 1860.

The period in June 2007 that brought severe flooding to large parts of Yorkshire was the wettest 12 day summer period ever recorded in the county.

Interestingly June 1982 was even wetter than June 2007. But in 1982, heavy downpours were more evenly spread throughout the month whereas in 2007 the rain was concentrated in a much shorter time period, resulting in flooding that was far worse and more widespread than anything experienced in 1982.

I visited Filey earlier this week. The Muston road area has suffered flooding 3 times in 8 years: In 2000, 2002 and 2007 localised torrential rainfall left sewers unable to cope, leading to flash flooding of local properties.

It's becoming a common problem. This part of Filey used to be agricultural land. But the need for new housing has lead to extensive development. So when torrential downpours occur, the rainwater runs off much more quickly than it used to do, leaving local sewers overwhelmed.

Up and down the country, urbanisation is leading to more and more incidents of flash flooding, and it's often too easy for the media to blame it on climate change. It's true to say that if climate projections are correct for the UK, a warmer climate will lead to heavier rainfall. But urbanisation is a significant factor in the increased incidents of localised flash flooding.

Yorkshire Water, who are ultimately responsible for surface water drainage think they have come up with a solution - in Filey at least.

They've spent over £2 million pounds building a flood water storage tank that holds 1.1 million litres of water - by volume its half the size of an Olympic swimming pool and is designed to hold excess water that the sewers can't cope with until the storm abates, slowly releasing the water back into the sewer system when the rain stops falling.

It's a fear that many people who have been flooded have; every time it rains, will it happen again? After 3 floods in 8 years, the residents will be hoping that the next time a downpour affects Filey, they can be a little more relaxed about the risks of 4th flash flood hitting Muston Road.

Thanks to Quaesoveritas for highlighting the error in rainfall statistics. It has indeed been the driest start since 1953, not 1929.

ENDS

People in North West England are facing a hosepipe ban unless there's significant rainfall very soon, following the driest start to a year there since 1929.

But despite the geographical proximity to Yorkshire, according to Yorkshire Water, the situation here is much healthier. At the end of last week, water stocks were running at around 75%. So why, when we have had similar weather to Northwest England, are we not facing imminent drought orders here too?

This is because reservoirs aren't our only source of water - in fact this is where about ¾ of our drinking water comes from. The rest comes from bore holes in the East.

And the reservoirs in the West of our region are connected to the bore holes further East by an underground pipe network capable of pumping water from one part of Yorkshire to another.

And, if necessary, water can be pumped from some of the county's rivers, like the Ouse outside York, which are also connected to this underground pipe network.

This pipe network was laid as a direct result of the disastrous water shortage of 1995, which is still fresh in peoples' minds. Reservoirs were at healthy levels at the end of winter 1995, but a combination of a very dry Spring and Summer, coupled with a water pipe network that was in dire need of repair, meant that by the end of Summer the Nidderdale reservoirs, which supply water to Bradford, were within 10 days of running completely dry. Convoys of tankers brought millions of gallons water by road all the way from Northumberland to Scammonden reservoir in Calderdale in a desperate attempt to prevent stand pipes on the streets. It was a pr disaster for Yorkshire Water.

But it's thanks to the lessons learned by Yorkshire Water in 1995 that the county now has arguably the most reliable and robust water supply in the country. That said, if the dry weather continued into July and August, the authorities may come under pressure to follow the Northwest region in looking more closely at seeking a drought order.

Since December of last year, the atmosphere has been 'blocked', preventing the normal sequence of weather fronts moving across the UK. Instead, high pressure has been dominant, leading to a distinct lask of rainfall.

Although there is no sign that we are about to see a resumption of our more normal mobile pattern of weather anytime soon, it does look as though conditions could become much more unsettled towards the end of next week, meaning potentially much wetter conditions for parts of the UK.

The ECMWF (European Centre for Medium Range Forecasting) chart shown below for next saturday indicates low pressure in charge by that time.

Looking even further ahead, I thought the latest forecast temperature charts from NOAA (National Oceanic and Atmospheric Administration) were very interesting.

Note how virtually the whole of Europe through Autumn and next Winter is once more colder than average.

