By Scott Martin - ​@RaceWx4You

Looking at the latest forecast models for the Austin area throughout the weekend show that an approaching trough with an associated cold front will be making its way toward the area on Friday and Saturday. With that, along with high pressure and ridging to the east, this is allowing warm and moist gulf air to flow in from the southeast. Skies will be mostly cloudy, and as the trough gets closer, we will have a chance of isolated showers and thunderstorms on Friday and during the day on Saturday. Highs on both of these days will be in the lower 80s (27-28ºC). Winds will be out of the east-southeast around 5 MPH (8 KPH) on Friday, and out of the south at  5-10 MPH (8-16 KPH) on Saturday.

The trough arrives with the cold front on Saturday evening and will work its way through during the first half of Sunday. This will bring a decent chance of showers and thunderstorms for Saturday night through a good part of the daytime hours on Sunday. Unfortunately, rain chances at this time doesn’t appear to drop off until after 5:00 PM (2200 UTC). Winds will be quite breezy and cool as they will shift from the west to out of the north by the afternoon hours, averaging between 5-15 MPH (8-24 KPH) with gusts up to 20 MPH (32 KPH) possible. Rainfall amounts of 1/2 inch to 3/4 inch (12.7mm-19mm) are possible, and rain tires are almost a sure bet. Afternoon highs will be much cooler only reaching the upper 70s (24-25ºC).

Lightning may be an issue with any rain throughout the weekend, so please seek shelter if you hear thunder. The saying is “if you hear thunder, you are close enough to be struck by lightning.” So when thunder roars, go indoors. Radar will be up and running on our website starting on Friday and will be up throughout the weekend. Please feel free to share any of this information with friends or relatives that are headed out to COTA for the event.

By Scott Martin - ​@RaceWx4You

As I mentioned in the first forecast for the event weekend out at Mazda Raceway Laguna Seca, an upper-level ridge would be moving into the area during the weekend bringing with it warmer temperatures. Model trends have come in stronger with the ridging and therefore temperatures will be allowed to rise several degrees above normal for mid-October, especially on Sunday. As for today, cooler weather will stick around before the ridge takes hold on Saturday. Unfortunately with the higher temperatures, the fire risk will continue to be high. Our thoughts and prayers go out to those who have been affected by the fires and to the ones who have lost loved ones. Radar will be up and running today as well... unfortunately, it will not be needed.

By Doug Schneider - @Race4caster

The outlook for the Six Hours of Fuji hasn't changed much in the past few days. It still looks like a very wet weekend as a front is expected to stall near the southern coastline of Japan. The one bright spot in this forecast update is that the impact of the rain on Saturday looks less than it did before. 

Today, radar shows that a solid line of showers will move across Fuji Speedway, associated with a cold front. As the front moves southeast, it will stall near the southern coast of Japan, just south of the track. Warm, moist air riding up and over the front will keep periods of rain going through Saturday and Sunday. The flow of moisture over the front appears to be weaker than it did a few days ago, so I have lowered the forecast rainfall amounts on Saturday, and dropped the Impact back to Moderate. This means that all planned on-track activity should be able to be completed, but probably not without some delays or at least the use of rain tires.

The pattern doesn't change much for Sunday, and periods of rain will continue to affect the racing action. Rainfall amounts look higher on Sunday than Saturday, with up to a half inch (13 mm) expected through the day. I think it will be a steady light to moderate rain, rather than a heavy rain that will cause the race to be stopped. Thus, I have the Impact as Moderate. With the surface front located to the south, temperatures will be cool all weekend.

By Scott Martin - ​@RaceWx4You

The forecast for racing at Mazda Raceway Laguna Seca looks great, but the overall forecast for the fire conditions continue to not look that good. Gusty winds and very low dewpoint values will unfortunately keep the risk of wildfires high. Our thoughts and prayers go out to those who have been affected, and to the crew battling the fires.

