Archives for May 2010

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

(This forecast will be regularly updated. This entry: Sunday 30 May, 14:20hrs BST)

Quick Links:

• BBC Sport: Formula One
• BBC Weather: Turkey Forecast
• Local Rainfall Radar (via Turkish State Meteorological Service)
• Visible Satellite Loop (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: https://twitpic.com/1sf5u8

Sunday, 10:00hrs BST: Very warm, dry conditions this morning across the circuit and the original forecast for today continues to hold firm with little amendment. Increasing amounts of high cirrus cloud will become evident from the west through 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, for my 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 ambient most afternoons); generally a lot of strong sunshine and a very, very small risk of any showers, despite the periodically thundery conditions reliably forecast out across parts of the Balkans, Greece and some parts of eastern Turkey.

The model agreement keeps this threat firmly over in the European side of the Bosphorus / Sea of Marmara and - on the Asiatic side - a long way eastwards of Istanbul, too.

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

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

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Current Forecast Headlines:

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

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

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

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

After the rather cool conditions experienced at various races this year - most notably in China - it'll prove a very different challenge this time, as the teams take to architect Hermann Tilke's sweeping, undulating and much-praised circuit, which hosted it's inaugural Grand Prix in 2005. It's one of four anticlockwise races being held during this 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 2010 since Bahrain.

I've been keeping across some to-and-fro over the last 3 days in 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 / thundery conditions will be affecting parts of Greece and the Balkans during the race weekend; similarly, there's fairly consistent signal for showers (possibly thundery) at times further eastwards across Turkey. However, the current crop of model ensembles indicate that these are very unlikely around the circuit itself, so there's a high likelihood of dry running throughout each session.

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

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

For ever. From now.

But now that I have your attention, it's well worth a look at the satellite images I've added below. A glorious early summer weekend, as seen in true colour from space. The imagery is courtesy of Modis Rapid Response / NASA.

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

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

The second photo illustrates the slightly different story for a number of coastal areas yesterday (Saturday). Note the sea fog draped along England's North Sea coasts (and some nifty lee waves into parts of Kent, too). This all largely cleared later during the day across much of Norfolk, Essex, Suffolk and 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, subsiding atmospheric conditions, much of the nation remains cloud-free.

Monday's weather looks equally very warm (possible warmer still) for 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 - and hopefully with a fair amount of sunny spells, adding to the 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. Studies have linked this to a wider decrease in biodiversity and not least in our wild flowers and for that matter, across continental Europe, too.

To emphasise their plight and help make some amends, the BBC is a partner - alongside the National Trust - in a novel project started this week and running through the summer.

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

And for my part?

Alongside mentioning all this on BBC Points West 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 so uniquely British about spending a warm summer afternoon nestled in the garden (but not missing a Grand Prix in my case, obviously), beneath the ever-changing montage of fair-weather Cumulus clouds, listening to the harmless buzz of our ever-industrious bees.

Please do what you can to help this continue!

Monaco, 13-16 May 2010 (Round 6)

(This forecast will be regularly updated. This entry: Sunday 16 May, 12:50hrs BST)

Quick Links:

• BBC Sport: Formula One
• BBC Weather: Monaco Forecast

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Nowcast / Forecast updates:

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 nonethless it'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 prevail throughout 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 race remains consistently strong; still a 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 on Saturday morning, so can't update you weather-wise for FP3.... but hope to be doing so just ahead of qualifying, M4/M25/A1(M) traffic allowing! Hope you enjoy our coverage tomorrow, across all our platforms here on the BBC.

Friday, 12:00BST: The ensemble of 06z model runs are in broad agreement for Saturday's prospects, which reveal little significant variation from the forecast theme previously described: FP3 will be dry with sunny spells; qualifying also looks very 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 so on 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 output but overnight runs have continued to offer the same broad theme for Saturday. Mostly a dry signal, but important to note that all models offer a low - but consistently present - threat of showers into Saturday afternoon. So, a dry qualifying is a 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) at 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 cell can be seen at 2. Cumulus 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, MODIS Rapid Response).

