Wednesday will start with mostly cloudy skies and breezy conditions, as winds will pick up to 15 to 20 mph (24-32 kph) due to the low pressure developing off the coast and high pressure to the north over England. Some scattered showers will be possible in the afternoon and evening, but I expect that most of them will be light.
On Thursday, temperatures will get much warmer, into the lower 80s as winds turn more toward the south and some sunshine breaks through in the morning and early afternoon. Showers and thunderstorms will develop with the daytime heating, and due to this instability, some of the storms could be strong. Expect lightning, gusty winds, and heavy bursts of rain at times. Showers will continue Thursday night and into Friday morning as low pressure at the surface tracks across northern France. The chance of rain will be highest in the morning, then decreasing through the afternoon. Right now, the amount of rain that is generally expected Thursday and Friday is between a half inch up to one inch.
Saturday actually looks pretty nice, with partly cloudy skies through the day and pleasant temperatures in the mid 70s. I expect a dry start to the race, but there is a slight chance of showers late in the day and in the evening. The chance of rain will be rising overnight as the upper level low pressure system off the coast begins to track east. Rain is likely before sunrise Sunday morning, which could make for some very tough racing conditions. It will probably be more of a steady moderate rain. The rain is expected to continue through Sunday morning, and gradually taper off through the afternoon. Temperatures will be cooler on Sunday due to the rain, with highs in the upper 60s. Total rainfall amounts on Saturday night and Sunday are expected to be between a half inch and one inch.
I'll have another update in the next few days. You can follow @Race4caster to get updates on Twitter, or check the hastag #LeMansWx.