By Scott Martin - ​@RaceWx4You

The weekend forecast for Road America at this point doesn't look too bad, but we may have to put up with a little wet stuff at some points throughout the event. Believe it or not, the tropical system that is affecting the Gulf Coast is messing with the forecast, so some of the details are not set in stone as of yet. I'll nail those down within the next day or two.

There is a surface boundary that is forecast to stall out over the Wisconsin/Illinois border, and this may bring showers and thunderstorms to the area on Thursday, especially during the afternoon hours. There is a possibility that the weather on Wednesday could make the storms form farther to the south on Thursday, we'll just have to wait and see on that part. By Friday, all of the shower activity will have moved out of the area, and the day is setting up to be nice and dry with mild temperatures.

We'll have a slightly active weather pattern setting back up over the area for Saturday as troughing starts to form and begins to move near the area. This will allow several waves to move through the area, but as of now, rain chances will be small and mainly during the afternoon hours. Same story on Sunday, but rain chances will be even smaller, and I wouldn't be surprised if I will be able to remove those rain chances out of the forecast within the next day or two.

Bottom line: We'll mention the chance of rain on both Saturday and Sunday, but more than likely it will stay dry at the track. I'll have a really good idea by Wednesday night on what the weather will hold for us at Road America.

By Doug Schneider - @Race4caster

Click images to enlarge

Perfect racing weather is expected from start to finish for the 24 Hours of Le Mans. There will barely even be a cloud in the sky. Temperatures will be pretty warm today, and a little warmer tomorrow. The forecast has played out pretty much as I expected since my first forecast last weekend, so there's not much to day other than enjoy the race!

​Here's the astronomical information for Le Mans today (from timeanddate.com):

By Doug Schneider - @Race4caster

Click images to enlarge

The weather continues to look great for the 24 Hours of Le Mans. Surface high pressure will be located near the English Channel Friday through Sunday, while a strong ridge in the mid and upper levels of the atmosphere will be across France. This ridge is trending a little stronger in the latest model runs, which is why I have bumped up the temperatures a few degrees for today's forecast update. With the strong ridge in place, there will be lots of sunshine and no chance of rain for the driver's parade on Friday and throughout race. 

I'll have a more detailed forecast of temperatures through the race on Saturday morning.

By Scott Martin - ​@RaceWx4You

Looking at the latest GFS model trend for this weekend, we'll have moisture in the Central Indiana area throughout each day, but I believe we may be able to squeeze at least two days of racing action without any interruption from Mother Nature. Even though I do have a small chance of rain for Friday, I believe we can make it throughout the day completely dry. The reason for the 20% chance is that models do not handle convective pop-up showers and storms well.

Just about the same can be said for Saturday but had to up the risk a little bit as precipitable water values will be higher, around 1.75 inches. There will be scattered shower and storm development, but I believe those will come later in the afternoon. Crossing my fingers that the on-track activity will be completed by the time those form.

More available moisture will be in the area on Sunday, with precipitable water values up around 2.00 inches. Showers and storms will be able to develop easier with the heating of the day, so there will be scattered to numerous showers around especially during the afternoon hours.

It is still early in the forecast game, but I'll be able to have a better look at what to expect when the higher resolution models come out this week. Radar will be up by Thursday on the site.

By Doug Schneider - @Race4caster

Click images to enlarge

There hasn't been a significant change in my thinking for the forecast for Le Mans, except for a shift in the timing of rain chances from Wednesday to Wednesday night/Thursday morning. The low pressure system that I mentioned in the last forecast post is trending a little slower, which will push the chance of rain more into Wednesday night. There's just a slight (20%) chance of the rain continuing into Thursday morning as the low exits to the east. The amount of rain continues to look very light, and perhaps less than before - just a few hundredths of an inch, or a millimeter or two. So no impacts are expected at the track. 

The rest of the week continues to look dry, sunny, and warm as high pressure builds over the region. It's going to be a great weekend to take in the Le Mans experience. Wish I could be there!

