91Èȱ¬

Istanbul Park, 28-30 May 2010 (Round 7)

(This forecast will be regularly updated. This entry: SundayÌý30 May, 14:20hrs BST)

Quick Links:

• (via Turkish State Meteorological Service)
• (EUMETSAT, via sat24.com)

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Forecast / Nowcast updates:

Sunday, 14:20BST: If you are wondering why the shower seems so lame, refer to my remark before this race, in the comments below: "...the conditions will tend to favour any light showers largely evaporating before reaching the ground."

Sunday, 13:32hrs BST: Re my comment below about the small risk of showers.... well, we're watching a shower forming south of the circuit in a convergence zone; will this one shower hit the circuit? Looks possible!

Sunday, 10:25hrs BST: Current conditions at the circuit, as photographed by my colleague Sarah Holt:

Sunday, 10:00hrs BST: Very warm, dry conditions this morning across the circuit and the original forecast for todayÌýcontinues to hold firm with little amendment. Increasing amounts of high cirrus cloud will become evident from the westÌýthrough the afternoon, making the sunshine somewhat hazier with time. There's continuing inter-model agreement for the risk of showers to remain extremely low and ambient temperature to reach around 28C. A moderate breeze developing (much like on Saturday), predominantly northerly.

Thursday, 20:50hrs BST: No significant changes to add to the forecast I posted earlier this week. Well, that makes a change, forÌýmy F1 weather blogs this season!

Inter- (and intra) forecast model continuity has been pretty good for the best part of a week, since I wrote the initial entry.

We're set for fairly hot conditions (approaching or even exceeding 30C ambientÌýmost afternoons); generally a lot of strong sunshine and a very, ±¹±ð°ù²âÌýsmall risk of any showers, despite the periodically thundery conditions reliably forecast out acrossÌýparts of theÌýBalkans, GreeceÌýand some parts of eastern Turkey.

The model agreement keeps this threat firmly over inÌýthe European side of the Bosphorus / Sea of MarmaraÌýand - on the Asiatic side -Ìýa longÌýway eastwards of Istanbul, too.

As earlier noted, worth keeping an eye on the track temperatures through the practice sessionsÌýand consequent evidence of tyre degradation... could be a real factor, in my view.

Hope you enjoy our 91Èȱ¬ Red Button and Online coverage tomorrow (Friday)Ìýmorning, for FP1 from 07:55hrs local time!

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Current Forecast Headlines:

Friday:ÌýSunny and dry;Ìý Max 30C. Winds light, N.

Saturday: Sunny spells; variable cloud coverÌýand dry; Max 30C. Winds light, NE.

Sunday: Sunny and dry; Max 28C. Winds light-moderate, N-NE.Ìý

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Dry and fairly hot conditions look set to dominate the weatherÌýthroughout this next event at the Istanbul Park Circuit, located just southeast of the Turkish capital.

After the rather cool conditions experiencedÌýat various races this year -Ìýmost notablyÌýin China - it'll prove a very different challenge this time, as the teams take to architect Hermann Tilke's , which hosted it's inaugural Grand Prix in 2005. It's one of four anticlockwiseÌýracesÌýbeing held duringÌýthis year's race calendar (check out the video sequence, below).

Ambient temperatures here in Pendik, Akfirat County, will climb into the high twenties celsius each day; potentially reaching 30C at times on Friday and Saturday. With strong sunshine and generally well-broken cloud, the track temperature will soar to the highest values we've seen at any race weekend in 2010Ìýsince Bahrain.

I've beenÌýkeeping acrossÌýsome to-and-fro over the last 3 daysÌýin the broadscale synoptic developments, but the various forecast models we employ are now settling into general agreement, with a strong probability of dry weather prevailing.

Unsettled, showery / thunderyÌýconditions will be affecting parts of Greece and the Balkans during the race weekend; similarly, there'sÌýfairly consistent signal for showers (possibly thundery)Ìýat times further eastwards across Turkey. However, the current crop of model ensembles indicate thatÌýthese are very unlikely around the circuit itself, so there's a high likelihood ofÌýdry running throughout each session.