Thurs. 20:00BST: With Saturday's free practice 3 and qualifying now just emerging into range of our higher-resolution NAE modelling, my previous forecast comments hold firm, with little significant change of emphasis. Saturday continues to look dry or mostly dry, with a continuing decline in the local rainfall signal with each successive model run. Sunny spells again expected through Saturday; dry for FP3 and very likely to remain dry during qualifying, albeit still retaining a low risk of showers. Low-level convergence and orographic influences will 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 influences below, under 'synoptic situation & forecast evolution'). So I assume the teams, through their own meteorological advice, are 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 of the storm cell we're tracking just west of circuit suggests it will pass just north of Monaco shortly....heavy downpours being recorded from it on radar.

Thurs, 13:05BST: Our high-resolution lightning detection system via the Met Office is recording a lot of lightning flashes now from 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: So far, so good with today's forecast. Showers now readily forming just inland across neighbouring coastal localities with precipitation from these cells fed ENE 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 https://www.meteoliguria.it/dati_osservati/areali/radar.html?type=rpa

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Current Forecast Headlines:

Thurs: Sunny spells; Max 18C. A few showers possible PM.

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

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

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It's back-to-back races this week and hot on the heels of departing Barcelona, we now turn our attention to Formula One's iconic, inimitable race at Monaco. 

Monaco's skyline is not guaranteed the dry, sunny conditions prevailing in this view, as the F1 event gets underway on Thursday against 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 circuits become rather emasculated, there's something very special about Monaco: 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 - with seeming aplomb.

And then there's the weather.

Chuck even a sprinkling of rain across the asphalt at La Rascasse, Casino Square or Loews Hairpin, and you're sure to stamp 'drama' onto every lap around this place. The very best in this sport have triumphed here in the wet; most - at some point - have also crashed in it, too. Inarguably, few races on the calendar prove so compelling from start to finish.

Once again, we're looking at another 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 local forecast emphasis.

Synoptic situation & forecast evolution:

The one certainty, weather-wise, is 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 ridge sitting north-south in the Atlantic will once again provide an effective blocked pattern, while an upper trough, dangling all the way out of Iceland down to southern Europe, will dictate the weather across 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 it has evolved into a very dominant feature, migrating northwards into 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 spread across many parts of southern France, northern Italy, Switzerland and environs through to the weekend, including - periodically, at least - across Monaco itself. My colleague Sarah Holt's hastily-snapped photo taken en-route to Monaco says it all!

During Thursday, the dominating upper trough sits all the way from the Arctic down across the British Isles, western Europe to the Western Mediterranean. On Saturday, an upper vortex forms above the northern Adriatic, coupled to a quite vigorous surface low that will drift across the northern Balkans towards the Black Sea into Sunday. It'll provide further emphasis for unsettled weather across southern France and northern Italy at times into the weekend. There's a strong inter-model signal for pressure rising slowly from the west into Sunday, which should steadily supress the risk of showers into the afternoon to potentially offer a dry race throughout. However, with a surface low never far away to the east, at this juncture it's impossible to reliably call the the race prospects for this event as wholly dry.

One regional feature that will probably become evident into the weekend, with the surface low evolving above northern Italy, is the northwesterly Mistral and northerly Tramontane 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 materialises across the principality on Thursday and Saturday especially.

As the flow spills down off the high ground encircled behind Monaco, it tends to undergo some degree of Foehn effect (adiabatic) warming, 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 orographically over the same high ground, condensing-out to offer - with convergence assistance too - towering cumulus clouds and an attendant shower risk a short distance inland. The coastal fringe and circuit, meanwhile, can 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 localised effects 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 action on Friday here!) could prove the first test in terms of how the local weather behaves, or not, for this year's event. Forecast modelling for 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 trough sitting effectively SW-NE across southern France (see latest Met Office synoptic chart, below), there's a potential for some showers at times. A sunny morning expected; free practice 1 will almost certainly stay dry. There's a growing, but still fairly low risk of showers affecting free practice 2; ambient temperature will reach 17-18C. Quite a breezy day at times - especially down at the marina and seafront - with 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) at 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. Modelling continues to suggest a dry session for free practice 3; a fair chance of a dry qualifying too, but a low chance (increasingly so, in most model runs) of some showers into the afternoon.