By Doug Schneider - @Race4caster

Click images to enlarge

I'm not sure you could ask for much better weather for Le Mans week than what I'm expecting this year. There is good model agreement in the general weather pattern, so my confidence in this forecast is fairly high, which means I don't expect bug changes to it as we go through the week.

Practice sessions begin on Wednesday, and that could be the only day that has a chance of rain. There is likely to be a low pressure system moving west to east across southern or central France that day. The position of the low will affect how much, if any, rain falls at the track on Wednesday. It may stay far enough south that no rain will fall, but I think there's enough of a chance to include a 30% probability of rain. It does appear that any rain will be light, so any impact on the practice session should be low. Amounts will likely be less than a tenth of an inch, or less than 2.5 mm.

The rest of the week looks dry as surface high pressure will be centered off the west coast of France, providing a north to northwest flow across the country. Thursday may be a little breezy as the high starts to build in behind the low, with a northwest wind at 10-15 mph (16-24 km/h). Sunny skies with a slight warming trend are expected through the rest of the week and into the weekend. Unless there's a major shift in the pattern shown by the models, it's going to be perfect racing weather through all 24 hours. 

Follow me on Twitter and our Racecast Weather social media feeds on the right for weather updates through the week.

By Doug Schneider

The festivities for the 24 Hours of Le Mans begin this Sunday with the traditional scrutineering ceremonies at the Place de la République in the town center of Le Mans. There's always a big crowd on hand, as it provides fans an opportunity to get up close to the cars and drivers in a relaxed setting.

The weather looks good for scrutineering this year. Sunday will have warm temperatures and plenty of sunshine, with highs in the upper 80s F and around 31 C. A cold front is expected to move across the area Sunday night, but with very little moisture to work with, the front is not expected to bring any rain. Even if there were some sprinkles, it would likely be overnight. Temperatures on Monday will be a little cooler behind the front, and winds will shift to the northwest. Early morning clouds will give way to plenty of sunshine by midday.

The long term outlook for the week leading up to the big race looks promising for nice weather. The models are in general agreement that a large high pressure ridge through the lower and mid levels of the atmosphere will be across western Europe through the week and into the race weekend. Here's a depiction of what the pattern is projected to look like near the start time of the race next Saturday from the ECWMF Ensemble Prediction System:

The colors represent heights at the 500 mb pressure level, so the ridge of orange colors over western Europe indicate a high pressure ridge through the midlevels of the atmosphere. The black lines are surface pressure, and we see the center of a high pressure area near Netherlands. This pattern will favor dry conditions and warm temperatures for Le Mans late in the week and the race weekend. Keep in mind that this is a forecast for 240 hours away, so things are likely to change somewhat as we get closer to the race. But so far, all signs point toward nice weather at Le Mans. 

I'll have a forecast graphic for Wednesday through Sunday posted on Sunday, so be sure to check back then.

By Doug Schneider

The weather still looks good overall for IndyCar's visit to Texas Motor Speedway this weekend, but I have added just a slight chance of a storm on Friday with today's forecast update.

In my post on Monday, I mentioned some uncertainty about the rain chances on Friday. That chance looks slightly higher today, due to a little more moisture and instability that could be present, and a weak upper level disturbance. But I still think that it is highly likely (around an 80% chance) that all racing activities will be held without any weather issues on Friday. Saturday continues to look dry, with temperatures during the race from the mid 80s at the start to lower 80s by the finish. There will be a south wind at 10 to 15 mph with gusts near 20 mph, which could create a tricky crosswind in turns 3 and 4.

By Doug Schneider

A fairly typical weather pattern for north Texas is expected this weekend as IndyCar moves to Texas Motor Speedway, which should mean dry conditions with warm temperatures for the end of the week.

On Friday there will be a southerly flow in the low levels, which will bring some moisture off the Gulf of Mexico. However, there will be a ridge in the mid and upper levels of the atmosphere, which should provide stable conditions over north Texas that will suppress thunderstorms. There will be a dryline developing over west Texas in the afternoon, but it does not appear that there will be a lot of storms developing along it, and if they do, they will stay well to the west of TMS. I'm not 100% confident that there won't be an isolated storm on Friday evening, but the chances of rain at the track appear too low to mention right now.