Further forecast detail (and any change to the emphasis) will follow here on the blogÌýas we approach Friday.

Ìý

Oh yes, make no mistake: I hate the term 'scorchio' and implore for it toÌýbe banned from all weather forecasts.

For ever. From now.

But now thatÌýI have your attention, it's well worth a look at the satellite images I've addedÌýbelow. A glorious early summer weekend, as seen in true colour from space. The imagery is courtesy of .

The firstÌýwas taken during the early afternoonÌýtoday (Sunday), with unbroken skies above all of southern and central England, as high pressure sits overhead, surpressing the cloud development. Glorious stuff.

Ìý No wonder temperatures have reached 26C+, in the strong sunshine.

The second photoÌýillustratesÌýthe slightly different story for a number of coastal areas yesterdayÌý(Saturday). Note the sea fog draped along England's North Sea coasts (and some nifty lee waves into parts of Kent, too). This allÌýlargely cleared laterÌýduring the day across much of Norfolk, Essex, SuffolkÌýand elsewhere. However, it remained stubbornly glued to some French coasts all day, formed in the slack easterly drift across cool (10-11C) sea surface temperatures. Note the airliner contrail clearly visible heading ENE out of Dartmoor.

In both photos, the influence of high ground is very evident, as convective clouds build in the flow, forced upwards downwind of the Pennines, Snowdonia and some other upland areas. But without this conspicuous orographic effect to push some clouds skywards against the dominating influence of stable, subsidingÌýatmosphericÌýconditions, much of the nation remains cloud-free.

Monday's weather looks equally very warm (possible warmer still)Ìýfor most southern districts, before we see a transition back towards seasonal average temperatures towards mid-week.

Oh yes - it's true.

After a decidedly cool period through most of May to-date, we're now locked into a distinct warming trend for the rest of this week, culminating in temperatures lifting towards the mid-20's C by Saturday.

It's looking like the warmest day of the year so far for many districts by then; likely to remain dry - at least for most, bar an isolated shower or two -Ìýand hopefully with a fair amount of sunny spells, adding toÌýthe quasi-Mediterranean feel.

One beneficiary of the warmer weather will be our native bee population. There's over 200 species in the British Isles, most of them solitary in nature, but all of them tend to share a worrying decline in abundance. and not least in ourÌýwild flowers and for that matter, across continental Europe, too.

To emphasise their plight and help make some amends, the 91Èȱ¬ is a partner - alongside the -Ìýin a novel project started this week and running through the summer.

'Bee Part of It', the strapline says...Ìýand I'd encourage you to have a look at our 91Èȱ¬ Breathing Places website for extra details.

And for my part?

Alongside mentioning all this on weather this evening, I bought a dozen packets of varied wildflower seeds from a local supermarket chain and will duly sow the whole lot across our front and back gardens in the coming days.

There's something soÌýuniquely British about spending a warm summer afternoon nestledÌýin the garden (but not missing a Grand Prix in my case, obviously), beneath the ever-changing montage of fair-weather Cumulus clouds,Ìýlistening to the harmlessÌýbuzz of our ever-industrious bees.

Please do what you can to helpÌýthisÌýcontinue!

Ìý

Ìý

Monaco, 13-16 May 2010 (Round 6)

(This forecast will be regularly updated. This entry: SundayÌý16 May, 12:50hrs BST)

Quick Links:

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Nowcast / ForecastÌýupdates:

Sunday, 12.55BST: A few showers now forming close to the Italian border and across the high ground north of Monaco, being fed southwards in the prevailing flow. So, the small risk of showers remains valid, but nonethlessÌýit's odds-on to remain a dry event, as forecast.

Saturday, 09:50BST: Good morning - a brief update for you all! The risk of any showers today remains very low and so we can assume dry running should prevailÌýthroughout today; hazy sunny spells with some high cirrus cloud aloft; temperatures rising to around 20-22C by this afternoon. The dry signal for tomorrow's raceÌýremainsÌýconsistently strong; stillÌýa small risk of an afternoon shower in the vicinity.

