By: Stephen McCoy

Expect a warm start to the weekend for this weekend's MOTUL Petit Le Mans before a cold front passes through the region on Friday, which will bring a chance for showers ahead of it either Thursday afternoon or overnight into Friday morning. Cooler temperatures are anticipated after the front passes, with only a high in the low 60's for race day.

High pressure will move into the region on Tuesday, remaining present until Friday when a cold front approaches from the west. As a result of the high, and drier air aloft, clear conditions will be present for the day with light winds from the east to northeast. A temperature inversion is expected over the region Wednesday morning, and if dew point temperatures are warm enough, some patchy fog may be possible. Slightly cloudier conditions are anticipated for Thursday as the cold front begins moving through the southeast. Surface winds will once again be light, though from the east to southeast, but increasing and shifting towards the southwest overnight into Friday morning. There is a chance for scattered showers ahead of the front on Thursday, with another light round of isolated showers possible on Friday morning.

The possibility of overnight rain will also bring the possibility of fog Friday morning as the southerly winds ahead of the front cause the surface to become more saturated. After the front passes through, winds will increase from the northwest, with cloud cover gradually decreasing into the afternoon and evening. The cooler air behind the front will result in low temperatures for Saturday in the low 40's and warming to a high around 60 along with clear conditions for much of the day.

By Doug Schneider

The path and timing of Hurricane Delta is coming into better focus today. The good news for Charlotte is that its track has shifted farther to the west. So while rain is still likely at the track this weekend, the impacts of the rain appear lower as the heavier rain is expected to stay to the west, with mainly light on/off showers expected at the Speedway. 

Delta is forecast to make landfall along the Louisiana coast on Friday, then track across Mississippi, Tennessee, and eastern Kentucky through Sunday. The cloud shield on the outer fringes of the hurricane will start to spread over Charlotte on Friday. The morning will start with mostly sunny skies, but high clouds will increase through the day. Rain should hold off until after the evening IMSA practice session. 

Some of the outer rain bands from Delta will start to spread into the area late Friday night or Saturday morning. Through the day, there will be numerous showers around the track, but they will be on and off - it doesn't look like a washout at all. I expect that the majority of this rain will be light, with the total amount of rain expected all day being around one or two tenths of an inch. When I made Monday's forecast I was afraid that heavy rain would be possible, but due to the westward shift of the forecast track, I am much less concerned about that now. This is why I have lowered the Impact rating to low. It will make for some interesting tire strategy during the racing, but it should all be able to be held as scheduled. It will be breezy on Saturday, with a southeast wind at 10-20 mph, gusting up to 30 mph at times.

On Sunday, there will still be showers in the area, mostly in the morning, but they should be scattered and occur less frequently than on Saturday. It is possible that showers could end in time for the Cup race in the afternoon, but I can't say I'm very confident in that yet. An isolated thunderstorm can't be ruled out, but the chance of one at the track is low. 

By Doug Schneider

I'm going to say up front that this is a low confidence forecast, which means that it is likely to have some changes as we get closer to the race weekend. But as of today, it appears that there will be potential for a rather wet event, especially on Saturday. I would love to forecast a dry event as I will be there in person, but I'm afraid it's not looking like the weather will cooperate.

The weather system that will be impacting Charlotte this weekend is now taking shape in the Caribbean Sea, currently Tropical Depression 26, which is forecast to become Tropical Storm Delta. It will be tracking north across the Gulf of Mexico through the week, and is forecast to make landfall as a hurricane on Friday along the Louisiana coast. After it makes landfall, it is expected to curve toward the northeast, and move across Alabama, Georgia, upstate South Carolina, and western North Carolina. The models agree on this general pattern, but the big uncertainty with it is the timing. It appears that rain could arrive as early as Friday evening, potentially during the IMSA practice session that starts at 7:30 pm. Rain showers are likely through Saturday, which will make for some interesting conditions during the Xfinity race and the IMSA race in the evening. It's too early to say how much rain will fall and what the impacts will be, but because it is a system with tropical origins, heavy rain may be possible. It will also be breezy on Saturday, with a southeast wind between 10 and 20 mph, gusting up to 30 mph at times.

The low pressure center is expected to track into Virginia by Sunday morning, and there should be a decreasing chance of rain through the day as it continues a northeast track. But because of uncertainty with timing, I will keep a chance of rain all day on Sunday. There could be showers in the area during the Cup race. 

These tropical systems are often difficult to forecast with high accuracy this far out in the forecast. As a result, my confidence level in this forecast is low, so it will likely change through the week. Be sure to check back for updates through the week. 

By Doug Schneider

Some good news with today's forecast update for Road Atlanta - the weather pattern in trending in a drier direction, with just a small chance of showers and thunderstorms on Saturday, followed by pleasant conditions on Sunday. 

Hot and humid weather will continue through this week and into Friday, with mostly sunny skies and high temperatures in the lower 90s. The afternoon dewpoints will be in the lower 70s, which will put the heat index near 100 degrees. 

On Saturday a cold front will move across the area from north to south. As it does, it may spark off a few showers and thunderstorms across north Georgia. Coverage should be fairly isolated, and and showers should be short-lived, so I expect that any potential impacts on the racing will be low. The afternoon hours will be the most likely time frame for potential showers and thunderstorms. 