I'm more confident that Saturday will be dry, as the atmosphere looks like it will be drier and more stable than Friday. A dry northwesterly flow in the mid and upper levels will continue, and if storms are able to form on the dryline, they will stay well to the west. 

By Doug Schneider - @Race4caster

The forecast for Detroit this week has been a moving target, but the pattern is starting to come into better focus as we get closer to the weekend. There are still some uncertainties about the timing of rain chances at Belle Isle, but the latest data point toward a better weekend for racing than previously indicated.

Friday looks like a nice day at the track, with mostly sunny skies and highs in the mid 70s. A cold front will be pushing south toward Belle Isle on Friday, but it isn't expected to move across the area until Friday night. The front will have very little moisture to work with, so there may not be any rain with it when it moves through. 

High pressure will be building over the area on Saturday, and the front will be to the south of Detroit, across northern Ohio. Most of the day will be very nice, with mostly sunny skies and highs in the mid 70s. However, as a low pressure system approaches from the west, a southerly flow will develop, spreading greater moisture into the area and pushing the front back to the north. While I think the majority of the rain with this will come after Saturday's racing ends, there is some uncertainty about timing, so I have just a 20% chance of rain late in the day, but with very low impact on the IndyCar race at 3:30 pm. No impact is expected for the Trans Am and IMSA races that will be held earlier in the day.

Showers and thunderstorms are likely on Saturday night into Sunday morning as low pressure track east across Michigan, but the big question is, when will it end? There is a lot of uncertainty about this, but what I can say is that conditions should be improving through the day. The most likely sessions to be impacted by rain will be IndyCar qualifying and Trans Am Race 2. It is possible that there could be enough rain to cause some delays to these sessions, depending on how well water drains off the track.There will still be a chance of rain through the afternoon, but the chance will be lower than in the morning. I'd put the chance of rain in the morning at 60%, but closer to 40% in the afternoon. The Stadium Super Trucks and IndyCar Race 2 will probably have a wet track to deal with, but I don't think the conditions at that time will be bad enough to cause major delays or cancellations.

We'll have our live radar feed going through the weekend - just use the Radar link at the top of the website. I'm going on a beach vacation with my family this weekend, so my weather updates on Twitter will be limited, but Scott (@RaceWx4You) will help to keep you informed of the latest weather conditions at Belle Isle.

The forecast graphics for IMSA and Trans Am (Impact level differs based on the timing of races and expected rainfall):

By Doug Schneider - @Race4caster

There have been some big shifts in how the models depict the weather pattern evolving over Detroit this weekend. I have very low confidence in this forecast, due to the models changing their tune back and forth between dry and wet. With so much uncertainty, I cannot make the forecast very detailed or specific in regard to timing of rain. But based on the latest model runs, it looks like there will be at least a chance of rain at the track each day. I wish I could make a forecast with greater confidence one way or the other, but sometimes we just have to admit that we don't know what will happen.

By Doug Schneider - @Race4caster

The Detroit Grand Prix is always a big event packed with racing action, as IndyCar, IMSA WeatherTech Championship, and the Trans Am Championship will all be racing on the streets of Belle Isle Park. The weather could cause some problems on Friday, but the rest of the weekend is looking good so far.

On Friday, the Detroit area will be in a warm and moist south to southwesterly flow, while a cold front will be pushing south across the upper Great Lakes. In the warm, moist air mass ahead of the front, there will likely be showers and thunderstorms. The question of timing is too uncertain this far out to be very specific, but I think the afternoon will have better rain chances than the morning. At this time, I have the impact on racing as moderate, meaning there will be wet conditions and possibly some delays in the schedule. I could see the impact becoming high with later forecast updates if the rain will be heavy, but that is too uncertain right now.