The forecast throughout the weekend can't really be any better for racing. Cooler temperatures will make it better for the drivers, but those same temperatures will warrant the need for jackets at multiple times throughout the event. The only concern that we may have is smoke from the nearby fires.

Friday will be a rather cool and quite breezy day, with winds starting out of the northeast and shifting out of the northwest at 5-15 MPH with gusts up to 20 MPH likely. According to how strong the system that will be moving into Nevada, we may have to increase those winds speeds.

Ridging will start to build in for Saturday and Sunday, bringing warmer daytime highs and lighter winds. Conditions will remain really dry throughout the weekend, and those jackets will be needed for the mornings. Highs on Saturday will be in the lower 70s, with upper 70s expected for Sunday.

Radar will be up and running starting on Friday morning, but it will not be needed.

By Doug Schneider - @Race4caster

The forecast for the Six Hours of Fuji weekend isn't a question of whether it will rain or not - it's going to rain, but how much will fall and how the racing will be impacted by it are the questions that remain to be answered. 

The weather pattern across the region will be a front pushing toward the southeast across the Sea of Japan on Friday, which will stall across the southern half of Japan on Saturday. A southerly flow of moist air above the surface will ride up and over the front, which will make for a very wet day on Saturday. An upper level trough will also be approaching from the west on Saturday, further enhancing the rain that day. But that trough is expected to help push that front a little further to the south on Sunday, which could mean less rainfall on race day.

There is good model agreement about this general pattern, so I'm confident that there will be rain, especially on Saturday, but the details of how much rain might fall is still uncertain. Saturday will likely have the greatest rainfall amounts, which is why I have the Impact as High that day. Friday and Sunday may have less rain, so I have a Low to Moderate Impact rating for those days. My best estimate of rain amounts on Friday and Sunday is between 0.1 and 0.3 inches (3-8 mm) each day, and between 0.5 and 1 inch on Saturday (13-25 mm). The exact position of where the front will be located each day will have a big impact on how much rain falls at the track. This far out in the forecast, it's nearly impossible to predict exactly where it will be. 

With a lot of cloud cover the entire weekend, and a north wind behind the front on Saturday and Sunday, temperatures will be quite cool, with highs only in the upper 50s to lower 60s (mid to upper teens Celsius). 

Follow me on Twitter for forecast updates through the week - @Race4caster. I'll have the next update by Friday at the latest, unless there are big changes needed before then.

By Doug Schneider - @Race4caster

fThe impact of Tropical Storm Nate on Road Atlanta will be indirect, as the system is expected to only be making landfall near New Orleans on Saturday night. So the track won't be affected by its outer rain bands or by its winds. Instead, the southeasterly flow of winds across Georgia well ahead of Nate will transport a good amount of moisture from the Gulf of Mexico and Atlantic Ocean on Saturday and Saturday night, while a warm front across South Carolina and central Georgia moves north. The good news is that the heaviest rain associated with the outer rain bands of Nate are not likely to reach the track until Sunday. 

Saturday will likely have a good amount of cloud cover all day, and it is possible that a few sprinkles could occur as early as the morning hours. But I think that any chance of measurable rainfall (at least 0.01 inches) will hold off until the afternoon. I expect that some scattered showers and thunderstorms will be around north Georgia in the afternoon, and the chance of one hitting the track is about 30%. With a lot of cloud cover expected, highs will only reach the mid 70s.

After sunset, the chance of rain showers will start to increase as that warm front gets closer and the flow of moisture up and over the front picks up. Sunset is around 7:15 pm, and from that time to the end of the race festivities around 11 pm, I would put the chance of rain at 50%. It does not look like heavy rain, more of a light rain that might pick up to a moderate rainfall at times. If rain occurs during the race, I expect amounts to be just a tenth of an inch or less. Thus, I have the impact on the race as low, meaning that the race should be able to continue through the rain (unlike 2015). However, rain chances will continue to rise overnight (70%), with an additional 0.1 to 0.3 inches possible. This will make for some messy conditions for campers at the track.

