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As it happened: Japanese Grand Prix Weather
By Emlyn Hughes
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Mon 15:00 Weather has played a significant role in the running of the 2010 FIA Formula 1 world championship, but sunshine and pleasant temperatures are on the menu in the lead-up to this crucial event as the teams arrive at Suzuka for this weekend's Japanese Grand Prix.

Typically, rain falls at some point during the weekend at Suzuka and the thought that we may see a wet event was amplified over the last week as several rainstorms blew in across the Mie Prefecture. A total of 103 mm of rain has fallen at the figure-of-eight circuit over the last seven days, but today was much better as the last of the recent rain moved away to the east, allowing in brighter conditions as the teams begin to set up their garages.

The days leading up to the start of practice will likely deliver sunny spells and pleasant temperatures of around 23 Celsius, with little or no rain to speak of. However, there will be a change towards the weekend as a substantial weather system moves from west to east, just to the south of the Japanese coast.

Early Forecast

Current precipitation projections indicate, while there will be a lot of rain just to the south of Suzuka between Friday and Sunday, the circuit itself should fare reasonably well, with predominantly dry and cloudy conditions overhead.

There will be some sunshine on offer, predominantly on Friday. Both practice sessions are expected to take place in dry and bright weather, with a maximum temperature reaching 23 Celsius.

Conditions will change somewhat on Saturday as much more cloud appears in the region. Early predictions are for a mainly dry final practice and qualifying period, but some overcast spells may just produce a light sprinkle in the afternoon, with a top temperature of 20 Celsius.

Sunny spells will return at times on Sunday and we expect a dry race at this stage. The slightly better conditions will also have an effect on temperature, with a maximum of 22 degrees during the race.

The expansive weather system just to the south of Japan will need careful monitoring over the coming days. Any deviation northward from its core track could greatly affect how the weekend's weather plays out. AUTOSPORT Live will continue studying the data over the next 48 hours and we will publish a further update on Wednesday morning.

Japanese fans may need umbrellas again
Japanese fans may need umbrellas again © LAT
Wed 10:00 The teams have enjoyed a very pleasant few days at Suzuka - scene of this weekend's Japanese Grand Prix - but changes are afoot as final preparations continue.

Synoptic Trend

All eyes are currently focused on what is happening in the atmosphere to the south-west of Japan. On Monday we mentioned that Suzuka would be located at the 'dry' northern edge of a low pressure system and a large swathe of rain, but that any slight deviation to the north would bring the race weekend into play. There has indeed been a slight deviation and Suzuka is set to be affected - particularly on Friday night and Saturday morning - as a result.

Weekend Forecast

For now, the run of fine, sunny days will continue, with Thursday seeing the last of the sunshine. Friday will dawn dry, but with heavy cloud cover, and conditions will quickly become overcast as the first practice session approaches. It should remain dry with threatening skies until early afternoon, but the rain will be ever advancing from the west and is expected to arrive during mid-afternoon. It is too early at this stage to say whether the final stages of the second session will be affected.

Once the rain arrives, we are set for a 24-hour window of wet weather. The heaviest of the rain is expected during darkness, but by Saturday morning, the risk of prolonged rain will already be decreasing as lighter showers follow on behind. If the current rate of weather model evolution is maintained, it is likely that we could see a wet final practice session on Saturday morning, but a clearing period towards qualifying, with intermittent light showers.

After midday on Saturday, the risk of rain will decrease dramatically. Further light showers are possible in the afternoon and this will extend overnight into the early hours of Sunday morning, but things should be improving by dawn on race day.

Temperatures will suffer, thanks to the cooler airflow. On Friday we can expect a high of 22 degrees, while during Saturday's wet weather, thermometers will struggle to reach 17 or 18 Celsius. Things will begin to pick up again on Sunday, once the worst of the weather has cleared the Mie Prefecture, with a top temperature of 23 degrees during the race.

Slight detail changes are expected over the next 24 hours. AUTOSPORT Live will, as ever, be monitoring all the important data and we will publish our usual update on Thursday.

A sunny Thursday at Suzuka
A sunny Thursday at Suzuka © LAT
Thu 13:11 Thursday showed the Suzuka circuit in its best light, as an impressive number of spectators filled the main grandstand on the start-finish straight to watch the teams complete their final preparations ahead of practice for the Japanese Grand Prix.

However, the wall-to-wall sunshine and need for suntan lotion will quickly disappear as a developing low pressure system slides north-east from the Pacific Ocean towards Japan over the course of this weekend.

The bands of rain that are on course to lash Suzuka on Saturday have become something of a moving goalpost over the last few days, thanks to the gradual northerly element associated with this system, as it moves across Japan from west to east.

However, it isn't quite time to rebuild Noah's Ark just yet. Friday will dawn dry in the Mie Prefecture, although conditions will quickly become overcast during the early stages of the morning session. Things should remain the same for the second practice in the afternoon and we should get away with a dry first day of track activity, with temperatures reaching 22 Celsius.

Time for raincoats

The change to wet weather will begin on Friday evening, as the first showers make their way in from the south west. Any showers on Friday night will be light at first, but by the early hours of Saturday morning heavier rain will have arrived, to ensure a wet start to Saturday's proceedings.