The cold front will move through Friday night, bringing a drier and cooler air mass to the area from the north. Saturday looks like great racing weather, with mostly sunny skies and highs in the upper 60s.

There is a little uncertainty about Sunday, but I'm going with a dry and mostly sunny forecast. Some previous model runs had shown the cold front lifting  back to the north and bringing more rain on Sunday, but the latest models are in better agreement with each other that the front will remain to the south of Detroit. I'll feel more confident in the dry forecast with additional model runs that continue to show this trend. 

Here are the forecast graphics for the other series that will be in action at Belle Isle:

By Scott Martin - ​@RaceWx4You

The latest model runs are in and I believe that the 101st Running of the Indianapolis 500 will remain dry throughout the entire event. There will be storms during the pre-dawn hours but will be out of the area well before 8AM. The skies will be mostly cloudy throughout the day, but conditions will be favorable for dry weather until around 2PM when a few scattered showers and thunderstorms will begin to develop. I do believe that those will stay west of the track until after the checkered flag falls, but I'm going to leave a 10% chance of a shower reaching the track before the end. It is almost not worth mentioning in the forecast, but this is racing on an oval with slick tires... any moisture could cause a problem. Therefore the 10%. The afternoon high will be around 80 degrees, and winds will be out of the southwest at 5-8 MPH.

Radar is up and running, and you can view it on your smart phone as well. I'm crossing my fingers that the forecast holds up throughout the night. I'll have another update in the AM.

By Scott Martin - ​@RaceWx4You

Believe it or not, I think Mother Nature is going to cooperate with us and allow Legends Day today and the Indianapolis 500 tomorrow to go on without any major delay or disruptions. We will have to deal with strong to possibly severe storms tonight through the overnight hours, but those will be gone in enough time for the big race on Sunday.

TODAY
There should be no problems at all during the day at Indianapolis Motor Speedway as far as the weather is concerned. Skies will be mostly cloudy throughout the day, which will bring a little relief to those who are sensitive to the sun, and the afternoon high will be around 80 degrees. Winds will be light out of the northwest at 1-3 MPH.

As far as tonight is concerned, there is the possibility of some strong to severe storms that could move through the area after 11PM associated with a mesoscale convective system. The Storm Prediction Center has the Indianapolis area in a slight risk for severe storms throughout tonight and into the morning hours on Sunday. The good news is that the storms will be on a weakening trend as they reach Central Indiana, but the threat of damaging winds and hail are still possible. The threat of tornadoes will be rather low, but not zero. Please stay weather aware tonight, especially if you are camping at the speedway.

SUNDAY
The line of storms should diminish around sunrise, and much of the daytime hours should remain dry on Sunday at the speedway. There could be an isolated shower or two pop up during the afternoon hours, but a relatively strong cap will be in place keeping any storms from developing. So I'm thinking optimistically and going with the race starting on time and racing to full distance. Skies will be mostly cloudy throughout the day, and the afternoon high will top out around 79 degrees. Winds will be out of the south-southwest to the west-southwest at 5-10 MPH. If a shower pops up and moves over the track, it should not last long and the rain amount will be light. The chance for rain at the track is 20%.

Most of the models are agreeing and keeping Indianapolis dry throughout the day, but the GFS is keeping moisture around. Normally the GFS model is not the best at guessing convective activity, so I'm sticking with the NAM-3k mainly for the forecast. I'm crossing my fingers that I am right.

By Scott Martin - ​@RaceWx4You

I think today is going to be a great day in Indianapolis, Looking at the latest HRRR, rain stays away from the area throughout the day, but storms look to move into the area around or just after 7PM tonight and will be quick out of the area around or just after 2AM Saturday morning. There is a potential for these storms to be strong to severe, and the Storm Prediction Center has a marginal risk for severe storms up for the area throughout the day until 8AM Saturday. If you're out and about, or if you're camping out, keep weather aware. For during the daytime hours at the track, there will be no problems. Skies will be mostly sunny, and the high will be around 79 degrees. Winds will be out of the south at 3-6 MPH.

