91Èȱ¬

Current Forecast Emphasis (Latest update: Sat. 26 June, 21:50hrs BST)

As indicatedÌýinÌýmy previous forecasts, Glastonbury 2010 continues on a settled and hot note for Saturday and Sunday.ÌýDry weather has prevailed since last weekend at Pilton and the parched groundÌýisÌýnow set toÌýremain underfoot until the end of the festival.

Overnight temperatures at Worthy FarmÌýwillÌýremain very comfortable between now and Sunday: by dawn, falling to low double figures (10-12C). It'll stay dry andÌýsettled nocturnally between now and Sunday night, with some local mistiness by dawn.ÌýÌý

The Glastonbury forecast offers this type of fine, settled and very warm weather into the weekend, with just a very small chance ofÌýshowers (Photo: Matt Cardy / Getty Images)

High pollen counts and -Ìýas you'd expect -Ìýhigh UV levels will remainÌýa feature into Sunday's fine weather.

ItÌýwill continue the dry, largely sunny and very warm theme experiencedÌýon Saturday,Ìýas a southerly drift up into the British Isles keeps temperatures high across all of southern England. Much as we saw on Saturday, expect a maximum by mid to late afternoonÌýaround 26-28C, withÌýa veryÌýlow chance (<10%)Ìýof showers. So, it's very likely that Glastonbury 2010 will enjoy dry, fine conditions right through to it's conclusion.

And how I wish I was there to see Stevie Wonder - my muscial hero (and his brilliant bassman, Nathan Watts... will he also be on stage? Please let me know!).

Enjoy - and thanks to all of you who have been visiting the blog this past week.

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Daily Summary:

WEDNESDAY: Dry, very warm and sunny. Max temp. 25C. Wind light SW

THURSDAY:Ìý Rather cloudy, misty start. Sunny spells then developing; small chance of a light shower. Humid feel. Max temp. 22C. Wind light WNW

FRIDAY: Early mist quickly clearing; sunny, dry and warm. Max temp. 25C. Wind light-moderate WNW.

SATURDAY: Sunny andÌývery warm / hot. Chance of showers very low (<10%). Max temp 28C. Wind light WSW.

SUNDAY: Sunny and very warm / hot. Chance of showers very low (<10%). Max temp 28C. Wind light SSE.

MONDAY: Sunny spells and very warm.Max temp. 26C. Wind light W.

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Quick Links:

Glastonbury Forecast summary

(with zoom function, via MeteoGroup)

(EUMETSAT/DWD via sat24.com)

Live Webcams (via 91Èȱ¬)

official website

91Èȱ¬ Glastonbury Festival website (includes TV/Radio schedules)

local news / travel updatesÌý/ links to local & regional radio & TV

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Valencia, 25-27ÌýJune 2010 (Round 9)

(This forecast will be regularly updated. This entry: SundayÌý27 June, 11:50hrs BST)

Quick Links:

• Ìý(via Agencia Estatal de Meteorología)
• (EUMETSAT/DWD via sat24.com)

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Nowcast Updates:

Sun. 12:55BST: Increasing cloud from the south, courtesty of the feature edging north (described below). Along the Costa Blanca south of Valencia (Benidorm and environs), it's now producing some isolated showers coastally and somewhat inland.Still worth keeping an eye on these developments albeit main thrust of any PPN remains offshore edging NNE.

Sun. 11:50BST: A dry, fine start in Valencia today, albeit the cumulus clouds forming in skiesÌýabove the circuit areÌýoffering aÌýhint of increasing mid-level destabilization. It's because to the south, an area of forcing moving northwardsÌýis producing a thundery cluster presently developing offshoreÌýthrough the Catalon SeaÌýinto Ibiza (very evident on satellite -Ìý see link above). It's recently showing signs of furtherÌýconvective developmentsÌýup through the Costa Blanca itself. The main thrust takes a NNE trajectory just offshore away from Valencia and so any risk of showers still remains small (as noted in previous updates)Ìýthrough the race window. Nonetheless, it's worth keeping a eye of the satellite / radar links above....certainly can't offer a cast-iron guarantee of totally dry weather this afternoon, albeit this remainsÌýhighly probable for the race itself.

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Forecast Headlines:

(PPN = Precipitation)

Friday:ÌýSunny;Ìýchance of PPN 35%. ÌýMax 26C. Winds moderate ESE.

Saturday: Sunny; chance of PPNÌý30%.ÌýMax 26C. Winds moderateÌýESE.