It's a long way off, but it suggests that weather patterns are likely to remain more blocked than normal across Europe. With average solar activity continuing to be weak, coupled with the likelihood of developing La Nina conditions (cooling of surface waters in the tropical eastern Pacific Ocean) later this year, the odds on a cold winter across Europe must once again be higher than normal.

Most, but not all, meteorologists dismiss the idea that the sun could play an important role in determining our weather, and hence climate.

This may, at least in part, be down to the fact that forecasts these days are heavily reliant on powerful supercomputers that can't incorporate the influence of the sun, simply because the precise mechanism of how the sun impacts our weather is either not understood, or impossible to model.

But it wasn't that long ago that eminent climatologists such as Professor Lamb at the University of East Anglia conducted research which showed, amongst other things, a link between low solar activity and pressure patterns over Greenland.

In his day forensic analysis of weather data was the only way to forecast the weather, but sadly much of his work, and work like it, has been mostly forgotton, as the weather industry becomes more and more reliant on computer simulations of the atmosphere.

But it seems that it may becoming a fashionable area of research once more.

In my article 'Could the sun cast a shadow on global temperatures' I featured research by Australian scientist David Archibald, who concluded that the prolonged solar minimum that we have just witnessed would lead to, amongst other things, colder European winters in the next decade.

Interestingly his research was published in 2008 long before the coldest winter in the UK since 1978/79 struck.

So it was with interest in April when I read that Professor Lockwood at Reading University conducted a similar analysis, and came to the same conclusion as Mr Archibald - that colder European winters in the next few years were possible because of the behaviour of the sun. You can see an article based on his research by clicking here.

But I wanted to highlight a fascinating piece of research that has been published in the Journal of Atmospheric and Solar-Terrestrial Physics. It again shows quite clearly a link between solar activity and temperature and pressure variability across Europe. You can read the research paper by clicking here, but here are some intriguing highlights:

1) A strong correlation is found between wintertime temperatures and pressure disturbances in Europe - which applies up to the most recent past and which, according to the authors, had not been previously reported.

2) The relationship between solar forcing and European climate is not stationary over a year, but strongly depends on the season, so simple averaging over the whole year may obscure the underlying forcing. The solar signature is present all over the 20th century in wintertime European temperature.

3) Solar modulation of temperature disturbances 'are by no means small'.

4) The authors believe they have uncovered a regional (European) expression of a global phenomena.

5) The study shows that the evolution of temperature disturbances remains linked with solar activity up to present.

6) Physical processes and feedbacks possibly linking climate variations to solar variations are not fully understood.

The authors conclude that 'the role of the sun in global and regional climatic change should be re-assessed'.

These high temperatures were all the more interesting when you consider it was only just under two weeks ago when I wrote that Leeming had recorded its coldest May night since 1967, and the second coldest on record, on the morning of Wed 13th May.

Other stations across Yorkshire have had similar extremes. At Pateley Bridge, which is not an official Met Office site but nevertheless an accurate station run by a local expert in the area, Sunday was the hottest since records began in that part of Nidderdale 27 years ago. Moreover, the contrast between the cold reported in Mid May, to this record heat, is a record in itself. The absolute temp range for this May at Pateley Bridge is 29.3C (-2.8C to 26.5C).

Hull in East Yorkshire also set a new record. Again, it's not an official station, but 29.4C (85F) was recorded on Sunday at a very reliable site run by a local expert. At the old Hull Met Office site, records which run from 1901 to 1971, the previous record was 27.8C. It's a remarkable temperature for a city on the Humber Estuary and so close to the influence of cold sea breezes at this time of the year.

But it's proved to be a very short lived hot spell. Indeed as I write, it's currently only 10C in the Vale of York as cool air from the Northeast makes a return.

For those still keen to know what the summer will be like, an interesting fact. As I wrote in my one of my previous blogs, there's been 23 cold winters since 1940; and only 2 have been followed by warm summers. That would suggest that although a hot summer is not impossible, it is certainly statistically very unlikely.

But one of the 2 years in which a cold winter was followed by a hot summer was in 1947. It's probably just a coincidence, but I found it interesting that Sunday was the hottest May day at Leeming since May 1947. Could history repeat itself, with 2010 following the same pattern as in 1947, with a warm summer to follow? Only time will tell.