Friday, 22:30BST: Similar story to the last model output. Some minor inter-run variations as expected in this sort of set-up, but the broad theme remains as previously noted. I'm still not prepared to be bullish about the prospects for an entirely shower-free qualifying. Yes, it's certainly odds-on to remain dry, but I stress again how a shower signal in our higher resolution models remains fairly consistent, albeit a low % threat and far more likely to affect inland districts. The teams will surely remain a tad wary of this potential as they consider their strategy for the three sessions.

I'm off to Hertfordshire onÌýSaturday morning, so can't update youÌý weather-wiseÌýfor FP3.... but hope to be doing so just ahead of qualifying, M4/M25/A1(M) traffic allowing!Ìý Hope you enjoy our coverage tomorrow,Ìýacross all our platforms here on the 91Èȱ¬.

Friday, 12:00BST: The ensemble ofÌý06z model runs are in broad agreement for Saturday's prospects, which reveal little significant variation from the forecast theme previously described:Ìý FP3 will be dry with sunny spells; qualifying also looksÌývery likely to remain dry, again with pleasant sunny spells & variable cloud cover, with just a low chance of disruption from showers. Into the afternoon, these are expected to affect various districts just inland from the principality, but less soÌýon the coastal margin. Ambient temperatures will reach 18C by 1pm local time; winds at street level will be light and mostly southerly, but with a dominant cold northerly flow up aloft. Race day also looks likely to remain dry albeit again with a generally low threat of afternoon showers.

Friday, 05:00BST: I'm just awaiting the new ensemble of model outputÌýbut overnight runs haveÌýcontinued to offer the same broad theme for Saturday. Mostly a dry signal, but important to note that all models offer a low -Ìýbut consistently present -Ìýthreat of showers into Saturday afternoon. So, a dry qualifying isÌýa more likely outcome, but by no means guaranteed. Variable cloud cover through the day, as earlier noted.

This vibrant satellite image, taken yesterday during free practice 2, shows some interesting weather aspects around southern France and Monaco (red dot)Ìýat the time. At 1, a large cumulonimbus cell was delivering thundery downpours into Nice; it's conspicuous anvil aloft swept northeastwards in the prevailing upper winds. This cell delivered some rain across Monaco towards the end of FP2. A smaller storm cellÌýcan be seenÌýat 2.ÌýÌýCumulus streets are clearly visible in the brisk northwesterly flow at 3 through the Rhone valley, where the cool, dry Mistral winds have cleared much of the cloud cover. At 4, distinctive rope clouds arc across the Ligurian Sea, with low pressure sitting not far eastwards delivering a number of showers across northern Italy. (Image: Courtesy NASA/GSFC, ).

Thurs. 20:00BST: With Saturday's free practice 3 and qualifying now just emerging into range of our higher-resolution NAE modelling,Ìýmy previous forecast commentsÌýhold firm, with little significant change of emphasis. Saturday continues to look dry or mostly dry, withÌýa continuing decline in the local rainfall signal with each successive model run. Sunny spells againÌýexpectedÌýthrough Saturday; dry for FP3 and very likely to remain dry during qualifying, albeit still retainingÌýa low risk of showers. Low-level convergence and orographic influencesÌýwill tend to build cloud slightly inland. This, combined with the drier N-NE flow slightly aloft, will help keep a good deal of sunnier weather along the coastal fringe of the Côte d'Azur (refer to my earlier comments on regional influencesÌýbelow, under 'synoptic situation & forecast evolution'). So I assumeÌýthe teams,Ìýthrough their own meteorological advice,Ìýare also leaning towards a dry qualifying session (or at least hoping so!).

Thurs 13:46 BST: I'll be amazed if the circuit manages to dodge this storm cell... it does look highly likely to give rain there in the next 10 mins or so.

Thurs, 13:35BST: Trajectory ofÌýthe storm cell we're tracking just west of circuit suggests it will pass just north ofÌýMonaco shortly....heavy downpours being recordedÌýfrom it on radar.

Thurs, 13:05BST: Our high-resolution lightning detection system via the Met Office is recording a lot of lightning flashes nowÌýfrom a storm cell just west of Monaco.... if it (or other similarly lively cells) crosses the circuit, which is quite possible, it will give a real downpour.

