Interlagos too could become another showery affair, with rain expected on Friday, and a slight chance of showers moving in on Saturday and Sunday.
There is widespread agreement that Friday will be wet with frequent showers, but quite how much rain there will be depends on who you believe. Weather-forecast.com are one of the most reliable among the mainstream weather sources, suggesting eight millimetres of rainfall on Friday - most of it falling in the afternoon. Local sources such as Climatempo go a bit further on the prospect of rain, forecasting 17 millimetres of precipitation.
Saturday and Sunday should see less in the way of showers, with mainly dry conditions and a light sprinkling from time to time. The fine detail for the weekend is not yet known, and will become more apparent as we move towards qualifying and of course the race itself.
Another aspect of the weather that could be critical to the outcome of the world championship is temperature, which is expected to be on the cool side during the event. Friday will see the mercury peak at 22 degrees Celsius, with the top temperature falling to 19 degrees on Saturday, rising slightly to 20 degrees on the all-important Sunday.
24 hours on from the initial forecasts on Monday, the news is that Friday is expected to begin largely dry, with rain arriving by afternoon, and continuing through the evening. Temperature predictions for the weekend are now slightly higher than anticipated, with a maximum of 20 degrees Celsius on the first day.
Saturday continues to be the best day weatherwise, with cloudy conditions but staying largely dry. There is a slight risk of a light sprinkling during the course of the Formula One running, but nothing to cause any concern at this stage, with the guage again peaking at 20 degrees.
The predictions for Sunday have changed, taking a noticeable swing towards wet conditions. Almost all sources are now agreed that the championship decider will be wet. Showers and longer spells of rain are set to move in early, and remain in the vacinity through much of the day. Weather-forecast.com show the current breakdown of the anticipated rain, and Climatempo also back this rainfall from a local perspective.
It should be mentioned that the two forecasts linked show the situation for the city of Sao Paulo. Our own projections for the circuit itself on Sunday predict 14 millimetres of rainfall between 03:00 and 15:00 on Sunday.
The temperature on raceday is also set to rise, with 24 degrees Celsius expected at Interlagos.
As we said, the forecasts are moving around at the moment, and further changes are likely as the models and resultant mainstream forecasts react to the latest model data.
The first heavy rain of the week arrived on Wednesday evening, soaking the circuit, however by this morning most of the rain had cleared away and, as the drivers arrived for their round of press conferences and media briefings, the mainly cloudy skies were punctuated by some brief sunny periods. As Thursday continued, the day turned much more overcast.
An area of low pressure is set to dominate the event between Friday and Sunday, bringing cool temperatures into the area. Towards race day, a weak cold front will increase the chances of a wet final race of the 2008 season. Currently, low pressure is slowly moving north east, affecting northern Argentina and southern areas of Brazil.
On Friday the low will remain roughly where it is now, with showers on its outer edges. Scattered showers and cloudy skies are expected over the circuit throughout the first practice day. These showers will be light in nature. The maximum temperature will struggle to reach 20 degrees Celsius thanks to the large swirl of cool air that will be a factor of the weekend.
For Saturday, the low continues to slowly move north east, with the centre of pressure located very close to Sao Paulo. This will bring a slightly better day in terms of weather, with a low risk of a shower and even some sunny intervals during the afternoon for qualifying. Despite the prospect of seeing some sunshine, the air temperature is not expected to rise above 20 degrees.
Late on Saturday evening, the cold front, on the trailing edge of the low pressure system, will have moved in over the the Sao Paulo area.
The main weather news today is that a significant amount of rainfall is now expected throughout Sunday, beginning from dawn and lasting until after the Grand Prix has concluded. The maximum air temperature will rise slightly with the heavy blanket of cloud cover, up to 23 degrees Celsius.
The latest weather model forecasts for the circuit indicate that the rain on Sunday is being pushed back, later and later in the day, and the expected volume of rain has reduced. The high pressure area may slow down the swift northward progression of the cold fronts. This is obviously critical to the race, and the forecasts that we have seen all week about rain on Sunday.
In summary, Saturday will be mainly dry with little or no rain, thanks to the arrival of high pressure bringing more settled weather. Overhead it will be partially cloudy and some sunny spells are likely to develop. The maximum air temperature will be 21 degrees Celsius.
The risk of rain is beginning to recede for Sunday as the high pressure block develops. Meteo France and the Formula One teams are already aware of this change in events and are watching the situation closely.
Nico Rosberg was asked after practice about his chances for the weekend and said: "If it rains I think we have a better chance. Our car is normally pretty good in the rain but now the forecast is less and less rain, so that's not great for us, but we will see."
The mainstream weather forecasts may tone down their expectations of rain in the coming hours, as they react to the recent climatic changes. The situation is delicately poised, with that area of high pressure now key to the outcome of the race - and possibly the world championship. If the active cold fronts push the high away to the north, allowing them to sweep through, Sunday is likely to be wet. However, if the high pressure holds firm over the next 24 hours, the rain will continue to be pegged back, arriving later, once the championship battle has been concluded.
Tomorrow, rain is expected to arrive early in the morning in Sao Paulo, shortly after dawn. The showers will be light at first, before heavier rain moves as the day progresses. The hours between 13:00 and 17:00 GMT are set to see the heaviest rainfall during the day, so the worst of the wet weather should be just beginning to move away as the race start occurs. Light rain is then expected at times throughout the race. In total, around 17 millimetres of rain is anticipated between dawn and the end of the race.
The temperature will be very similar to today's mark, at 22 degrees Celsius.
The forecast of rain will add to an explosive atmosphere tomorrow, with the partisan crowd creating a lot of enthusiastic noise and, of course, it adds yet more the pressure to the title battle.
The forecast relies on a complex sequence of atmospheric events and the picture will become clearer in the morning when the rain bands can be tracked on radar.
Accuweather ilmoittaa että on pilvistä (vähän aikaa sitten luki että sateista), mutta Autosportin raportti tulenee tässä näillä hetkillä kertomaan tarkemmista sääoloista.Millanen keli siellä tällähetkellä oikein on?
Mainly cloudy conditions with some sunny spells have greeted the teams and drivers arriving at the Interlagos circuit early this morning, but to the south and west, the large swathes of cloud cover and rain are slowly moving towards the circuit.
The latest satellite sequence provided by INMET of Brazil shows two large areas of cloud bringing the rain that we spoke about at length last night. The first area to the south of Sao Paulo is extremely slow moving, but is gradually working its way northward - towards Interlagos.
To the north west, another area of cloud, also bringing rain, is moving in an easterly direction, again towards the circuit.
This regional radar image vividly demonstrates the rain moving in the direction of Sao Paulo.
The weather is closing in slightly slower than anticipated, but almost every weather source on the planet now predicts rain later as we move towards the start of this vital race.
Jatkan sääkeskustelua varsinaisessa kisatopicissa, ettei mene molempiin topicceihin samasta aiheesta tavaraaDrops of moisture are now falling around Interlagos. Very similar to Friday's rain at this stage, extremely light and not enough to wet the circuit at this stage, but weather is continuing to turn for the worse.