Briefly onto global temperatures. I wrote in my last blog that global temperatures were high on all measures, close to the record values set in 1998.

The big question is how long will this heat last, and will it mean 2010 is the hottest on record, as predicted by the UK Met Office?

The graph below offers a few clues. It shows in blue the global ocean temperature anomaly, with the red line indicating the ocean temperature anomaly where the current El Nino has been occurring (an upwelling of warm water which adds to global temperatures). It shows a sharp drop off in the El Nino heat; with global temperatures starting to follow.

Several models are forecasting a La Nina developing later this year which would cause cooling. It's going to be a very interesting few months.

It is interesting that the current record was set very early in the month - making the recorded temperature last night all the more remarkable.

Church Fenton in West Yorkshire also had their coldest May night since 1967.

Although April was above average from a CET (Central England temperature measurement) point of view, May is now well below average, and as we approach the half way stage of 2010 it is becoming clear that there is going to have to be quite a turnaround in UK temperatures for the whole of 2010 not to be colder than average.

This comes against a backdrop of warm global temperatures, on all measures. In fact so far this year, global temperatures as measured by satellites are only just below those that were recorded in the hottest year on record, in 1998.

Across the UK, next week looks much warmer than of late, with a continuation of the mostly dry, anticyclonic theme. If the models are correct, May on the whole looks set to be a very dry month.

This blocked weather pattern has mostly been in place since mid December of 2009. From a climatological point of view, It could be only a matter of time before a wetter, more cyclonic West to South-westerly type of weather becomes established for the first time since November of last year.

I have been asked numerous times just how long we could be affected by volcanic ash.

Dr Dave McGarvie who is a Volcanologist at the Open University told me earlier today about what history can tells us about Icelandic volcanic eruptions in the past.

"The current volcano (Eyjafjallajokull) erupted for just over a year from December 1821 till early 1823. It didn't erupt constantly all this time though, as after a week or so of intense activity it just sent out occasional minor explosions until end-June 1822 - when another sequence of substantial explosive eruptions started and lasted for a month till early August. It was quiet from then on (occasional explosions) and activity gradually died out early in 1823.

On June 26, 1823 the bigger volcano next to it (Katla, 25 km to the E) erupted. This was a small eruption by Katla standards and lasted for 28 days.

Historical record (last 1100 years) shows that three times Eyjafjallajokull erupted Katla has erupted soon after (c.920 AD, 1612, and 1821-1823). But it could be pure coincidence! After all Katla has erupted 20 times in that same time period. And each of the Eyjafjallajokull eruptions were different, so there's no common thread there. But the volcanoes are close to each other, and the lavas etc from both volcanoes overlap on the surface, so there could be a subterranean connection. Bottom line - we don't know enough.

The last substantial Katla eruption started 12 October 1918 and lasted 24 days. It produced an eruption plume an estimated 14 km (46,000 feet) high. A nice little injection of ash into the stratosphere of course, with a different set of problems to what we experienced in mid-April.

Katla is Iceland's second most active volcano, after Grimsvotn which lies within the Vatnajokull glacier. Katla has a habit of erupting twice a century, so that's why the Icelanders are a bit anxious about the length of time that's passed since 1918 - and whether this might mean a bigger eruption is due. However there's no correlation between the length of time that's passed and the size of the eruption because (for example) both of the eruptions in the 1600s and in the 1700s were amongst the largest recorded."

According to the Met Office there was a report from the Outer Hebrides yesterday evening of a milky sky, and in the early hours Tuesday of volcanic dust was detected at 9000ft in the same location.

The latest projection shown below for 7am tomorrow morning shows most of Scotland and parts of Western England affected by volcanic ash, roughly from Newcastle through Manchester and south to Exeter - though of course it remains to be seen whether it's thick enough to affect air traffic.

The wind direction at 20,000ft is mostly from the north, shown below. This would mean that the area of ash across Scotland, and the area to the north of Scotland, may be dragged across other parts of the UK later tomorrow and into Wednesday.