​Rain is expected pretty much all day Sunday, and may be heavy at times. Rain amounts on Sunday are expected to be between a half inch and one inch.

I'll be providing weather updates through the race on my Twitter feed - @Race4caster.

By Doug Schneider

Tropical depression 16 is expected to become Tropical Storm Nate as it moves into the Gulf of Mexico this weekend. The forecast for Saturday and Saturday night will depend on the path and speed of Nate, and how much moisture spreads north ahead of it. What does seem likely at this time is that the bulk of the rain with Nate will hold off until after the race ends - mostly late Saturday night and Sunday. The greatest uncertainty is when the rain will start. There is a slight chance of rain arriving at the track during the day on Saturday, but this rain will likely be light. Rain showers will become more numerous and heavier during the night. 

This does not look like the 2015 race that had to be stopped due to heavy rain. I can see the final 3-4 hours of the race being affected by some on/off light to moderate rain showers. The main impact may be on the campers Saturday night as the rain gets heavier. Rain amounts overnight are expected to be in the quarter to half inch range, with additional rain on Sunday. If you're camping at the track, be prepared with some wet weather gear.

I'll have another forecast update on Friday at the latest, and earlier if there are significant changes to this thinking.

By Doug Schneider - @Race4caster

By Doug Schneider - @Race4caster

The weather pattern for late this week is shaping up to provide spectacular conditions for the events at Road Atlanta. Much of the southeast U.S. has been quite dry for the past few weeks, and it looks like this dry and warm pattern will continue through this week.

A large high pressure ridge will be over the area Wednesday and Thursday, and although this ridge will get suppressed to the south on Friday, any disturbances in the flow should remain well to the north of Georgia. The flow turns to the south on Saturday, which may bring a little more cloud cover during the race, but not enough moisture to warrant any mention of rain. However, there may be a possibility of light rain on Sunday as moisture continues to increase. 

Follow our social media feeds on the right for updates on the forecast through the week.

By Scott Martin - ​@RaceWx4You

While the forecast graphic is only for the days with the national championship runoffs, I'm also going to give the forecast for Wednesday and Thursday at Indianapolis Motor Speedway.

WEDNESDAY
Skies will start off partly cloudy this morning with clouds increasing as we head toward the noon hour. There is a very small chance of an isolated shower or thunderstorm during the very early afternoon hours, around 20%. After that, skies will begin the clearing process and should be dry for the remainder of the day. It will be warm today, with the high reaching at or just above 80 degrees. Winds will be out of the north-northwest at 5-10 MPH.

THURSDAY
No rain expected for Thursday, and for the rest of the weekend at Indy. We'll have mainly sunny skies throughout the day with temperatures starting off in the lower 50s at 7:00 AM, and warming into the lower 70s for the high (around 72 degrees). Winds will be out of the north at 4-8 MPH.

FRIDAY-SUNDAY
As the forecast graphic shows, we can expect nearly perfect conditions for racing this weekend at Indy. Skies will be mostly clear each day, with highs running in the 69-73 degree range. You will need a jacket for the morning sessions as temperatures will be starting off in the upper 40s to the lower 50s at 7:00 AM each day. You will definitely need the shades, hats, and sunscreen. No umbrellas needed after today, unless you're using one for a little shade.

By Scott Martin - ​@RaceWx4You

These are always the best forecasts to do for any races... all you have to do is make slight adjustments to the wind and temperatures. Not much I can say here... cool temperatures during the morning hours where you will need a jacket and some coffee or hot cocoa, but those temperatures will warm nicely for the afternoon hours. Winds will be a little breezy at times, but the good news is that there is no rain at all in this forecast.