Thurs, 12:20BST:ÌýSo far, so good with today's forecast. Showers now readily forming just inland across neighbouring coastal localities with precipitation from these cells fedÌýENE in the prevailing flow. These are being formed with influences of local orography. Certainly not impossible to see some affecting the circuit for free practice 2; albeit most will preferentially form slightly further inland above and upstream of the higher ground. Local rainfall radar available at

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Current Forecast Headlines:

Thurs:ÌýSunny spells;Ìý Max 18C. A few showersÌýpossible PM.

Sat: Variable cloud cover &Ìýsunny spells; Max 21C.ÌýA few showers possible PM.

Sun: Sunny spells;ÌýMax 21C. Light winds. Dry race expected.

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It's back-to-back races this week and hot on the heels ofÌýdeparting Barcelona, we now turn our attention to Formula One's iconic, inimitableÌýrace at Monaco.Ìý

Monaco's skyline is not guaranteed the dry, sunny conditions prevailing in this view, as the F1 event gets underway on ThursdayÌýagainst a backdrop of unsettled weather across the region.

I absolutely love this event and I'm sure many (most?) of you share my view. As so many other historic circuitsÌýbecome rather emasculated, there's something very special aboutÌýMonaco: the unashamed opulence and vibrancy; those tiny margins of error between utterly unforgiving barriers; the sheer brilliance of those who can throw an F1 car around this extraordinary place - lap after lap, in metronomic fashion -Ìýwith seeming aplomb.

And then there's the weather.

Chuck even a sprinkling of rain across the asphalt atÌýLa Rascasse, Casino Square or Loews Hairpin, and you're sure to stamp 'drama' onto every lap around this place. The very best in this sportÌýhaveÌýtriumphed here in the wet;Ìýmost - at some point -ÌýhaveÌýalso crashed in it, too.ÌýInarguably, few races on the calendar prove soÌýcompelling from start to finish.

Once again,Ìýwe're looking atÌýanother weather story worth following right to the chequered flag: because with all our forecast models indicating further unsettled weather across much of the western Mediterranean and mainland Europe between now and race day, I have little doubt we're into another journey of a changeable localÌýforecast emphasis.

Synoptic situation & forecast evolution:

The one certainty, weather-wise,Ìýis that the Azores high will dominate out in the North Atlantic and low pressure likewise across central Europe and the Northern Mediterranean.

A substantial upper ridgeÌýsitting north-south in the AtlanticÌýwill once again provide an effectiveÌýblocked pattern, while an upper trough,Ìýdangling all the way out ofÌýIceland down to southern Europe,Ìýwill dictate the weatherÌýacross much of continental Europe and continue to offer unseasonably cool conditions for many.

Rather continuing a theme we saw emerging ahead of the Spanish GP, a surface low pressure system has established this week in the western Mediterranean, from where itÌýhas evolved intoÌýa very dominant feature, migratingÌýnorthwardsÌýinto eastern-central Europe. With attendant fronts and troughs feeding-down in the northerly flow, bouts of wet (and in some places, very wet and thundery) weather will spreadÌýacross manyÌýparts of southern France, northern Italy, SwitzerlandÌýand environsÌýthrough toÌýthe weekend, including - periodically, at leastÌý- across Monaco itself.Ìý My colleague Sarah Holt's says it all!

DuringÌýThursday, theÌýdominatingÌýupper trough sits all the way from the Arctic down across the British Isles, westernÌýEurope to the Western Mediterranean. On Saturday, an upper vortexÌýforms above the northernÌýAdriatic, coupled to a quite vigorous surface low that will driftÌýacross the northern Balkans towards the Black SeaÌýinto Sunday. It'll provide further emphasis for unsettled weather acrossÌýsouthern France and northern ItalyÌýat times into the weekend.ÌýThere's aÌýstrong inter-model signal forÌýpressure rising slowly from the west into Sunday, which shouldÌýsteadilyÌýsupress the risk of showersÌýinto the afternoon to potentially offer a dry race throughout. However, withÌýa surface low never far away to the east,Ìýat this juncture it'sÌýimpossible to reliably call the the race prospectsÌýfor this event as wholly dry.