The main change in the forecast is for Sunday, as it now appears likely that the front will push well to the south and west of Road Atlanta, and high pressure will build into the area more aggressively than previously shown by the models. The result of this will be a very pleasant day on Sunday, with cooler temperatures and lower humidity. Showers should stay well south of the track closer to the front. 

​I plan to have another update posted on Friday. 

By Doug Schneider

The weather at Road Atlanta late this week will start off hot, but an approaching cold front will bring cooler temperatures through the weekend, but an increasing chance of showers and thunderstorms as well. 

High pressure will be located off the Southeast coast for the middle of this week and into Friday, providing warm temperatures in the lower 90s and mostly sunny skies. There could be an isolated afternoon shower in the north Georgia area, but I expect that these will be mainly in the higher terrain to the north of Road Atlanta, and not affect the track. 

A cold front will be moving southeast across the Tennessee Valley on Friday, and move across northern Georgia on Friday night. The exact position of the front is uncertain this far out, but as of today it is expected to be to the south of Road Atlanta on Saturday. Because of the uncertainty, I will mention a possibility of afternoon showers and thunderstorms, but only a 20% chance. If the front stalls closer to the track, the chance of rain will be higher.

On Sunday the front should start to push back to the north and the flow above the surface turns to the south, which will bring greater moisture into northern Georgia. As a result, the chance of rain will rise, as will the amount of clouds. Scattered showers and thunderstorms are expected, mainly in the afternoon but are possible at any time of the day. As we get closer to the weekend, rain amounts and potential impacts on the racing will come into better focus. For now, I have rated the impact as low.

Check back on Wednesday for the next update.

By Doug Schneider

Not much has changed in the foercast for VIR since Monday, with a high chance of rain on Friday tapering off to a lower chance on Saturday, and an even lower chance on Sunday. Timing of the best rain chances has come into better focus, along with potential rain amounts. 

Friday will likely begin with mostly cloudy skies, and possibly a few showers in the area. But through the day, the coverage of showers and thunderstorms will be increasing, making the afternoon the most likely time for storms to have an impact. The hours between 3 pm and 7 pm appear to be the most likely time. With high moisture content in the atmosphere, these storms could produce very heavy downpours. Rain amounts between a quarter and a half inch are expected, although it is possible for a strong storm to drop a half to one inch if it moves directly over the track. Storms may also produce frequent lightning and gusty winds of 30 to 40 mph.

On Saturday, a low pressure system to the west of the Appalachians will continue to trek northeast, so it will have less of an impact on the NC/southern VA region. However, there will still be a southerly flow of moisture into the region, so scattered showers and thunderstorms are expected again in the afternoon. If a storm moves over the track, there could be some wet racing, but these storms should be weaker and shorter-lived than on Friday. A tenth to a quarter inch of rain will be possible.

With the low pressure system moving farther away, Sunday is expected to be mainly a dry day. With afternoon heating, some storms may develop over the mountains to the west, and these may gradually move eastward. I can't completely rule out a shower reaching VIR late in the day, but I think it will be late enough that it won't have an impact on the racing. There will be more sunshine on Sunday, so highs will reach the upper 80s. 

By Doug Schneider

It pains me to be making a forecast for Michelin GT Challenge weekend at VIR, and not be able to attend. Even though I drive 5 hours to get there, I consider VIR my home track. Mixed weather conditions can be expected for the event, with Friday having the highest chance of rain, Saturday being a lower chance, and Sunday expected to be dry.

To start the period, a deep low pressure trough will be located west of the Appalachian Mountains, with high pressure off the Atlantic coastline. This will provide a southerly flow of moisture deep through the atmosphere, and with a jet streak in the upper levels producing some lift, showers and thunderstorms will be numerous on Friday. They will be possible at any time of the day, but the highest chances will be in the afternoon. I expect that there will be enough rainfall that there will be some delays and stoppages to the day's sessions. 

On Saturday the upper trough moves a little farther east, which should move the main axis of rainfall closer to the coast. There will still be a good amount of moisture in the atmosphere, but not much in the way of lift. So I think that the coverage of showers and storms on Saturday will be more scattered, and occur mainly in the afternoon when heating can provide more instability.

On Sunday the trough will be weakening and moving off to the east, which will result in a more westerly flow that will bring drier air to the region. It will be quite a nice day with partly cloudy to mostly sunny skies, and highs in the upper 80s with slightly lower humidity. 

By Doug Schneider

Not much has changed in the forecast for Friday and Saturday at Sebring since my initial forecast on Tuesday. A tropical upper level low pressure system is expected to move slowly west across southern Florida, which will enhance the chance of afternoon showers and thunderstorms both day.

The main impact of any showers and thunderstorms will be lightning and very heavy rainfall. Because of the potential for heavy rain to cause ponding of water on the track, and relatively high confidence of storms occurring, I have rated the Impact as Moderate. Some sessions or races may need to be stopped for a period. The good news is that any showers or storms should be short-lived, lasting maybe 20-40 minutes on average. For both Friday and Saturday, the most likely time period for showers and storms will be between 2 pm and 6 pm.