By Doug Schneider

Not much has changed in the weather pattern shown by the models for this weekend in St. Petersburg, so the forecast that I made on Monday still appears on track (no pun intended). A low pressure system will be over the Gulf of Mexico, with a high pressure system over the eastern United States. While I can't rule out an isolated shower or thunderstorm in the area both Saturday and Sunday, I don't expect that they are likely to have an impact on the racing. Pop-up showers along the Florida coast are difficult to predict days in advance, so while they are possible in the St. Pete area, their coverage should be isolated enough to make the chance of one occurring at the track very low. Overall, it should be a good weekend for racing. 

By Doug Schneider

The INDYCAR season finale at St. Peterburg is expected to have general good weather conditions, although an isolated shower or thunderstorm can't be ruled out.

The general weather pattern across Florida and the Gulf of Mexico later this week will feature a weak low pressure area over the Gulf that will be slowly tracking toward Florida. Over the weekend, it will be located just off the Florida coastline. It is a weak and poorly-defined low, which adds some uncertainty to the forecast. But it may be enough of a factor to produce some showers and thunderstorms near the St. Pete area, or maybe just offshore. This far out in the forecast, there is enough uncertainty about their location to warrant a small rain chance. However it doesn't look like they should have much impact if they do occur. 

​Check back through the week for forecast updates.

By: Stephen McCoy

There have been a few changes to the temperatures for the weekend, but overall the forecast for Indianapolis Motor Speedway is still fairly consistent to the initial forecast from Monday. There is a slight chance for isolated showers on Friday, however rainfall rate for the day is expected in the hundredths of an inch, if any occurs.

The synoptic setup for the rest of the forecast period remains the same: a cold front passed through today, which will bring west to northwesterly winds to the region for tomorrow, resulting in cooler overall temperatures. A low pressure surface trough will approach central Indiana on Thursday from the north, bringing a chance for scattered showers in the afternoon. Rainfall totals are expected under a tenth of an inch, but still could disrupt some of the scheduled on track sessions. Behind the trough, high pressure will build in, causing surface winds largely from the north to northwest, continuing to cool temperatures with a morning low in the mid 40's °F and a high in the mid 50's °F.

The area of high pressure is anticipated to move over or close to the Indianapolis region, resulting in calm and variable winds during Saturday morning, with winds then shifting to the south to southwest in the afternoon as the system continues eastward. Saturday night, a warm front extending from a low pressure system to the west will pass through the area, causing Sunday's low temperatures to remain relatively unchanged from the previous day's high. Southwesterly winds behind the warm front and ahead of the pairing cold front will allow temperatures to warm a few degrees before cooling again as the cold front passes through. Both mentioned fronts could bring a chance for precipitation on Sunday, especially in the morning, however rainfall totals will be largely determined by the location of the surface low's center.

By: Stephen McCoy

Cool, early-fall conditions are expected for this weekend's races at Indianapolis Motor Speedway, with chances for precipitation present at the beginning and end of the forecast period.

On Wednesday, a surface low pressure system will pass north of the Great Lakes as it tracks eastward towards the Atlantic Ocean. A trailing cold front will move through Indiana during this time period, setting up cooler temperatures for the region in the following days. West to northwesterly winds overnight Wednesday and into Thursday will result in morning low temperatures in the upper 40's °F and a high in the low 60's °F as the winds continue through the day. Behind the front, there is the possibility of a surface trough extending westward through the Great Lakes region from the aforementioned surface low and moving southward into Indiana during the day. The movement of the trough could bring a chance for scattered showers to the Indianapolis region, especially during the afternoon and may impact the various on-track sessions during this time.

As the surface low continues towards the east coast, high pressure is expected to slowly build into the region over the first part of the weekend. With the center of the surface high to the west, winds on Friday will be largely from the north to northwest, accompanied by partly to mostly cloudy conditions in the low to mid levels for much of the day. The cooler temperatures will continue with a low similar to Thursday and a high in the mid 50's °F. The surface high is anticipated to move over the central Midwest Friday night into Saturday, resulting in calm and variable winds for most of the early part of the day before shifting to the south as the high moves eastward. The lack of wind movement will extend to the low levels of the atmosphere, causing mostly cloudy to overcast conditions; temperatures will be similar to Friday.

Leading up to Sunday, an upper level shortwave trough will allow a low pressure system to develop at the surface over the northern Plains late Friday evening. Due to the trough's orientation, the surface low is expected to track southeastward, centering itself over Illinois on Sunday. Current model output disputes the exact location of the low, but general consensus indicates the center of the system will be either to the west or southwest of Indiana. As a result, a warm front will likely extend from the low somewhere over central Indiana; model output shows a disparity in the low temperature for Sunday as a result of the front, with a range of 10 °F in the most recent runs. In any case, the system is expected to bring a chance for precipitation and overcast skies through much of the day.

By Doug Schneider

A slightly later shift in timing of showers has brought a chance of rain back into Sunday morning with today's forecast update. Still, I don't expect that this will impact the race in the afternoon. 

Scattered showers and thunderstorms will be possible Saturday afternoon, getting more numerous later in the afternoon. I'd put the chance of rain during the race at 40%. I don't think it will be heavy enough to stop the race, but it may necessitate a change to rain tires or perhaps a caution flag. 

The majority of rain along a cold front will pass through on Saturday night and Sunday morning. The question with this forecast all week has been when the front will pass through and the rain chance will end. Today that timing looks a little later than it did a couple days ago, with the front expected to move through between 8 am and 11 am. The session that may be at risk is the morning qualifying session. It will be very close to being impacted, but I'm going to take the optimistic side that the rain will exit before 10 am, with the qualifying scheduled for 10:15 am. It is possible that wetness on the track could cause a short delay. The rest of the day looks great, with increasing sunshine and highs in the mid 70s.