One regional feature that will probably become evident into the weekend, withÌýthe surface low evolving above northern Italy,Ìýis the northwesterly and northerly winds blowing down across Provence and also into the Côte d'Azur. Cold air is fed down off the Alps towards Monaco, but there's some important localised factors at work that will very much dictate how the weather materialisesÌýacross the principality on Thursday and Saturday especially.

As the flowÌýspills down off the high ground encircled behind Monaco, it tends to undergo some degree ofÌý (adiabatic)Ìýwarming, helping clear the skies coastally. At the same time, and probably more importantly for this race event, a southerly low-level breeze off the Mediterranean is forced up orographicallyÌýover the same high ground, condensing-out to offer - with convergence assistance too -Ìýtowering cumulusÌýclouds and an attendant shower risk a short distance inland. The coastal fringe and circuit, meanwhile,Ìýcan stay brighter and dry, whilst the peaks north of Monaco remain draped in cloud. It's going to be interesting watching satellite and radar to see if this combination of localisedÌýeffects helps spare the track sessions from much of the showery wet weather... or not!

Session Forecasts

Thursday's practice sessions (remember: there's no track actionÌýon Friday here!) could prove the first test in terms of how the local weather behaves, or not, for this year's event. Forecast modellingÌýfor the day has shown pretty good continuity and it's now well into range of the Met Office's higher-resolution NAE model. With a troughÌýsitting effectively SW-NE across southern France (see latest Met Office synoptic chart, below),Ìýthere's a potential for some showers at times. AÌýsunny morning expected; free practice 1 will almost certainly stay dry. There's a growing, but still fairly low risk of showersÌýaffecting free practice 2; ambient temperature will reach 17-18C. Quite a breezy day at timesÌý- especially down at the marina and seafrontÌý-Ìýwith winds from the SW/SSW. Any rainfall accumulation from start of FP1 to end of FP2 unlikely to exceed 1-3mm.

The UK Met Office's latest synoptic chart for 12:00 GMT on Thursday shows a trough draped through northern Spain and across towards northern Italy, likely to deliver showers into Monaco (red dot)Ìýat times (Image: Courtesy UK Met Office)

Saturday's current forecast expectations, with low pressure centred out east across the Adriatic (see chart, below), are still impossible to localise with anything more than moderate confidence.ÌýModelling continues toÌýsuggest a dry session forÌýfree practice 3; a fair chance of a dry qualifying too, but a low chanceÌý(increasingly so, in most model runs) of someÌýshowers into the afternoon.Ìý

Forecast continuity has reasonably consistent for Saturday afternoon, indicative of light to moderate showers developing in districtsÌýfrom Nice eastwards to Liguria. Crucially however,ÌýtheÌýmodelled signal for rainÌýis significantlyÌýhigher further inland rather than coastally and also eastwards of Monaco. By FridayÌýwe'll see how the higher-resolution models supportÌýthese prospects. Winds will be lighter than Thursday; predominantly from the SW; with ambient temperature 16-17C. The teams will be keenlyÌýwatchingÌýSaturday's forecast developments, not least given the concerns about qualifying for this event,Ìýalready . Clearly, rain isÌýby noÌýmeansÌýa certainty at this juncture, but to quote our Met Office Duty Forecaster at 91Èȱ¬ Weather Centre, in a conversation withÌýmeÌýon Tuesday:

"It would beÌýworthy of a major pay riseÌýif anyÌýF1 team employee guarantees, at this stage,Ìýa dry dayÌýthroughout all of Saturday... and duly delivers the goods".Ìý

Ìý

Ìý The UK Met Office's synoptic chart for 12:00 GMT on SaturdayÌýcalls forÌýlow pressure easing eastwards into the Balkans and a chance of showers formingÌýthrough parts of southern France and northern Italy. It'll be a radar-watching story at Monaco that afternoon. (Image: Courtesy UK Met Office)

Sunday's race prospects, with all models agreeing onÌýpressure building from the west, are broadly indicatingÌýimproved conditions. BarÌýa generally small chance ofÌýshowers still evident in some modelling, all forecastsÌýlean heavilyÌýtowardsÌýa dry event. HazyÌýbright or sunny spells across the principality;Ìýan ambient temperature around 17-18C and a mostly light southerly breeze.