Saturday is going to turn out to be another great day at the track, as skies will be partly to mostly cloudy throughout the day. The afternoon high will be around 79 degrees. Winds will be out of the north-northwest at 2-5 MPH. For the night time hours, there is a slight risk for severe storms in the Indianapolis area, mainly for another line of storms that is expected to move through during the overnight hours around or just after 1AM. The main threats will be from damaging winds and large hail, and there is a possibility for a few tornadoes as well. The latest NAM-3k model run is keeping the storms just south of Indianapolis, but not far enough to be comfortable to say there is no risk. Once again, stay weather aware, especially if you're camping out.

I may have some good news for Sunday for the Indianapolis 500. The latest run of the NAM-3k is keeping the main bulk of the rain and storm activity well to the south of Indianapolis. There will be another wave of storms that will be approaching the area, but it looks like it won't reach the area until well after the race is over. Now I am not ruling out a scattered shower or a brief thunderstorm to move over the track during the day, but as of now, it doesn't look all that bad. So my official forecast would be: Storms ending before 8AM, then skies will be mostly cloudy throughout the day. A passing shower or thunderstorm is possible during the day, but the likelihood of that is small at this point. The afternoon high is expected to be around 77 degrees, and the winds will be out of the south at 5-8 MPH. Chance of rain from 10AM-4PM will be around 20%.

Radar is up and running on the site, so feel free to use it at anytime. It refreshes every 60 seconds, so it will update the latest radar image in from the NWS Indianapolis as soon as it is uploaded. I'll have more updates throughout the weekend, especially on Sunday if rain develops around the track area.

By Doug Schneider - @Race4caster

Light rain has been around Lime Rock Park today, with around two tenths of an inch recorded at a nearby rain gauge. An upper level low pressure system is located to the west today, and will track east overnight. It will be positioned near Boston by Friday morning.

Some moisture will continue to wrap around the counter-clockwise circulation of the low into Friday, which will keep a good chance of showers in the forecast as cars hit the track. The good news is that any rain on Friday is expected to be light. It may only be on/off sprinkles. The total amount of rain on Friday will likely be under a tenth of an inch, so I expect that the impact on racing will be low. Some wet tires will probably have to be used at some point, probably for the morning sessions, but I don't foresee significant weather delays or cancellations. If you're attending the race, you may want to bring an umbrella. With a northwest wind and cloudy skies, temperatures will be pretty cool all day, mainly in the 50s.

Saturday looks like a great day to be at the track, and any chance of rain will end as the low moves farther away. Pleasant temperatures in the upper 60s are expected, with sunshine peeking through the clouds at times. 

By Scott Martin - ​@RaceWx4You

FRIDAY
The good news is that I have removed any rain chances out of the forecast for the Carb Day Festivities and the running of the Freedom 100. Skies will be mostly cloudy and the high will top out around 78 degrees. Winds will be out of the south at 3-7 MPH. Storms will move in for the evening, but well after the Steve Miller Band completes their show.

SATURDAY
Storms from the overnight and pre-dawn hours should be coming to a end before 8AM when the gates open at the track. Skies will be mostly cloudy throughout the day, as there will be a break throughout the morning into the early afternoon hours. Shower and storm chances begin to rise after 2PM, but just slightly. Good news is that the main bulk of the storms will move in after 8PM, well after the track closes for the day. The afternoon high will top out around 80 degrees, and winds will be out of the south to southwest at 3-8 MPH. The chance of rain throughout the day at the track is 30%.

SUNDAY
Here is where we may have some gnashing of teeth due to the weather. Looking at the latest model runs of the NAM and the GFS, there will be moderate to heavy rain/storms throughout the morning hours until 7-8AM. Then there will be a dry slot that opens of for Central Indiana from then until at least 2PM on both models (NAM-left, GFS-right), and the GFS keeps it dry until 8PM. So according to these model runs, the track should be dry for the scheduled race time. Double-checking with the NWS Indianapolis office, there are keeping the rain chances in throughout the day. Even though the amounts will be light, there is a possibility of a few delays. I'm going to side with the NWS right now until I can see when the high-resolution models come in to play. Skies will be mostly cloudy, and there will be a chance of rain throughout the day. The high will top out around 77 degrees, with winds out of the west to northwest at 5-7 MPH. Chance of rain as of now will be at 50%.

