91Èȱ¬

Monaco, 13-16 May 2010 (Round 6)

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

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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

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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.