By Doug Schneider

A wet weather pattern is expected to develop over Florida late this week, which could potentially have some impacts on the Cadillac Grand Prix events on Friday and Saturday.

There will be some dry air over Florida on Thursday, which will keep the chance of showers and thunderstorms low. Afternoon showers are pretty common this time of year at Sebring, so just a 20% chance is lower than normal. Still, if one of these showers moves over the track, it could produce brief heavy downpours. Sunshine in the morning hours will raise temperatures well into the 90s, with very humid conditions. The heat index could rise to the 100-105 range in the afternoon. 

An upper level tropical low pressure trough will be moving from east to west across the Atlantic and across Florida on Friday and Saturday. This system will bring deep moisture and instability to the area, making afternoon showers and thunderstorms likely both days. The main impact from any showers ans storms will be lightning and heavy downpours that could produce a very high amount of rain in a short period. With the high probability of rain and the potential for it to be heavy, I have the expected impact as Moderate, as ponding of water on the track could result in some delays. The increased cloud cover will help hold temperatures back to around 90 degrees.but that won't be much consolation with the high humidity.

By Doug Schneider

The main change to the forecast since Tuesday is a shift in the timing of the best chance of showers and thunderstorms on Saturday. Fortunately, this change is for the better, as the majority of rain is expected to pass through south-central Virginia on Friday night and early Saturday morning, with a low chance of impacts on the racing action. 

Some pop-up afternoon showers and thunderstorms will be possible on Friday, mainly near the higher terrain to the west of Danville. They will be moving east, but the chance of one of them reaching VIR before the end of the day's sessions is unlikely.

A passing trough and cold front are likely to bring showers and thunderstorms overnight and into early Saturday morning. There is a chance that some of the morning sessions could be impacted by these showers, possibly the GT qualifying from 8:30 to 9 am, and possibly the GT4 Sprint race at 9:25 am. Through the rest of the day, clouds will clear out and it will be mostly sunny, with high temperatures around 90 degrees. 

Drier air behind the departing trough will keep Sunday dry and sunny, with a high temperature around 90 again. 

By Doug Schneider

The season opener for GT World Challenge at VIR may be affected by some showers and thunderstorms, particularly on Saturday, but the vast majority of the racing action should be completed in dry conditions. 

A low pressure system is expected to be moving northeast across South Carolina and eastern North Carolina on Thursday. Even though it's just a couple days away, there are some big differences between the models in their placement of this low, and how much rain it brings to VIR. I'm going to be optimistic with my forecast, and only have a 30% chance of afternoon showers and thunderstorms. This is how most of the models are leaning, but the NAM shows much greater shower coverage. Hopefully it's an outlier. 

On Friday the low pressure system will be moving up the East Coast, and will no longer affect southern Virginia. With a lack of any significant high or low pressure systems in the area, I expect that Friday will be a typical summer day, with a few isolated showers or a thunderstorm possible in the afternoon, and a high around 90 degrees. 

Saturday appears to have the best chance of rain as an upper level trough and a surface cold front approach from the west. This system will provide lift and instability that will favor the development of showers and thunderstorms, mainly in the afternoon. There is a little uncertainty about the timing of the trough passage, and if it comes earlier there could be some morning showers as well. But the afternoon will be the more likely timing. 

Drier air aloft will build across the area behind this system, and which should result in a dry and mostly sunny day on Sunday. It will still be rather hot, with a high around 90.

By Scott Martin.

The NTT Indycar Series along with the USF2000 and IndyPro 2000 makes a trip to Road America for the REV Group Grand Prix weekend.

USF2000 & Indy Pro 2000 (Thursday & Friday)
An active pattern looks to bring a good chance of rain and thunderstorms mainly during the afternoon and early evening hours on Thursday for testing and practice sessions for both series. Temperatures will start off around 80 degrees and warm to around 89 degrees for the daytime high. Winds will be out of the southwest to south at 5-10 MPH. Rain chances will start off around 40% early but will max out at 70% by the early afternoon and persist through the end of the racing day.

Rain may hold off for most of the day on Friday until the late afternoon hours before the end of the racing day. I'm still going to include a very small chance of rain early but those odds will max out around 30% during the afternoon hours. Winds will be out of the west at 5-10 MPH. Temperatures will start of around 75 degrees and will warm up to around 85 degrees by the afternoon.

NTT Indycar Series (Saturday & Sunday)
Whether you would like to see the fastest racers in the world drive in the dry or in the wet, it looks like the dry-weather fans may win out this weekend. Saturday and Sunday will feature a great deal of sunshine early on, but convective clouds will slowly build during the late morning and early afternoon hours. There will be a very small chance of a passing shower or thunderstorms, but those will not be very likely. Saturday's temperatures will start off around 82 degrees for the first session and top out around 83 degrees during the afternoon. Sunday's temperatures will be around 76 degrees for qualifying and topping out around 80 degrees by the afternoon. Chance of rain on both days is barely at 20%.

By Doug Schneider

Showers and thunderstorms are likely in the Daytona area on Friday and Saturday afternoon and evening, which may have an impact on the IMSA WeatherTech240. Not much has changed in the expected weather pattern since my initial forecast on Monday. There will be a slow-moving low pressure system across the Deep South with a weak front near northern Florida. Since Daytona will be on the southern side of this system, hot and humid conditions can be expected during the event. Not too surprising for Daytona in July.

The chance of rain has increased a little on Friday as it looks like the front will be closer to Daytona than the models previously showed. Highs will reach the lower 90s, with a heat index around 100. Afternoon showers and thunderstorms are expected to develop in the area, and any of them could produce a brief heavy downpour. The only on track activity on Friday is a practice session from 6:15 to 7:15 pm, which is during the time frame when storms are possible. If a storm passes over the Speedway, a quick quarter to half inch of rain will be possible, along with gusty winds and frequent lightning. 

Saturday looks pretty similar to Friday, although there may be a little more cloud cover to hold temperatures down a little bit, but it will still reach 90 degrees. Like Friday, numerous showers and thunderstorms will develop in the afternoon and linger into the evening. Heavy downpours, gusty winds, and lightning are possible with any storms that pass over the Speedway. 

If you're at the track, stay weather aware and have a plan to find sturdy shelter before storms reach the Speedway.