Forecast continuity has reasonably consistent for Saturday afternoon, indicative of light to moderate showers developing in districts from Nice eastwards to Liguria. Crucially however, the modelled signal for rain is significantly higher further inland rather than coastally and also eastwards of Monaco. By Friday we'll see how the higher-resolution models support these prospects. Winds will be lighter than Thursday; predominantly from the SW; with ambient temperature 16-17C. The teams will be keenly watching Saturday's forecast developments, not least given the concerns about qualifying for this event, already expressed by some team principals and drivers. Clearly, rain is by no means a certainty at this juncture, but to quote our Met Office Duty Forecaster at BBC Weather Centre, in a conversation with me on Tuesday:

"It would be worthy of a major pay rise if any F1 team employee guarantees, at this stage, a dry day throughout all of Saturday... and duly delivers the goods". 

The UK Met Office's synoptic chart for 12:00 GMT on Saturday calls for low pressure easing eastwards into the Balkans and a chance of showers forming through 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 on pressure building from the west, are broadly indicating improved conditions. Bar a generally small chance of showers still evident in some modelling, all forecasts lean heavily towards a dry event. Hazy bright or sunny spells across the principality; an ambient temperature around 17-18C and a mostly light southerly breeze.

Quite a few people have asked me today how our weather will fare as the country votes tomorrow (Thursday) in the General Election - 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 Norfolk, Suffolk, Kent and Sussex. Similar conditions will start to appear through the morning further north up the east coast, for example into Lincolnshire. London and the Home 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 fairly mild in 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 weather through the morning and into the afternoon, as 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 Newcastle) but more especially into a swathe confined south of the Mersey and westwards of Reading to Southampton, including the West Midlands, much of Wales and the West Country / South West.

By the afternoon, there will be a gradual improvement in many of these districts with brighter spells starting to emerge from the east, but also the chance of some slow-moving heavy - perhaps thundery - showers developing across the West Country into the mid and late afternoon. In the likes of Bristol 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 Cardiff, where the thermometer will show 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. Indeed the warmest conditions in the UK tomorrow are likely in and around Glasgow for example, where it should also become a good deal brighter during 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 of some early patchy drizzle and a few isolated light showers towards midday, it's a largely dry outlook here with a top temperature in Belfast of 13C.

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

Barcelona, 7-9 May 2010 (Round 5)

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

Quick Links:

• BBC Sport: Formula One
• BBC Weather: Barcelona Forecast

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

Sunday: The last two forecast updates I added (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 this morning's rainfall radar 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, with the rainfall pattern across much of Spain showing the clear effects of being influenced by orography (high ground). Latest radar shows a couple of small-scale convective developments south of Barcelona, being fed northwards off the sea; a chance of some isolated light showers around Montmelo this afternoon cannot be dismissed, but is a low likelihood.

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

The satellite imagery, meanwhile, shows an extensive veil of high cirrus and cirrostratus above Barcelona as it sits in the warm sector, with much of the earlier lower-level cloud cover now 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, given sufficient sunshine).

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Saturday: How 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 so into northern Spain and across above southern France. The Met Office has reliable aviation reports of fairly significant ash above the Pyrenees during Saturday and 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 heaviest of this wet weather tomorrow will afffect districts to the north / northwest of the circuit. The latest higher-resolution modelling leans (marginally) towards 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: No change to the qualifying forecast - looks dry, with sunny spells and ambient temperature around 19-20C; a very outside chance of isolated showers later, but mostly well west of the circuit. Incidentally, tomorrow's developments are very evident across Portugal in the current high-resolution satellite images.