As has been the case for the past 48 hours, the final practice and qualifying sessions are most at risk of significant rainfall. The rain will not be continuous - there will be lighter interludes from time to time - but it will be a very gloomy day at Suzuka, while temperatures will peak at just 18 degrees during qualifying. Any squally periods of rain may be accompanied by a strengthening wind at times but, generally, the winds will be light, with just a slight breeze from the east.

Intense and potentially damaging rainfall is currently forecast on Saturday night and into the early hours of Sunday morning, as the most severe part of the system passes through the region. Torrential downpours over a six-hour period are predicted, and there is potential for a lot of water collecting around the circuit - particularly at the bottom of the hill in Turns 1 and 2.

Drying out

From dawn on Sunday morning, the transition from heavy rain to drier weather will be reasonably quick. Conditions will steadily improve throughout the morning, as the intense rainfall slides away to the north-east. Breaks in the cloud base will appear and sunny periods are likely to develop as we approach the start time. During the race, the clouds will continue to break above Suzuka, allowing more sunshine through, as temperatures recover to a healthy 23 degrees Celsius.

A scintillating Japanese Grand Prix is in prospect as rain comes just in time to play a major role in shaping the event. Who will show the best performance in the dry conditions on Friday? Join us for all the action as the Formula 1 weekend gets underway, at 00:45 GMT.

Vettel was quickest on a dry Friday
Vettel was quickest on a dry Friday © Sutton
Fri 09:59 Red Bull Racing proved its strengths in dry conditions with Sebastian Vettel and Mark Webber running the show, while the clouds rolled over during practice, signaling a change in the weather.

The first isolated showers fell just minutes after the end of Friday afternoon's second session. Initially, there were some breaks in the light showers, but at 18:10 local time the beginning of the 'real' rain arrived.

Tonight, there will be spells of mainly light rain as a low pressure system develops quickly to the south-west. It won't rain continuously - there will be some breaks in the initial phase, but generally, the rain will slowly but steadily intensify over the next 24 hours. In the early hours of Saturday morning, the rain will start falling moderately at the circuit and we expect a wet track for the final practice session.

A further change is expected as we move into the early afternoon. The rain intensity will become torrential for a time - and latest estimates predict that this change towards really heavy rain will be around the time of the qualifying session.

Depending on what time the worst of this system blows through, qualifying will either be wet or ridiculously wet - to the point where navigation of the circuit could even become impossible on full wet tyres.

Temperatures will take a hammering as the rain sweeps through the region, with a maximum of just 18 degrees during the knockout session. The risk of torrential rain will continue until around nine o'clock on Saturday evening. The weather system is then set to end with a flourish and will quickly clear away to the north-east, leaving the Mie Prefecture with a few isolated showers to deal with overnight into Sunday.

By dawn on race day the worst of the weather will be long gone, and above Suzuka the clouds will begin to break. From mid-morning onwards we expect sunny periods to develop and these will become more prolonged as we go through the day. Temperatures will recover to a maximum of 23 degrees Celsius and it will feel pleasant in the sunshine.

There is little doubt that Saturday will be action-packed. Join us for full coverage of all the fun and games, starting with the final practice session at 01:45 GMT.

Kubica faced some of the better conditions this morning
Kubica splashed through some of the better conditions this morning © Sutton
Sat 09:42 Suzuka turned on the waterworks at precisely the wrong time for Formula 1 as the expected low pressure system developed massively on Saturday, with two inches of rain falling in the space of five hours to wash out both the final practice and qualifying sessions.

Rain clearing

With qualifying postponed until tomorrow morning, the continuing rainfall over the Mie Prefecture takes on new meaning this evening. The intense rain that blighted today's track action has cleared away to the east, leaving a period of light intensity rain to follow on behind as we go through tonight.

This progressively lighter rain will continue to move east and clear the region completely by the early hours of the morning, giving the circuit several hours to dry out. By dawn there will be some breaks in the cloudbase and qualifying is set to take place on a dry track with some cloud around but also increasingly sunny spells. However, around the circuit the gravel traps, grass run-off areas and tyre barriers will retain a lot of water, so a mistake during the knockout session could prove very costly.

Sunny Sunday at Suzuka

A quick turnaround will be required for the teams between the end of qualifying and their usual starting procedure for the race.

During this time, conditions will continually improve with more and more sunshine evident along with partly cloudy skies- a stark contrast to the conditions witnessed today. Temperatures will recover quickly to around 23 Celsius in the afternoon and we expect a dry race from start to finish - just as happened in 2004 the day after Typhoon Ma-On skirted past the circuit.

With the changed programme of events who can take advantage of the situation to qualify and race well on the same day? Join us tomorrow for live coverage of the rescheduled qualifying session at 00:45 GMT.

Monday 04 Oct Start GMT
 Japanese Grand Prix Weather 15:00
Friday 08 Oct
 Friday Morning Practice 00:45
 Friday Afternoon Practice 04:45
Saturday 09 Oct
 Saturday Morning Practice 01:45
 Postponed Qualifying 04:45
Sunday 10 Oct
 Sunday Morning Qualifying 00:45
 Race day at Suzuka 05:00