Quite a few people have asked me todayÌýhow our weather will fare - and it'll prove a day of mixed fortunes (I'm talking in the meteorological sense!)...

The southeastern quadrant of England will see the best of the day's weather, with dry, bright and sunny conditions prevailing across the likes of , Suffolk, Kent andÌýSussex. Similar conditions will start to appear through the morning further north up the east coast,Ìýfor example into Lincolnshire. and the 91Èȱ¬ Counties will start with a good deal of cloud, but tend to brighten-up towards midday and into the afternoon. All these areas should then remain dry throughout the day and it'll feel fairlyÌýmildÌýin the sheltered inland sunnier spots, as temperatures reach 13 to 15C.

Outside of these areas, it's a different scenario. Much of England and Wales will see a lot of cloud & some intermittent wet weatherÌýthrough the morning and into the afternoon,Ìýas patchy outbreaks of (mostly light) rain and showers affect many areas. These will tend to become focused with time, across parts of the North East (where we'll see a chilly 9C in )Ìýbut moreÌýespeciallyÌýintoÌýa swatheÌýconfined south ofÌýthe Mersey and westwards of Reading to , including the WestÌýMidlands,Ìýmuch of WalesÌýand the West Country / South West.Ìý

By the afternoon, there will be a gradual improvement in many of these districtsÌýwith brighter spells starting to emerge from the east, but also the chance of some slow-moving heavy -Ìýperhaps thundery -ÌýÌýshowers developing across the West Country into the mid and late afternoon. In the likes of and Bath, for sake of example, the risk of showers should fade by early evening and temperatures will have peaked around 13C. It's a similar story in , where the thermometer willÌýshow 14C.

Scotland will also see some mostly light and rather patchy outbreaks of rain at times through the morning and early afternoon, with the exception of many western districts of the Highlands, where drier conditions should prevail with pleasant sunny spells.ÌýIndeed the warmest conditions in the UK tomorrowÌýare likelyÌýin and around for example, where it should also become a good deal brighterÌýduring the afternoon - top temperatures here will reach around 16 to perhaps 17C.

Northern Ireland will also have a largely overcast start to the day, but with the exception ofÌýsome early patchy drizzle and aÌýfew isolated light showers towards midday, it's a largely dry outlook here with a top temperature in of 13C.

As the country awakes to the election results into Friday, it'll prove another rather cool prospect throughout the dayÌýwith variable amounts of cloud; sunny spells for some eastern districts especiallyÌýand a fairly broad scattering of showers elsewhere.

Barcelona, 7-9 May 2010 (Round 5)

(This forecast will be regularly updated. This entry: SundayÌý09 May, 09:50hrs BST)

Quick Links:

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Nowcast/Forecast Update, SUN - RACE; 09:50hrs:

Sunday: The last twoÌýforecast updates I addedÌý(below) re today noted how our higher-resolution Met Office modelling wanted to take the heaviest of the rain north-northwest of the circuit by a fair margin, up into the Pyrenees. Comparison of versus the latest (00z) model prediction strongly supports this outcome. The spells of rain have duly arrived and indeed passed well to the N-NW of the circuit,Ìýwith the rainfall pattern across much of SpainÌýshowing the clear effects of being influenced by orography (high ground).Ìý Latest radar shows a couple of small-scale convectiveÌýdevelopments south of Barcelona, being fed northwards off the sea; a chance of some isolated light showers around MontmeloÌýthis afternoon cannot be dismissed, but is a low likelihood.

So, the forecast emphasis I penned yesterdayÌý- i.e., "...leaning towards a drier rather than wetter outcome" -Ìýstill looks very likely, with the broad thrust remaining one of dry conditions, with aÌýlatent (low) chance of scattered light showers. The Spanish modelling still calls for a rain chance of 65% today,Ìýbut on balance,ÌýI'd call it closer to 30% or less.

