By Doug Schneider

Not much has changed in the expected weather pattern this weekend over Indiana. An upper level trough and a surface cold front are expected to cross the area Saturday night and Sunday. The frontal passage on Saturday night will bring some showers, and the upper trough will linger over the area through Sunday. This trough will create some instability that will produce scattered showers around central Indiana during the day. The chance of a shower at the track is about 30%. Showers are possible any time of the day, but the best chance is in the afternoon. I expect that any showers on Sunday will be light and short-lived, with low impacts on the racing. I don't expect any delays or red flag periods due to rain or lightning. 

By Doug Schneider

A nice weather weekend is expected as IMSA returns to Indianapolis Motor Speedway. A large high pressure system will be sitting over the area to start the event on Friday, providing mostly sunny skies and pleasant temperatures and humidity. Through the weekend, this high will shift east, and a low pressure trough in the mid and upper levels will approach the area on Sunday. This will bring an increase in cloud cover, and possibly a few showers. The good news is that moisture appears limited as the trough moves through on Sunday, so if there are any showers at all, they should be light and short-lived. I don't expect any significant impacts to the race at this time, but I'll keep an eye on it as we get closer to the weekend. Stay tuned for updates through the week.

By Scott Martin

Looking at the latest model runs for this weekend, we may have to put up with a passing storm on Saturday as a cold front will be working through the area, but will make it feel much nicer and less humid on Sunday. The good news is that the models are not too bullish on the rain activity on Saturday, but convective storms are usually not handled well by the models sometimes. I'll keep a chance of storms in the forecast on Saturday afternoon and early evening.

Sunday will be a very nice day with temperatures in the lower 80s and low humidity. There will be a mix of sun and clouds, and I just can't rule out an isolated shower during the afternoon to early evening, but with the amount of dry air in place, chances will be very, very low.

By Doug Schneider

Some changes were made for this forecast update for IMSA's VIR weekend. While the chance of rain has lowered on Saturday, the chance has increased on Sunday. 

The models have not done a great job with how they handle a cold front that moves southward through Virginia and North Carolina this weekend. This makes for an uncertain forecast. What I am confident about is that temperatures on Friday will be hot, with highs in the mid 90s and a heat index around 100 to 105. Most of the day will be dry, but there is a slight chance of showers and storms moving into the area late in the day, mainly after 5 pm.

A weak front or low pressure trough will be associated with these showers, and will move through in the evening hours. It will shift winds to the north, and bring slightly lower humidity for Saturday. There will still be some instability in the afternoon that may allow for isolated showers and storms to develop. Again, most of the day will be dry, with only a small chance of showers late in the afternoon. 

Another front moves in from the north on Sunday, and may initiate showers and thunderstorms in the afternoon. With more cloud cover, temperatures will be cooler, in the 80s. 

By Doug Schneider

It's going to be a hot week in the St. Louis area, but the good news is that cooler temperatures will arrive in time for the Bommarito 500 activities. High temperatures at WWTR on Thursday and Friday will be near or above 100 degrees. On Saturday morning, a front is expected to move through the area, which will shift winds to the northeast and bring a cooler and less humid air mass. With moisture being very limited, no rain is expected with the front at this time, but this will need to be monitored for changes through the week. Sunday will be a very nice day to be at the track, with highs in the lower 80s and comfortable humidity levels. There will be a northeast breeze both days, between 10 and 15 mph.

By Doug Schneider

Mixed conditions are expected at VIR for Michelin GT Challenge weekend. It will start off hot and humid, followed by a frontal passage that will bring showers and storms, then cooler and drier air will build in behind the front.

Friday's chance of showers will be mainly in the afternoon, as the atmosphere heats up and creates instability. With winds from the southwest, temperatures will climb into the mid 90s, with a heat index approaching 100. Afternoon showers are expected to develop near or along the Blue Ridge and track east into the Piedmont. Coverage is expected to be scattered, and the chance of a shower or storm at the track is about 30% at this time.

The chance of rain increases on Saturday as a cold front moves southward across Virginia. There are some disagreements among the models regarding the coverage of showers with this front, and the timing of the best chance of rain is still uncertain this far out. The expected cloud cover and frontal passage will bring temperatures down from Friday's highs, but the humidity will still be quite high. 

The passage of the front on Saturday is expected to be followed by a more pleasant air mass on Sunday, as high pressure over the northeast builds southward into Virginia and the Carolinas. Under mostly sunny skies, highs will be in the lower 80s, with more comfortable humidity levels. 

By Doug Schneider

There will be a few rounds of showers in Indianapolis over the weekend, but the timing of these showers looks favorable for little to no impacts on the racing at IMS. 

An upper level disturbance will be crossing the Illinois/Indiana area Friday night, and thunderstorms are likely to occur during the overnight hours. There is a small chance that some showers could linger around Speedway after sunrise, but they should be gone by the time of the first on-track session (Xfinity practice) at 9:35 am EDT. The rest of Saturday should be dry and mostly sunny, with temperatures reaching into the mid 80s. There could be a few showers in the area Saturday evening as a front moves into the area, after the end of the Xfinity Pennzoil 150.

Another upper level disturbance will cross the Mississippi River on Sunday, and track east through the afternoon. Showers with this system are expected to move into central Indiana late in the day or during the evening, most likely after the end of the Verizon 200. If the timing of this system shifts a little earlier, it could impact the late stages of the race, but I think the chance of that happening is low. 

By Doug Schneider

Overall, good weather is expected at IMS for the combined INDYCAR and NASCAR events for Brickyard Weekend. The main risk of rain at the track will come on Friday night as an upper level trough swings across the area. The most likely timing of this rain should not affect any on-track action, however a few showers will be possible into Saturday morning. The chance of rain should be gone by the time the INDYCAR race starts at 2 PM. Sunday's weather looks great for the NASCAR race, with mostly sunny skies. Temperatures through the weekend will peak in the mid to upper 80s.