Of course even if volcanic ash affects more areas tomorrow, it's again worth pointing out that it's the density of volcanic ash that is of critical importance. So more flight disruption is not a certainty, although it is certainly possible, in the next few days.

Not so these days. The Met Office may forever be associated with its 'barbeque summer' forecast - which, without the headline, would have in all likelihood passed off with very little fuss, like in the days of Bill Foggitt.

So it was with interest when I saw private forecasting company Positive Weather Solutions featuring heavily in the press last month, with headlines of a long hot summer, with a chance of a new record, beating the current hottest ever temperature, recorded in Faversham, Kent, in 2003, of over 38C.

Interestingly, a look at PWS's website shows a forecast that bears little resemblance to newspaper headlines at the time, although they do suggest record breaking temperatures in August are possible.

So what are the chances of such a scorching summer? I thought it was time I put my money where my mouth was and have a look to see if there are any clues as to what lies ahead.

Firstly, to an argument I have heard many times. Summers following an El Nino are good.

Looking back at the last 3 El Nino summers of 1998, 2003 and 2007 gives a very mixed picture. 2003 was a very warm summer, with a new temperature record established. But although April 2007 was the warmest on record, the summer that followed was poor, with serious flooding during widespread heavy rain which affected much of Yorkshire. Summer temperatures were close to average in 2007; identical in fact to summer temperatures in 1998, according to CET (Central England temperature) data.

So an El Nino does not seem to be a reliable indicator of summer conditions in the UK.

I then looked to see if there were any conclusions to be drawn from our very cold winter. What happened in the past, when winters across the UK were cold? I looked back over the last 70 years.

What I found was very interesting. It turns out that on very few occasions were cold winters followed by warm summers; in fact the vast majority of summers, over 90%, ended up with average or below average temperatures, following a cold winter.

And what about solar considerations?

The poor summers of 2007, 2008 and 2009 have all coincided with the protracted solar minimum that we are only now recovering from. Although activity is now picking up, it remains at a very low level (as measured by the number of sunspots).

Latest research suggests that the position of the jet stream is affected, at least to some extent, by solar activity, and low solar activity this summer could mean the jet stream is again on average further south than normal. This would not bode well for this summer.

This thinking is confirmed by Piers Corbyn, from Weather Action. He accurately predicted our prolonged cold winter, and last summers washout, and bases his forecasts on the way solar activity influences our atmosphere.

I spoke to him last week, and he is confident that this summer, because amongst other things solar activity is likely to be low, will not be a 'barbeque summer'. And there's no chance, he says, of breaking the current UK record for heat. Weather Action will be publishing a more detailed summer forecast in the next few weeks.

I don't pretend to be any expert in long range forecasting. But it would seem that there are enough clues out there to suggest what our summer might be like. It won't please the tabloid headline writers with an eye for a sensational headline, but here is my forecast.

Summer 2010: An average British summer, with some spells of fine warm weather, but with its fair share of cooler unsettled spells too.

And to those hoping for a long hot summer, like in 1976 or 1995, I say this. Don't hold your breath!

The Met Office has confirmed by observation the extent of atmospheric ash, with balloon observations showing a 600 metre deep ash cloud at an altitude of 4km across parts of the UK. Despite several airlines reporting no problems during test flights, NATO F-16 fighter jets have reported engine damage when flying through the volcanic ash.

The latest projections, shown below, issued by the Met Office, show virtually all of the UK except the Northeast of Scotland contaminated by ash at 7am Wednesday morning.

Upper winds are forecast to continue to blow from the Northwest for the rest of this week, indicating further plumes of volcanic ash heading towards the UK from time to time. Although further clearances are possible, the only significant prolonged clearance across UK airspace will not be until the weekend, when the wind switches to a West or Southwest direction.

It's likely to be a very frustrating week for all involved.

Latest charts for 1pm tomorrow afternoon show the clearance continuing to move south-eastwards at that time, with areas from the Midlands northwards in the clear. However the next plume of ash (seen on the satellite picture at the bottom of this blog) is pushing back in from the Northwest, covering the Irish sea, Western Scotland and much of Ireland by that time, suggesting that any lifting of air space restrictions in the morning could be short lived.