Once the timeframe for the high-resolution models come in to play, I can only cross my fingers and hope that the GFS and NAM models are correct. I will be able to nail the forecast down within 24 hours. Radar is up and running, so please feel free to use it and stay up to date with where the rain is happening.

By Scott Martin - ​@RaceWx4You

This weekend at the Indianapolis Motor Speedway for the 101st running of the Indy 500 is starting to get that "iffy" look to it. There will be a system moving through the area starting on Friday evening and will not leave until the late afternoon hours on Sunday. We should be able to get the race in on Sunday at full completion, but will we have some delays? That is the main question. Here is the forecast as of now...

Friday
The day will start off with mostly clear skies, but clouds will be on the increase during the day. It will be dry during the morning and early afternoon hours, but the chances of an afternoon shower/storm rises to about 1 in 5 for the remainder of the daytime hours due to the approach of an upper wave. Good news is that if any rain occurs, the amounts will be very light, and delays will be short if any at all. Afternoon high will be around 76 degrees, and winds will be out of the southwest to the south at 3-6 MPH.

Saturday
That upper wave will have the possibility of bringing some strong storms to the area during the evening on Friday into the day on Saturday. An unstable airmass with the wave will allow for robust convection, and the highest threat for strong to severe storms will be across Central Indiana. There will be a wave of storms moving through before 8AM, then a lull in the action until the mid afternoon hours, and scattered storm development picks back up throughout the rest of the day. Too early to know what the strength or what threats will be, but Saturday needs to be a day to stay weather aware. The high will top out around 80 degrees. Rain chances are over 50% to start with, then drop to around 20% during the lull in action, and finish off near 50% for the late afternoon into the night time hours. Rain totals of 1/2 inch will be possible.

Sunday
As the wave moves through the area, rain and storm chances will begin to drop throughout the day. Skies will start off mostly cloudy, but will begin to clear out some as the afternoon progresses. The high should top out around 76 degrees, with winds out of the west-southwest at 5-10 MPH. Rain chances start off at 40% during the morning, and drops to around 30% by noon. Good news is that if any rain occurs, the amounts will be very light, and delays will be short if any at all.

By Scott Martin - ​@RaceWx4You

Looking at the forecast ahead for the weekend's events at the Indianapolis Motor Speedway, I really do think that much of the on-track activity, if not all, will remain dry. We may have a few showers after the Freedom 100 on Friday and after the Indy 500 on Sunday, but Saturday will probably be a day featuring a few passing showers affecting the area throughout the day and into the evening. Here are the details...

Friday
Latest GFS model run remains dry for much of the day, but a brief shower is possible after 2PM. Otherwise skies will be mostly sunny, with the afternoon highs in the upper 70s, around 77. Winds will be shifting from the west to the southwest by the late afternoon, averaging around 5 MPH. Chance of rain is really low during the afternoon, at 20%.

Saturday
There is a small chance for rain during the morning and early afternoon hours, then increasing during the late afternoon and evening hours. It will be a mostly cloudy day, and highs will be in the upper 70s to near 80 degrees, going for 79 degrees at this point. Winds will be out of the south to southwest around 5 MPH. Rain chances before 2PM will be around 10%, but increasing to 30% after.

Raceday
It will be a day that features a mix of sun and clouds, and there is a very small chance of a shower or storm during the day. Rain chances during the race will be around 20%, and will rise to 30% after 2PM if the race goes into that hour. I have a strong feeling at this point that the race will be dry. Afternoon highs will be in the upper 70s, near 78 degrees. Winds will mainly be out of the west at 5-8 MPH.

By Doug Schneider - @Race4caster

An unsettled weather pattern this week across the northeastern states will bring some rain to Lime Rock Park for Thursday and Friday, but conditions will be improving for race day. 