Sunday:ÌýSunny;Ìýchance ofÌýPPN 35%. Max 26C. Winds moderate, SE.Ìý

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Fernando Alonso tackles the Valencia street circuit in the Renault during 2009's event. After a strong showing in Montreal, he's upbeat about his chances forÌýthis year's European GPÌýin the Ferrari. Dry, sunny weather will prevail (Photo: AP / Alberto Saiz)

Synopsis and Forecast Emphasis:

After rather dull races for the past two years, I'm sure many fans would crave for a spell of wet running to enliven the spectacle at Valencia's street circuit. If so, you might well be disappointed with this weekend'sÌýforecast...

However,ÌýI think this year's race could wellÌýprove a good deal better in any case - not least given the tight level of competitiveness we've witnessed in some very compelling races this season.

Dry or mostly dry conditions areÌýexpected across Valencia each day for this year's event,Ìýwith a low (typically <40%) collective chance of showers from Friday to the end of Sunday.ÌýA thermal low has developed across peninsular Spain, delivering some hefty showers and thunderstorms inland where they'll continueÌýas the weekend progresses. However, theÌýprecipitation signal from various model ensemblesÌýremainsÌýfairlyÌýlow for Mediterranean coastal districts of SpainÌýand similarly acrossÌýValencia itself. So albeit showers are possible, they're unlikely.

Each day will see some very warm conditions in periods of strong sunshineÌýas temperatures readily climb to the mid to high 20's C and track temperatures doubtless way up into mid 40'sC+. Winds will remain mostly light during the morning, but with moderate sea breezes then developing into the afternoon.

In turn, these sea breezes could - if conditions are favourable -Ìýoffer a convergence zoneÌý'strip'Ìýinland whereÌýsome towering cumulus clouds will tend to grow and offer anÌýincreased shower potential by evening. It's not impossible that some evening and overnight showers could appear over Valencia, albeit this remains a low point probability.

The UK Met Office's MOGREPS ensemble modelling has offered around a 40% chance of precipitation (effectively as light showers)Ìýat some stage across Valencia and environs during the weekend, with greatest focus on Friday and Saturday. Spanish probability of precipitation (PoP) models are in agreement,Ìýoffering a collective rainfall chance around 15-40%, peaking on Friday and with the driest signal for Sunday. The GFS ensemble also paints an essentiallyÌýlow rainfall probability.ÌýAll the NWP products agree on keeping the greatest shower potential a good deal further inland, especially into northern-central parts of Spain. Early Friday morning, some showers have been skirtingÌýtowards the Costa del Sol as a small area of forcing migrates northeastwards; this will tend to offer some convective developments into parts of the Costa Blanca later and still a small potential for showers.

UPDATE: Wednesday 16 June, 19:00hrs BST:
It's rare that I'd want a forecast to be wrong, but the events unfolding in France have, tragically,Ìýmatched our worst expectations and represent the extremely dangerousÌýconditions anticipatedÌýin the entry I'd written on Tuesday afternoonÌý(below).

With torrential rain and resultant flash flooding proving a major hazard, at least 19 people have been confirmed as losing their livesÌýin the appauling weather endured across parts of southern France. It's not the end of this particular event, so further perilous conditions are expected for another 24hrs or so, including across parts of France, northern Spain, northern Italy and the Alpine region.

Our gives an update on the situation as of now, as does - graphically -Ìýthe video below.

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(Original Entry from TuesdayÌýfollows)

It's looking highly likely thatÌýa spell ofÌýexceptionallyÌýnasty weatherÌýwill affect some parts of Europe over the next 48 hoursÌý(Tuesday-Thursday).

Through parts of southern France, northern Italy and across a swathe of the Alpine region, the stage is set for a genuinely extreme event, with rainfall expected to reach some 200 to 300mm throughout the period across much of this area. It's by no means impossible that some districts could see a deluge eventuallyÌýtotalling a staggeringÌý500mm (half a metre).

Either way, those sorts of rainfall accumulations, over a fairly short period of time andÌýacross terrain with steep run-offs into river catchments,Ìýare bound to lead to some veryÌýdangerous and newsworthyÌýconditions.

So why is this happening?

As I write, there's a strongÌýupper vortex drifting down through the southern Bay of Biscay and rotating eastwards across northern Spain. In the next 24hrs, it'll swing northeast into southern France and towards the Alpine region.

Coupled to this upper air process, a plume of some very warm air, originating across North Africa, is advecting northwards. During Wednesday, it will engage with the upper vortex across the NW Mediterranean and into adjacent areas of southern France and northern Italy - a very potent cocktail, from which we'll see the generation of heavy rainfall and a threat of severe thunderstorms.

The Met Office synoptic chart (below) for midnight (GMT) Tuesday night intoÌýWednesday illustrates the complex surface dynamics at play.

Some very heavy rain is already starting to feed north off the Mediterranean andÌýaffect parts of France, includingÌýnear the likes of Nice and Monaco. You can keep an eye on this developing situation through .