The , meanwhile,Ìýshows an extensive veil of high cirrus and cirrostratusÌýabove Barcelona as it sits in theÌý, with muchÌýof the earlier lower-level cloud coverÌýnow readily fragmenting to offer brighter / hazy sunnier spells around the circuit. A milder southerly flow off the Catalan Sea will help today's temperatures reach around the expected 19-20C (perhaps a little more, givenÌýsufficient sunshine).

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Saturday:ÌýHow hard can this forecast get? Well, very (oh, and incidentally: early prognosis suggests a wet Monaco GP).

Firstly: Worth noting that the spectre of volcanic ash has returned and especially soÌýinto northern Spain and across above southern France. The Met Office has reliable aviation reports of fairly significant ash above the Pyrenees during SaturdayÌýand we might well see some further issues tomorrow. I do hope those of you travelling home from the race tomorrow aren't affected in the manner we witnessed after the Shanghai weekend.

So, onto the action at ground level. Sunday's latest prognosis continues to offer a chance of rain, but by no means a certainty. The heaviestÌýof this wet weatherÌýtomorrow will afffect districtsÌýto theÌýnorth / northwest of the circuit. The latest higher-resolution modelling leans (marginally)Ìýtowards a drier rather than wetter outcome, but with a threat of some (mostly light) showers or rain never too far away, possibly from the race outset.

Saturday:ÌýNo change to the qualifying forecast - looks dry, with sunny spells and ambient temperature around 19-20C; a very outside chanceÌýof isolated showers later,Ìýbut mostly well west of the circuit.ÌýIncidentally, tomorrow's developments are very evident across Portugal in the .

Saturday: Continued forecast confidence in a dry, sunny theme for FP3. Early this morning, a thundery trough departed northeastwards, having brought a band of showers through Barcelona and environs. There's a small chance of showers later today, but highly likely we'll continue with dry, partly sunny weather into qualifying. Ambient temp. around 19C.

Sunday: No significant change to previous forecast. UK Met Office predicts the cold front will sit not far westÌýof Catalonia by race start, but most of the forcing (and attendant shower risk)Ìýis likely to affect areas west and northwest of Barcelona. Still a likelihood of light to moderate showers later inÌýthe race however, so a dry event is by no means guaranteed.

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Forecast Headlines:

Friday, FP1 & 2: Likely to be dry. Small chance of showers.

Saturday, FP3 & Qualifying: Likely to be dry. AÌýsmall chance of showers.

Sunday, Race: Some mostly light showers / rainÌýpossible, especially later.

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So, here'sÌýa teaserÌýfor all you pub quiz types and fact-collecting geeks: When was the last time an F1 season sawÌýfour out of the first five race weekends affected, at some stage,Ìýby rain?

I haven't even started to research the answer, but I'mÌýsure someone with an encyclopaedicÌýknowledge ofÌýthe sportÌýwill promptly tellÌýus the answer!?ÌýPlease do share it, in the comments section below this blog... thanks!

Why am I asking? BecauseÌýfor the fourth time this season, ÌýtheÌýforecast prospects for the next round -Ìýat Spain's Circuit de Catalunya - alsoÌýinclude a periodic chance of wet weather,ÌýincludingÌýon race day itself.

Dry weather prevailed as Lewis Hamilton took 2nd place at the Circuit de CatalunyaÌýon 13ÌýMay 2007 (above); it was a similarly dry story for theÌýrace weekendsÌýin 2008 and 2009.ÌýBut will wet weather add any extra spice inÌý2010? (Photo: Bryn Lennon / Getty Images)

Forecast summary:
It's an unsettled weekend brewing across Iberia and at no stage of the race event is there a compelling signal for any prolongedÌýdry conditions. The broad earlyÌýexpectationsÌýare for:

• Friday:ÌýMostly cloudy at first butÌýsome brighterÌýspells developing;Ìýcomparatively cool nonetheless, with anÌýambient temperature around 15-17C.ÌýOn balance, dry conditions are expected for both practice sessions with only aÌýlow chance of showers.
• Saturday:ÌýBrighter conditions expected, with temperatures around 18-19C accompanied by sunny spells. AÌýsmall risk of scattered showers later,Ìýhowever.
• Sunday:ÌýReasonableÌýinter-model continuity as of the 12zÌýoutput today (Sat) continues to offerÌýthe likelihood of light to moderateÌýrain / showers starting to affectÌýNE SpainÌýduring the late morning and afternoon, as per previous forecast updates. The latest prognosis from the various models we useÌý(e.g., UK Met Office NAE and Global Model; ECMWF ensemble products; US-GFS; French Arpege; Canadian and German models) lean more towards a largely dry but increasingly cloudy morning; then a prospect of light to moderateÌýshowers / rainÌýeasing towardsÌýBarcelona and environs as the race is underway. Worth noting, however,Ìýhow some recent model runs (including at 12z Saturday)Ìýhave been a tad more more bullish, offering anÌýearlier eastward spread of precipitation to influence the race from the outset.

Synoptic situation:
High pressure will remain in-situÌýwest of the British Isles over the Atlantic for much of this week, keeping our own weather lockedÌýinto an unseasonablyÌýcool northerly to northeasterlyÌýflow whilstÌýalso maintaining a blocked pattern of similarly cool weatherÌýfor much of northwestern Europe.

The will loop down southwards east of the Azores, whileÌýa largeÌý grows to dominate east of SpainÌýand yield a low pressure centre across the Western Mediterranean and southern France. This combination will help serve-up some distinctlyÌýinclementÌýweatherÌýacross parts of the NW Mediterranean - including Catalunya andÌýthe Balearics - especially between now and midweek.Ìý

By Friday, the core remnants of the vortex will feed a small-scale low pressure centre eastwards out of southern Biscay - with a lot of moisture entrained in it -Ìýand across northern Spain, offering some spells of rain and showers into the Pyrenees and Catalunya during the late afternoon and eveningÌýbut unlikely to arrive while the practice sessions are underway. It'll be rather cool. Indeed into theÌýweekend of track action, ambient temperatures are unlikely to top 17 to 21C.

The Met Office's Global Model, above, shows an Atlantic depression centred just west of PortugalÌýduring Sunday.ÌýThroughout the day, it will migrate eastwards across northern Spain, bringingÌýthe potential for outbreaks of rainÌýinto Barcelona and environsÌýduring the afternoon - but will its arrival coincide with the race itself?

Into the weekend, aÌýslack southerly feedÌýof warmer, moisterÌýairÌýwill tend to flow up across the Catalan Sea and Costa Brava, whilstÌýcooler airÌýremainsÌýaloft over northern Spain. By Saturday,Ìýthe previously all-dominantÌýsurface low (and upper vortex)Ìýover Western Europe will beÌýcirculating above southern Bay of Biscay and withdrawingÌýas a much weakerÌýbut still influential entity, with some troughs arcing away east from it to provide a chance of some showers into Catalunya. TheseÌýwill obviously prove a hit-and-miss affair and couldÌýhave a small probabilityÌýbearingÌýon the qualifying session. On statistical balance however, it's likely to remain dry.

But the key change then comesÌýinto Sunday. By then, theÌýjetstream - now positioned further north into the Bay of BiscayÌý-Ìýensures mobility in the Iberian weather is resumed from the West. It will steer anÌýarea of low pressureÌýin off the Atlantic, across Portugal and mainland Spain. It'll then track eastwards / east-northeastwards,ÌýbringingÌýwet weather to much of Iberia in the process. A ratherÌýcloudy warm sectorÌýwill sit above Barcelona by race start, which is likely to be dry. Later in the afternoon, troughs willÌýpep-up the shower threat ahead ofÌýan advancingÌýcoldÌýfront. However, most of theseÌýwill affect areas slightly further north and west. So a reasonable chance of a dry race start, with a threat of light to moderate showers and rainÌýappearing later, seems the most probable outcome.

It'll be another radar-watching story if you want to keep up with the minute-by-minute weather prospects... the , with an alternative . Take your pick!

More willÌýfollow in my further updates...