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Hungaroring, 30 July - 01ÌýAugust 2010 (Round 12)

(This forecast will be regularly updated. This entry: SundayÌý1 August, 09:30hrs BST)

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Nowcast Updates: (NB - previous updates have been moved to the end of this blog)

SUN 09:25 BST: A glorious, cloudless morningÌýin Budapest with strong sunshine across the circuit and the track temperatures will be a good deal higher than yesterday. The fine, rather hot weather will prevail through today, albeit with some fair-weather cumulus around into this afternoon and only a very small (<10%) chance of any of this developing further locally, to offer well-isolated showers. Indeed, the precipitation signal from the ensembles today is effectively just trace amounts at Budapest (1mm or so). The upper trough that offered the more widespread showery / thundery weather of Friday and Saturday has relaxed off eastwards, where deep convection is now primarily focused across the high ground of western Romania this morning.

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SAT 13:45 BST: The showers now forming in a developmental areaÌýSE of the circuit will not arrive until after qualifying - by which timeÌýthey could be turning heavier and thundery.

SAT 11:55 BST: The steering upper flow at 750 / 500hPa is essentially NNW-N at present, hence directing the storms a smidgeÌýwest of Budapest in the next hour or so. It's thisÌýsort of fairly small-scale margin of forecast uncertainty that can make all the difference when trying to broad-brush a 'showery' forecast some hours / days ahead! As noted below, had this thundery cluster and downpoursÌýbeen 30-40 miles east (and that's really nothing in meteorological terms of forecast error bar), qualifying would be all set for some major (weather) drama...potentially even to the extent of being undriveable.ÌýOh well!

SAT 11:40 BST: I bet the teams (if not the fans)Ìýare breathing a sigh of relief that the thunderstorms are staying firmly on the west side of the Danube - had they been on the east side, with the same progress, spatial coverageÌýand northerly track, it wouldÌýhave beenÌýa direct hit for qualifying!

SAT 11:20 BST: No threat expectedÌýfor qualifying from the lively cluster of thundery cells continuing toÌýease NNW into southern/central Hungary - current trajectory of this featureÌýensures itÌýwill track slightlyÌýwest of Budapest later. So, aside from any isolated shower potential fromÌýlocal convective development (as temperatures rise to release instability), it's a dry, fine and increasingly very warmÌýstory continuing todayÌýinto qualifying.

SAT 09:44 BST: FineÌýconditions atÌýthe circuit for FP3 then; worth keeping an eye for later on the next cluster of heavy showers and thunderstorms just easing into south Hungary (now visible on radar).

SAT 09:00 BST: Hmmm. Some mid-level instability is rather noticeable in webcam shots above BudapestÌýduring theÌýlast 15 minutes. Will keep an eye on it....

SAT 08:30 BST: So, as forecast the rain was fairly extensive last night and pretty heavy in places, too. Thunderstorms rumbled not far south of the circuit until dawn; some high veils of cirrus this morning now the last visible evidence of them. The showers have now faded and sunshine prevails, with dry weather across northern Hungary. As noted in my forecasts earlier (see below), we can expect some extensive dry periods now, albeit with the chance of showers re-formingÌýlater. It's very possible these will appear post-qualifying however, so we can't rely on the weather gods to shake-up this particular grid! We shall see....

SAT 00:05 BST: The thundery rain forecast for tonight finally looms into view. In the next hour, some moderately heavy downpours will ease north across the circuit. Thundery elements are now widespread within the rainband, with a lot of recent lightning showing on the detection network (see link above). The latest UKMO NAE modelling continues the shower threat into the remainder of today, but - as noted all along - some prolonged drier intervals for many districts. So, the sessions could stay dry, but with showers building later PM.