Montreal, 11-13ÌýJune 2010 (Round 8)

(This forecast will be regularly updated. This entry: SundayÌý13 June, 15:30hrs BST)

Quick Links:

• (via Environment Canada)
• (via Environment Canada

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Current Forecast Headlines:

(PPN = Precipitation)

Emphasis: No significant change from last update. Dry or mostly dry raceÌýexpected with low % chance of isolated showers during the afternoon, especially later.

NOWCAST UPDATE: Note McGill (Montreal) radar is currently tending to pick-up spurious light-rate returns with no ground truth observationsÌýto support falling PPN at this stage. Some small isolated showers are, however, forming further west and NW, as evidenced periodically .

Friday:ÌýO'cast; a few sunny spells;Ìýchance of PPN 10%. ÌýMax 22C. Winds light SW.

Saturday: Rain clearing AM; chance of PPN later,Ìý30%.ÌýMax 23C. Winds moderate, ENE.

Sunday:ÌýPartly cloudy with sunnyÌýspells;Ìýchance ofÌýPPN 30%. Max 25C. Winds light, E.Ìý

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I noticed a comment written on a web forum, regarding the lastÌýrace weekend forecast in Turkey:

"It's easy: Sunny and dry," this person wrote.Ìý "....so why bother with forecasts when it's just so obviously going to stayÌýdry?"

Well, it may have seemed that way, but the 'very small risk of showers' highlighted in my blog that day was added because not all the forecast models were so bullish on keeping things 100% dry.

Indeed, during the race, a towering cloud -Ìýand associated moderateÌýshower - formed close to the circuit.ÌýAs it happened, itÌýwas the only one within a radius ofÌýmany miles, butÌýproved just how tricky offering this sort of site-specificÌýforecast detail can be!Ìý It'sÌýall the tougher, of course, when forecasting ahead for a local weather window of only a mere couple of hours.

So, let's see how well the forecasts square with reality this time around! Off we travel to the fantastic in Montreal, thankfully reinstated to this year's race calendar after an absence in 2009 - the first time it had been dropped since 1987. It's a race that has often become something ofÌýa Safety Car showcase and equally, one where inclement weather has proved an important component in the track action here on the .

Forecast emphasis and synoptic evolution

Summary:ÌýAlthough much of southern and midwest USA willÌýbeÌý, Montreal will seeÌýmaxima remain closer to seasonal norms, or slightly above into the weekend.

A far lessÌýless progressive advance of very warmÌýconditions up into Canada has been the solutionÌýfavoured by two modelsÌý(ECMWF and UKMO-GM) all week. Both keep the heat ridge away to the SW and theÌý(US) GFS model, originallyÌýfar more bullish in heating things up, has nowÌýdrifted into better agreement. Expectations are thusÌýfor temperatures to rangeÌýinto the mid 20's C through Friday-Sunday, with increasing humidity during the weekend, too.

As a fairly weak ridge of high pressure develops through Thursday night fromÌýHudson Bay southeast to the eastern seabord of the USA, the prospects forÌýFriday's on-track action during Free Practice 1 and 2Ìýlook rather cloudy but dryÌýafter what could be a rather foggy start in some districts around Montreal and the St Lawrence valley.

However,Ìýas the upper level WNW flow then establishes and persistsÌýinto the weekend, we'll see a threat of more disturbed conditions being fedÌýeastwardsÌýthrough Ontario, WisconsinÌýand other districtsÌýadjacent to the Great Lakes.

Ìý US NOAA-NWS rainfall accumulation prediction, above, for Saturday is indicative of potential for rain during the morning and showers during free practiceÌý3Ìý& qualifyingÌýin Montreal (red dot).

Saturday heralds an increased threat of wet weather, enhanced collectively in outputÌýover the past 48hrsÌýfrom the model ensemble. Rain associated with a frontal boundary edges southeastwards through Ontario and Quebec this morning, as it runs through Montreal and south across the US border into Vermont and environs. This will wash the circuit back to 'green' conditions. Thereafter, it'sÌýall about the condions left in it's wake. suggests the rain clears southwards ahead of FP3, with a few showers thenÌýjust about possible into the afternoon, coupled to some brighter spells slowly developing.Ìý

In a rather complex sandwich on Sunday, high pressure is building to the north around Hudson bay;Ìýan upper trough sinking southwards from east-central Canada;Ìýa quasi-stationary warm front sitting much further south; and a low pressure systemÌýapproaching eastwards over the northern Great Lakes later during the day, swept-up within the prevailing flow around the high pressure to the north of Montreal.

Cloud will tend to increase steadily during the day as the influence of the approaching low becomes more evident.ÌýFor the most part, there's a general lack of major forcing (e./g., absence of nearby frontal influences). The threat of rain will increase overnight and into a distinctly soggy looking spell through Monday.