As teams load into the track on Thursday, low pressure over Ohio will pump moist air into New England. This moist air will ride up and over a warm front that will be located near Long Island, and will likely produce a good amount of rain at the track. Thursday definitely looks like the wettest of the three days. 

The center of the surface low pressure will track across northeast Connecticut Friday morning, continuing to Boston and off the coast of Maine by the evening. This will take the bulk of the heavier rain east of the track, but there will still be moisture wrapping around the upper level trough and a little instability that will keep a chance of showers in the area. I think the greatest coverage of showers will be on Friday morning, with less coverage through the afternoon. But right now, I'm not entirely confident with how fast this system will move east, so there could be scattered showers around all day. I do not expect that there will be heavy rain that will cause cancellations or major delays like we saw at CTMP - more of a light on/off rain rather than a steady moderate/heavy rain - so I have the impact on Friday as low.

Saturday will be the best day of the event as the low moves away and high pressure builds in. With partly cloudy skies and temperatures around 70 degrees, it looks just about perfect for racing. 

In the forecast graphic, I have chosen a picture of Andrew Palmer's car from last year at Lime Rock Park as a reminder that he is still recovering from injuries sustained in a terrible crash at the track last year. Please keep Andrew and his family in your prayers.

By Doug Schneider - @Race4caster

A cold front has moved through southern Ontario, bringing much cooler temperatures today. The cool temperatures will continue through Saturday as high pressure moves east across Ontario and Quebec, as highs will be near 60. There will be more sunshine on Saturday compared to today, but clouds will start to increase again in the afternoon ahead of the next system. 

There hasn't been much change in the expected weather for Sunday. There is still a very high chance of seeing rain at the track, and I expect that rain amounts all day will be between 0.2 and 0.5 inches. This could be enough to cause some delays to the action at times. There is still some disagreement in the models regarding the timing of rain, but the chance of rain will likely be rising through the morning, peaking around midday, and falling through the afternoon. I don't think the day will be a total washout though. The wet conditions will make for some interesting racing.

By Doug Schneider - @Race4caster

Overall, there hasn't been too much change in my thinking for the weather forecast at CTMP this weekend. There's going to be beautiful weather on Friday and Saturday, but Sunday continues to look pretty wet. 

A low pressure system will pull a cold front across southern Ontario on Thursday night, and there could be some scattered showers and thunderstorms ahead of it. The most likely timing for any chance of rain appears to be in the late afternoon and evening hours, so a vast majority of the day will stay dry with warm temperatures. I only have a 30% chance of rain before track activities end at 6:20 pm. There will be a higher chance of rain after that time when the front moves through.

Friday will be breezy and cooler as high pressure builds into the area behind the cold front. It will be mostly sunny, but temperatures will only reach the lower 60s (upper teens Celsius). Saturday will also be quite nice, with less wind and slightly warmer temperatures. Clouds will be increasing through the day ahead of the next low pressure system. 

The cold front that moved through on Thursday night will lift back to the north to near Lake Ontario on Saturday night, and as the center of the low pressure system moves across Michigan, a moist southerly flow up and over this warm front will result in a wet day on Sunday. I have high confidence that there will be rain on Sunday, so I have raised the chance of rain to 80%. The most likely amount of rain at the track on Sunday appears to be between 0.2 and 0.5 inches, or between 5 and 13 mm. Periods of rain are possible at any time of the day, so I think that all action on the track will be affected. This could result in some delays or possibly cancellations of events, depending on how heavy the rain will be.

I plan on having another forecast update posted on Friday, unless there is a major change before then.

By Scott Martin - ​@RaceWx4You

With ridging in control of Central Indiana's weather, Wednesday at Indianapolis Motor Speedway will be mostly sunny but quite breezy at times. Winds will be averaging between 15-25 MPH out of the south-southwest, but gusts up to 35 to near 40 MPH are possible. Temperatures will be in the upper 70s at 10AM when the gates open, and the high will be around 86 degrees in the afternoon.