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Forecast Summary:

(PPN = Precipitation)

Emphasis: Showers likelyÌýat times, but some prolonged dry and warm interludes dominating. Latest ensembles offer periodic wet weather arriving Friday (heaviest late PM); some spells of rain / showers Saturday - again mostly late PM; with Sunday largely dry & fine; a lowÌýchance of scattered showersÌýdeveloping PM.Ìý

Friday:ÌýMostly cloudy; some brighter / sunnyÌýspells at times through broken mid-level cloud.ÌýOutbreaks of rain / showers / thunderstormsÌýedging slowly east; these likely to develop more widely eastwardsÌýin theÌýafternoon / evening / overnight,Ìý turning prolonged & heavy in places. Chance of PPN 70% (PM). Max 22C. Wind variable; light SSE / SSW later.

Saturday: Variable cloud cover with thundery spells of rain possible very early AM. Sunny spells then developing, albeitÌýwith some extensive high cloud at times and turning cloudier into the afternoon. Prolonged dry spells, potentially lastingÌýfor both track sessions. Showers forming through the afternoon and into the evening across Budapest area, some heavy. Chance of PPNÌý50%.Ìý Max 25C. Wind lightÌýNNW.

³§³Ü²Ô»å²¹²â:ÌýWidespread sunshine. Very warm. Dry, fineÌýweather across northern Hungary; some limited convective cloud building locally through the afternoon to introduce a very low risk ofÌýwell-scattered showers, but more soÌýin eastern areas of Hungary. Dry race very likely. Chance ofÌýPPNÌý10%. Max 28C. Wind light WNW.Ìý

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Synopsis & Forecast Evolution:

(With sincere thanks to Mike Trigger, Deputy Chief Forecaster, UK Met Office, for his expertÌýinputÌýinto my preparation of this latest forecast update)

Located in Mogyoród, some 11 miles (18km)Ìýnortheast of Budapest, the Hungaroring circuit isÌýsetÌýin aÌý semi-rural topographical 'bowl' andÌýoften prone to bone-dry, dusty conditions at this time of year. However, it might be anything but dry and dusty at timesÌýlater during Friday and indeed Saturday too, asÌýan occludingÌýfront - tied to an upper trough -Ìýswings eastwards across Hungary through the weekend, offering a strong likelihood of showers making an appearance at various times around Budapest.

There'sÌýgrowing inter-model agreement for the broad evolution onÌýFriday, as the frontal system - sitting effectively quasi-stationary for much of the day through Austria, CroatiaÌýand western Hungary - slowly starts to edge a bit further east.

However, some small timing differences between the key models (ECMWF, UKMO-GM and US-GFS) are critical and account for some of the 'spot forecast' variation many of you might have read on different weather websites!

For most of Friday, the modelsÌýdo concurÌýin keeping the very wettest conditions further west / SW beneath the upper trough, especially across the borderlands with Austria and down into Slovenia andÌýCroatia.

FP1Ìýshould stayÌýdry albeit one or two showers are possible even at that stage of the day under largely brighter conditions. But as more cloud spills eastwards into the afternoon, it offersÌýaÌýsteadilyÌýincreasing chance of seeing some showers at times, associated with waves of upper forcing running northwards through the frontal band. The rate of frontal progression (and it has tended to vary!) will be important here for the wet/dry fortunes of FP2.

Thereafter, we expect an increasingÌýchance of some periodically wet (potentially very wet)Ìýweather arriving later into the afternoon, evening and overnight... it's possibleÌýsome of the downpours will turn heavy and thundery, offeringÌýaÌýstrong possibility of the circuit returning to entirely 'green' conditions ahead of Saturday.

Saturday will see the upper trough and occluding front moving further east across Budapest.ÌýThe day may start overcast with some early morning thundery rain; thereafter brighter spells developing and a dry window likely into FP3 and qualifying.

However, under sunny spells and aided by insolation, the clouds are likely to start building into the afternoon in the distinctlyÌýunstable conditions and later offer a likelihood of showers, potentially around the time of qualifying but more especially afterwards.Ìý

By Sunday the models all agree on the upper trough relaxing further awayÌýto the east, albeit with some slight differences on exactly how far east it sits.