So, a low chance of showers this afternoon. I anticipate the 'centre of gravity' for the threat of deeper convection toÌýbe held further southwards /Ìý westwards.

Dry weather looks the statistical likely outcome for the race,Ìýwith Probability of Precipitation (PoP) predictive model solutions still ranging 30ÌýtoÌý40%. With increasing cloud, someÌýof the model output maximum temperatures (into high 20's)ÌýlookÌýa tadÌýoptimistic; so we can shaveÌýa degree or twoÌýoff these and offer a likely TMax this afternoon around 25C.Ìý

Current forecast confidence for Friday's dry and settled themeÌýis high; high for Saturday's potential for mixed weatherÌýand highÌýfor Sunday's mostly dry conditionsÌýand small chance of showers.

AlongsideÌýhis manyÌýcredentials as a skilledÌýorator, the US President has now addedÌýa timely dose ofÌýweather wisdomÌýto his portfolio.

I wasÌýduly impressed.

YesterdayÌýafternoon (Monday) -ÌýinÌýtorrential rain and with lightning striking close by -ÌýBarack Obama attempted to start his speech, to huge crowds gathered at the in Elwood, Illinois, some 50 miles south of Chicago.

WithÌýa severe thunderstorm booming directly overhead; squally winds from the storm's downdraft tugged at the President's large umbrella. Standing at the lecturn, the PresidentÌýimmediately outlinedÌýa clear and present danger.

"We are a little bit concerned about lightning... this may not be safe," he told the thousands listening. "A little bit of rainÌýdoesn't hurt anybody,Ìýbut we don't want anybody being struck by lightning."Ìý

Urging everyone to return toÌýtheir cars (and they're ), he was absoluely right to call proceedings to a halt.

In such circumstances, crowds standing close togetherÌýin an open, exposed location, in wet clothes, is a recipe for lightning injury or fatality.ÌýIn previous similar circumstances, multiple casualties have occurred simultaneously - , affecting bothÌýplayers and spectactors alike. As well as direct cloud-to-ground strikes to humans, lightning canÌýside-flash off stadium structures, trees and such-like to injure or killÌýpeople. Closer to home, we've seen some decidedly hazardous conditions from , for example.

Lightning is a major weather perilÌýacross the USA, something President Obama will have been acutely aware ofÌýas he called-off his speech. In fact, there's a .

Indeed, in most years it causes more deaths thereÌýthan hurricanes or tornados: typically, some 60 people are killed across theÌýnation each year, with some 600 injured. Florida sees the highest number of casualties and in an average lifetime of 80 years, a US citizen has an estimated 1/6250 chance of being hit by lightning. However, only 10% of those struck are killed: 90% survive, .

Back here in the UK, we're entering the period when thunderstorms tend to become most prevalent, as the transitional and often very variableÌýphase of cooler toÌýwarmer conditions experiencedÌýin May leads (we hope!)Ìýinto summer.Ìý

I'm concerned at the lack of lightning-savvy, reckless or extremely foolhardyÌýbehaviour sometimes seenÌýin our country as threatening weather looms. For example, people continuing to shelter beneath trees during electrical storms; or insisting on playing aÌýfinal round on a golf course; or continuing aÌýhill-walking excursionÌýtowards a rain-lashed peakÌýas thunder rumbles all around. In a later blog this summer, I'll expand on some of these safetyÌýissues and examine the statistics nationally for lightning-related deaths and injuries.

Meantime, in my 91Èȱ¬ forecasts here,ÌýI am always at pains to highlightÌýany threat of thunderstorms. However, I always talk of the "risk of lightning", rather than the "risk of thunder" I hearÌýmentionedÌýin some forecasts.

Yes, there have been some injuries and fatalities caused by thunder in the direct senseÌý(e.g., riders suddenly dismounted by startled horses), but lightning is the potent threat (then resulting inÌýthe thunder), not the other way around!

I've seen first-hand,Ìýwhile working with back in the 1990's, just how devastating lightning can be to people and property. I've witnessed major property fires resulting from it; house roofs virtually blown to smithereens; an entire herd of cattle killed overnightÌýand on one occasion, we even had two of ourÌýfirefighters struck.

They were hit simultaneously as they worked to extinguish a rooftop fire on a house north of Watford andÌýwere extremely fortunate to avoid major injury. Oh - and the cause of the fire they were tackling?ÌýA lightning strike, justÌýa short time earlier...so much for "lightning never strikes twice", just one element inÌý!

Have you ever experienced lightning strikes to your home, or even to you, your familyÌýor friends? I'd be fascinated to hear your stories in the blog comments section below.

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