By Scott Martin - ​@RaceWx4You

By Doug Schneider - @Race4caster

It will be a great weekend to head to beautiful Virginia International Raceway to take in some awesome race cars. Trans Am will have a shared weekend with SVRA's Heacock Classic Gold Cup Historic Races, and the schedule is jam packed with action. A large area of high pressure will be stationary over the Great Lakes and Mid Atlantic region, and it will keep dry and sunny weather across Virginia later this week. Temperatures will be pretty warm too under the high pressure ridge, between 4 and 8 degrees above normal for late September in southern Virginia. There's good agreement among the models on this pattern, so I don't expect that there will be many changes needed to this forecast through the week. Check our social media feeds on the right for updates.

By Scott Martin - ​@RaceWx4You

Click on images to enlarge.

By Doug Schneider - @Race4caster

The main weather story for the Six Hours of COTA late this week will be the heat. A large high pressure ridge through the mid and upper levels of the atmosphere will be sitting over Texas, resulting in mostly sunny skies each day and high temperatures reaching well into the 90s (mid 30s C). These temperatures are 3-5 degrees warmer than normal for Austin this time of year. Everyone at the track will need to take precautions to beat the heat - drink plenty of water, take frequent breaks in the shade or in a air conditioned building, and use sunscreen. 

By Scott Martin - ​@RaceWx4You

It's a championship-quality forecast for the final weekend of the season for the Verizon Indycar Series, as they visit the majestic Sonoma Raceway. Mornings will start off cool each day, but maximum sunshine will allow the temperatures to climb nicely to near 80 degrees each day. Wind will not be an issue for Friday and Saturday, but will be picking up to 10 MPH by Sunday afternoon. We won't even mention rain in this forecast.

By Doug Schneider - @Race4caster

By Doug Schneider - @Race4caster

The SVRA and Trans Am event at Watkins Glen will start off with some wet weather, but conditions will be improving over the weekend.

There will be a large upper level trough across the area on Thursday and Friday, which will produce cloudy and cool weather with scattered showers. Thunderstorms do not appear to be a threat at the track, and at this time I do not expect that the rain on Friday will be very heavy. It looks like there will be mainly light showers that are on and off at times through the day, perhaps occurring with more frequency in the afternoon than the morning.

The chance of rain will continue Friday night, but I expect that the trough will be moving fast enough that the chance of rain will end before the TA2 race on Saturday morning at 10:55 am. This is one part of the forecast that I'm not very confident about right now - it is possible that a few showers could linger into Saturday morning, but I'm going with a dry day for now because I don't think it will have an impact while there is action on the track. Clouds will be decreasing through the day, with mostly sunny skies developing in the afternoon. Despite the sunshine, a north wind will keep temperatures cool, with highs in the mid 60s. 

Sunday looks great as a strong high pressure ridge builds into the area. While morning temperatures will be quite cool, in the 40s, sunny skies will bring temperatures up to the upper 60s in the afternoon. 

By Scott Martin - ​@RaceWx4You

For much of the week I thought that the remnants of Harvey would be swept out of here before the race weekend at Watkins Glen for the Verizon Indycar Series, but the forecast has changed drastically today.

Saturday will not be too bad at the track with partly cloudy skies throughout much of the day. Morning temperatures will start off pretty chilly and may bring a slight delay to morning on-track activities, but it will warm quickly into the mid 60s for the high. There is a very slight chance of a shower passing over the track after the noon hour, but the better rain chance will come during the late afternoon and early evening hours.

Sunday will be a pretty soggy day for the track, especially during the morning and into the early afternoon hours. It will be quite breezy at times as well, as the surface low formerly known as Harvey, passes nearby to the track. We do not expect any severe weather or lightning at this time, but definitely keep posted to the weather conditions through the day. Rain coverage should diminish for the mid-afternoon through the early evening hours, and maybe we can get a dry track for a little while. Afternoon highs will top out in the upper 60s.