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 west of Catalonia by race start, but most of the forcing (and attendant shower risk) is likely to affect areas west and northwest of Barcelona. Still a likelihood of light to moderate showers later in the 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. A small chance of showers.

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

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So, here's a teaser for all you pub quiz types and fact-collecting geeks: When was the last time an F1 season saw four out of the first five race weekends affected, at some stage, by rain?

I haven't even started to research the answer, but I'm sure someone with an encyclopaedic knowledge of the sport will promptly tell us the answer!? Please do share it, in the comments section below this blog... thanks!

Why am I asking? Because for the fourth time this season, the forecast prospects for the next round - at Spain's Circuit de Catalunya - also include a periodic chance of wet weather, including on race day itself.

Dry weather prevailed as Lewis Hamilton took 2nd place at the Circuit de Catalunya on 13 May 2007 (above); it was a similarly dry story for the race weekends in 2008 and 2009. But will wet weather add any extra spice in 2010? (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 prolonged dry conditions. The broad early expectations are for:

• Friday: Mostly cloudy at first but some brighter spells developing; comparatively cool nonetheless, with an ambient temperature around 15-17C. On balance, dry conditions are expected for both practice sessions with only a low chance of showers.
• Saturday: Brighter conditions expected, with temperatures around 18-19C accompanied by sunny spells. A small risk of scattered showers later, however.
• Sunday: Reasonable inter-model continuity as of the 12z output today (Sat) continues to offer the likelihood of light to moderate rain / showers starting to affect NE Spain during the late morning and afternoon, as per previous forecast updates. The latest prognosis from the various models we use (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 moderate showers / rain easing towards Barcelona and environs as the race is underway. Worth noting, however, how some recent model runs (including at 12z Saturday) have been a tad more more bullish, offering an earlier eastward spread of precipitation to influence the race from the outset.

Synoptic situation:
High pressure will remain in-situ west of the British Isles over the Atlantic for much of this week, keeping our own weather locked into an unseasonably cool northerly to northeasterly flow whilst also maintaining a blocked pattern of similarly cool weather for much of northwestern Europe.

The polar jetstream winds aloft will loop down southwards east of the Azores, while a large upper vortex grows to dominate east of Spain and yield a low pressure centre across the Western Mediterranean and southern France. This combination will help serve-up some distinctly inclement weather across parts of the NW Mediterranean - including Catalunya and the Balearics - especially between now and midweek. 

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 - and across northern Spain, offering some spells of rain and showers into the Pyrenees and Catalunya during the late afternoon and evening but unlikely to arrive while the practice sessions are underway. It'll be rather cool. Indeed into the weekend 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 Portugal during Sunday. Throughout the day, it will migrate eastwards across northern Spain, bringing the potential for outbreaks of rain into Barcelona and environs during the afternoon - but will its arrival coincide with the race itself?

Into the weekend, a slack southerly feed of warmer, moister air will tend to flow up across the Catalan Sea and Costa Brava, whilst cooler air remains aloft over northern Spain. By Saturday, the previously all-dominant surface low (and upper vortex) over Western Europe will be circulating above southern Bay of Biscay and withdrawing as a much weaker but still influential entity, with some troughs arcing away east from it to provide a chance of some showers into Catalunya. These will obviously prove a hit-and-miss affair and could have a small probability bearing on the qualifying session. On statistical balance however, it's likely to remain dry.

But the key change then comes into Sunday. By then, the jetstream - now positioned further north into the Bay of Biscay - ensures mobility in the Iberian weather is resumed from the West. It will steer an area of low pressure in off the Atlantic, across Portugal and mainland Spain. It'll then track eastwards / east-northeastwards, bringing wet weather to much of Iberia in the process. A rather cloudy warm sector will sit above Barcelona by race start, which is likely to be dry. Later in the afternoon, troughs will pep-up the shower threat ahead of an advancing cold front. However, most of these will 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 rain appearing 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 local rainfall radar can be seen here, with an alternative also available here. Take your pick!

More will follow in my further updates...