An approaching front is expected to stall out in or near the southern part of the state, and this will bring a slight chance of a shower or thunderstorm during the morning through the early afternoon hours. The front may creep ever-so-slowly southward reducing the rain chances for the remainder of the on-track time. Expect a mix of sun and clouds, with winds continuing to be breezy out of the southwest at 10-15 MPH with gust up to 25 MPH possible at times. 10AM temps will be in the lower 70s, and the high will top out around 82 degrees. Chance of rain before 2PM is 30%.

The stalled front will be forced northward during the day on Friday, bringing an increased chance of showers and storms especially during the late afternoon. It will be a mostly cloudy day with much calmer winds starting off out of the northeast and shifting to out of the east-southeast by late afternoon. Temperatures start off in the upper 60s at 10AM, and warming to near 78 for the high. Rain chances are low before 2PM, around 20%, but increase after that to 50%.

A low pressure center will be moving across the upper midwest on Saturday continuing to force the ever-so-slow moving front northward across Central Indiana on Saturday, and will drag a trailing cold front across the area on Sunday. Shower and storm chances appear to be likely throughout the day on Saturday, with rain totals of 1/2 inch possible. Not saying that Saturday is going to be a complete washout, but on-track activities may be halted a few times. Sunday's rain chances are a little lower for "Pole Day," but only slightly. Another day that will have stoppages, but not a complete washout. Saturday's high will be around 81, with Sunday's high cooler, around 75.

By Doug Schneider - @Race4caster

The weather at Canadian Tire Motorsports Park this weekend will be affected by a couple of low pressure systems and frontal passages, making for a weekend of varied weather.

The first low pressure system will move across the upper Great Lakes and central Ontario on Thursday, This will bring scattered showers to the area around the track through the day. There will also be a good southwest wind at 10 to 20 mph all day, which will help temperatures warm up into the 70s. 

The cold front associated with the low will cross the area and settle to the south on Thursday night, which will bring an end to the rain chances and usher in some cooler and drier. air. Friday looks like a beautiful day at the track, with a high in the upper 60s and mostly sunny skies. Winds will shift to the north behind the front, and it will still be breezy.

Saturday should continue to have nice weather as high pressure moves east across Ontario, with some increasing clouds ahead of the next low pressure system. It looks like any chance of rain will hold off until after dark.

Sunday isn't looking good right now. For the past few days, the models have been showing a low pressure system that will track east across the Great Lakes during the day. As a result, the front that moved through on Thursday night will lift back to the north as a warm front, which will produce a high chance of rain on Sunday. The models are in pretty good agreement with this scenario, so I have a 70% rain chance on Sunday. There is a good southwesterly flow of moisture up and over this warm front, so it appears that rain amounts could be pretty high, with heavy rainfall possible at times. This is why I have a high impact on Sunday - if the current models hold up, I could see some significant delays or cancellations to the races.

​I'll have a better idea of potential rain amounts in the next few days, so stay tuned for updates.

By Scott Martin - ​@RaceWx4You

Now we've got the wet stuff out of here, let's get some sun and warmer temperatures into Indianapolis for the Indycar Grand Prix.

FRIDAY
Skies will start off mostly cloudy at the 8AM hour, with temperatures at or around 50 degrees. As the day progresses, the clouds will begin to thin out and skies will be mostly clear by the end of the afternoon. The winds will be out of the north-northeast at 6-11 MPH, and will be at their strongest point during the mid to late afternoon hours. Afternoon highs will be in the upper 60s, topping out around 68 degrees.

SATURDAY
Race day for the Verizon Indycar Series will be a much brighter and warmer day at Indianapolis Motor Speedway. Skies will be start off mostly sunny and remain that way throughout the day, even though a few more clouds will develop with the heating of the day. Temperatures will start off around 49 degrees at the 8AM hour, and rise into the lower 70s by the afternoon, around 73 degrees. Winds will start off out of the north-northwest at 2-9 MPH, but will be turning out of the west by the end of the afternoon hours.