By Scott Martin - ​@RaceWx4You

It now looks like the remnants of Harvey will be pushed away from the area before it has a chance to rain on the Indycar weekend at Watkins Glen. Therefore, nice weather can be expected throughout the weekend. Mostly sunny to sunny skies can be expected each day, with highs starting off in the mid-60s on Friday and warming into the upper 70s by Sunday. No rainfall is expected on any day, so Firestone can keep those rain tires in the hauler.

By Doug Schneider - @Race4caster

There hasn't been a big change in what I'm thinking the weather will be in Mexico City this weekend for the WEC event, but my confidence is rising that the racing will be impacted by rain each day. A low pressure system will be taking shape in the Gulf of Mexico, just off the east coast of Mexico. This will produce an easterly flow through the low and mid levels of the atmosphere that will pump moisture toward the track all weekend, but especially Saturday and Sunday. With mountains all around the city, the moisture rising up the mountains slopes will produce showers and thunderstorms each day, and mainly in the afternoon hours. I've raised the chance of rain with the forecast update to reflect my higher confidence, and I've raised the Impact to High, as I think there's a good chance of the rain being heavy enough at times to require a stoppage in the action. Rain amounts are likely to be between a quarter and a half inch each day, but amounts could be higher than that if a storm moves directly over the track. 

The Weather Channel has a pretty good interactive radar display for Mexico here -
​ ​https://weather.com/weather/radar/interactive/l/19.43,-99.13

By Doug Schneider - @Race4caster

The remnants of Hurricane Harvey will be pulling out of Texas by Thursday, and high pressure will build over the state behind it. The high pressure system will bring drier and and stable conditions. This should provide nice weather for Pirelli World Challenge at COTA this weekend. Temperatures will be close to normal for Austin this time of year, with highs in the lower 90s and lows around 70. With a lot of sunshine each day and very little shade at the track, it will be important to stay hydrated and to use sunscreen. 

As the high pressure system over the Plains shifts to the east near the Mississippi River on Sunday, winds near and just above the surface will shift to a more easterly direction. This will transport a little more moisture inland on Sunday, which is why I have a slight chance of showers and thunderstorms in the forecast. I think that most of the activity will stay closer to the Texas coast, well east of COTA, but there is some uncertainty about how far inland storms may develop this far out in the forecast. There is just a very low chance that the racing could be impacted by storms. I'll be keeping an eye on this through the week, so check back here for updates and follow me on Twitter - @Race4caster.

By Doug Schneider - @Race4caster

It looks like the WEC weekend in Mexico City could be a wet one, as there's a good chance of showers and thunderstorms each day at the track. The weather pattern doesn't change very much through the weekend, as there will be a good amount of moisture in the atmosphere. There may be a slightly better chance of rain on Saturday as a low pressure system in the midlevels of the atmosphere develops, producing an stronger easterly flow of moist air off the Gulf of Mexico. But for the most part, the showers and storms will be driven by afternoon instability. It is possible that a heavy shower could stop racing action, but rain amounts are too uncertain this far out to put the Impact rating any higher than Moderate. 

I'll keep an eye on how the models change as we get closer to the event, and I'll post an update when any changes are needed.

By Scott Martin - ​@RaceWx4You

By Scott Martin - ​@RaceWx4You

Not much change in the forecast for the Bommarito Automotive Group 500 at Gateway Motorsports Park...

FRIDAY
Great weather throughout the afternoon hours, with mostly sunny skies and highs in the lower 80s. That is how it will be for the first practice session at 4PM. Qualifying temperatures will be down in the mid to upper 70s, and final practice temperatures at 9PM will be in the lower 70s and dropping into the upper 60s by the end of the session.

SATURDAY
Almost a near repeat of Friday's weather... Sunny skies throughout the day with temperatures topping out in the lower 80s. Temperatures will be dropping down into the mid 70s by the start of the main event at 8PM, and down into the lower 70s by the end of the race around the 10PM hour.