Volcano Update 3: Mon 19th April 2pm

Latest forecast charts issued by the Met Office this afternoon for 7am Tuesday morning show a clearance coming in across much of Scotland, but with England, Wales and much of Ireland still affected. This could mean Scottish airspace is reopened first thing tomorrow, although the relevant authorities will be making a decision shortly.

Looking at the wind streamline diagram below for tomorrow, which essentially shows the direction of the wind at around 20,000ft, shows that this clearance could make further progress south-eastwards across England. But any new ash from the Icelandic volcano is likely to be blown back towards the UK, leaving any window possibly short lived. No significant change to this upper level wind direction is expected until next weekend.

Reports this morning from the Icelandic Met Office indicate that the volcano is active this morning, spewing more ash into the atmosphere. This can be seen clearly on this morning's satellite picture, a red plume leaving the Icelandic coast.

And some beautiful volcanic sunsets to share with you from this weekend

The frustrating news for those wanting to fly is that according to the very latest forecast, issued in the last 15 minutes, much of England still has ash at around 20,000 ft at 7am tomorrow morning. However, the projection below though shows a definite clearance through Scotland and Ireland with parts of the North of England starting to see a clearance too.

Although ash projections further ahead are not produced by the Met Office, upper level wind forecasts still indicate that an improvement across the country is likely through Saturday, but with potential ash problems should the volcano still be active later on Sunday and into Monday.

It's also worth pointing out that even if the UK sees a clearance through Saturday, there are still large parts of Central and Northern Europe that may still be affected by ash, with obvious potential knock on effects for flight paths crossing these areas.

On a brighter note, for those lucky enough to have clear skies this morning, there's been some vivid 'volcanic' sunrises across our area.

With clearing skies tonight, this evening's sunset could be spectacular

UPDATE 7pm Friday 16th April

Latest update just to hand indicates for 1pm tomorrow much of Northern England in the clear, along with Ireland and Scotland, but the rest of the UK and much of central and Northern Europe still affected by volcanic ash - overall very little change.

Jet2.com's decision to cancel all flights tomorrow is understandable. Although some of the airports it operates from in the North of England may be in the clear during tomorrow, most of their planes would have flight paths through the ash across Continental Europe. It's an indication that disruption may continue into next week for many of the UK's airlines.

Upper level wind forecasts remain the same, with North or North-westerly winds becoming re-established at 20,000ft later on Sunday, so if the volcano continues to be active there's a risk of fresh ash into early next week.

UPDATE at 8am, Saturday 17th April

Latest projections, taking us to 1am Sunday morning again show very little change in the overall position of the plume at 20,000ft. If anything, the plume is seen creeping back northwards towards the Scottish border - and it now covers more of Europe, sinking into parts of the northern Mediterranean. (Sorry for no diagram but I am updating this from home and can't reproduce it)

UPDATE 1pm Saturday 17th April

New projections just in show all of UK and Ireland airspace with ash at 20,000ft at 7am Sunday morning, with the current window of clear air across Scotland and Ireland contaminated by ash again by that time. This implies air space that is currently closed will remain closed until at least 7am on Sunday, with Ireland and Scotland likely to see their airpace closed to aircraft once more - it also suggests there may not be much change through much of Sunday either.

Upper wind forecasts still show if the Iceland volcano continues to erupt, fresh ash could be dragged across the UK through next week.

UPDATE At 7pm Saturday 17th April

Latest forecast shows virtually no change up until and including 1pm Sunday afternoon, with all of the UK and Ireland's airspace affected by ash - together with nearly all continental Europe, with the exception of Mediterranean countries. The plume also now affects areas to the West of Ireland, well into Mid Atlantic.

UPDATE AT 7.15PM ON SUNDAY 18TH APRIL.

Forecast just issued by the Met Office for 1pm Monday afternoon shows all of UK airspace still contaminated by volcanic ash, with very little overall movement. The areas affected do seem to be getting slightly smaller but there is still a wide area surrounding the UK that is affected. The Meditteranean, Spain and Portugal are clear.

Upper level winds into next week are still likely to be Northwesterly, bringing a risk that any fresh volcanic ash could spread Southeastwards towards the UK.