Formula One Weather Forecast: Spanish Grand Prix 2010

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

---------------------------------------

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).

------------------------------

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.

---------------------------------------

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.

---------------------------------------

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...