It's expected for the race toÌýrun in the sort of entirely dry andÌývery warm conditions so often witnessed at this track, with strong sunshine. However, a few areas of convective cloud could bubble-upÌýinto the afternoon locally across some districts of Hungary, perhaps providing a (very low) chance of an isolated shower, but these are much more likely out further to the east.Ìý

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Previous Nowcast Updates...

FRI 12:30 BST: The next frontal wave running up out of Zagreb area (Croatia) into SW Hungary is turning very lively and producing some readily thundery embedded cellsÌýwith prodigious lightning. It'll track NNE into Budapest later for this evening. Meantime, as the current 'old' wave dies quickly now, the circuit should escape dry for FP2, bar a few spots of rain... not totally clear-cut given a bit of re-activation at the extreme south of this current plume of rain.

FRI 12:20 BST: A fair bit more rain on the webcam now, so at least there's some reliable groundtruth for tallying to the recorded rainfall radar return...!

FRI 12:10 BST: I suspect the teams are going to just get lucky here! The rain progress is (a) very slow eastwards and (b) rapidly now losing upper forcing in any case. I expect it might offer a few spots of rainÌýinto the circuit later in the session, but probably nothing more. So a good chance for FP2 to run under overcastÌýskies (so lower track temperature) but inÌýdry or largely dry conditions... meanwhile, as this area of rain fades northwards this afternoon, the next pulse is visible to the SSW on radar, being fed up as another wave runs up the frontal zone northwards. IIt'll offer a further threat of heavy showers / rain later this evening and tonight across Budapest.

FRI 12:00 BST: Spots of rain again now on the webcam in central Budapest...extensive high-based stratocumulus and altocumulus stratiformis above....

FRI 11:45 BST: Well, it's going to be interesting for FP2. You might recall how in the forecast text (below) I'd suggested: "The rate of frontal progression (and it has tended to vary!) will be important here for the wet/dry fortunes of FP2." No need to change this viewpoint... currently, it's raining on the western edge of Budapest but the eastward creep of the frontal band is very, very slow. Equally, the forcing is being gradually relaxed aloft, so trending more towards light / moderate rain for now. The increasing cloud and grey skiesÌýnow across Budapest (see webcam above)Ìýare testimony to the close proximity of rain... but it's seeminglyÌýfalling largely from mid-level instability close to the capital itself.

FRI 09:45 BST: The frontal rain lies not far west now of Budapest (see radar link above), with much of the earlier forcing now fading as we see a relaxing of the waves which will periodically run from south to north up the feature during today. This ebb and flow of development was well signalled in the latest models. For now, more widespread sunny spells prevailing; a hint of some localised convective development but any threat of showers held at bay through this session. By FP2 the frontal zone will be closer.

FRI 08:10 BST: Some hints of brighter / sunnierÌýspells as the mid-level (altocumulus / altostatus) cloud breaks at times. The main rain and shower threat continues to be held out west, as per expectations. A reasonable chance for dry running in FP1 then, but further showers developing not far SSW of Budapest... and thundery oubreaks now in the main frontal band out in the SW of the country, edging east.

FRI 07:30 BST: Further showers now reported at Budapest - these veryÌýevident on the lens of the weather webcam (see link above).

FRI 06:10 BST: Lastest official observations from Budapest/Lorinc, south of the circuitÌý(0500 GMT), report showers; temperature 18C, dewpoint 15 C; wind light NW; 7/8 cloud cover.

FRI 03:45 BST: Model timing and evolution currently looks good. A dry dawn in Budapest but (as the radar and lightning links above amply testify!)Ìýa lively thunderstorm is rumbling just west of the capital, in a pre-frontal showery zone ahead of more extensive rain - some heavy - draped through the western half of the country. As per the forecast below, this will all slowly edge eastwards later today with waves of forcing tending to intensify areas of it at times.