By Doug Schneider

A cold front is expected to move across the Daytona area and bring showers to the Speedway on Friday and Friday night, but the good news is that the timing of most of the rain should allow for very little impact on the on-track activities. 

The Roar will open with warm temperatures and a good southwest breeze on Friday. Through the day, clouds will be increasing as a deep upper level trough and its associated cold front move across the Plains to the eastern United States. Ahead of this front, some scattered showers may develop around Daytona on Friday afternoon. I expect that only the late day practice session will have a chance of rain, and any rain that occurs will likely be light. The main band of showers with the cold front is not expected to move across Daytona until after dark on Friday night. 

By the start of practice on Saturday morning, the cold front should be east of the Speedway, and clouds will gradually be clearing out. The track may be wet in the morning, but it should dry out quickly with clearing skies and a bit of wind. Temperatures will be cooler compared to Friday, but still quite pleasant in the lower 70s. Winds will shift to the west and still be a little breezy at 10 to 15 mph. 

High pressure building over the area will bring a northwest winds and cooler temperatures for Sunday, with morning lows in the upper 40s and afternoon highs in the mid 60s. Still, there will be plenty of sunshine all day, along with low humidity. 

Over the past few days, the models have been in pretty good agreement on this pattern, and have not changed much from run to run, so my confidence in this forecast panning out is fairly high. Check back through the week for updates.

By Doug Schneider

Each year at Racecast Weather, we collect photos through the year of our two favorite things - weather and race cars - and pick the best to be featured in a final post to close out the year. Thanks to the extremely talented photographers (and not so talented, like myself) who took these photos - credit for each pops up when you hover over each image. Click on each image to view a larger size.

Thanks for following our forecasts through 2019, and Scott, Stephen, and I hope you have a very happy Christmas season. We'll see you again on December 30 with the forecast for the Roar Before the 24 in January.

By Doug Schneider

There's no good news to report today about the weather forecast at Thunderhill Raceway this weekend. A deep and slow-moving low pressure system will be crossing Northern California, bringing periods of rain and breezy conditions from Thursday night through Saturday night. The only change change to the forecast worth mentioning is that the models are showing this system moving slightly slower than before, and to account for that, I have added a chance of rain to Sunday morning. So while the vast majority of the 25 Hours will be run in the rain, the final stages of the race, possibly the final 3-6 hours, may be rain-free. Through the event, I expect that rainfall amounts will likely be between 1 and 2 inches. Wind will also be a factor on Friday and Saturday, with sustained winds from the south to southeast at 15 to 25 mph, with gusts between 30 and 40 mph at times. 

By Doug Schneider

I wish I could bring better news of a dry and sunny forecast for the 25 Hours of Thunderhill, but unfortunately, it looks like it will be a very wet weekend in Willows, California. 

A strong low pressure system will be tracking west across the Pacific through the week, and arrive in northern California just in time for the on-track action. As teams set up and start to practice on Thursday, clouds will be increasing but most of the day will remain dry, with just a slight chance of rain possible late in the day. The chance of rain will be increasing Thursday night, and by Friday there will be periods of on/off rain as a flow of deep moisture spreads into the area ahead of the low pressure system. This system will be slow-moving, so rain will continue to spread across the area through Friday night and Saturday. There will also be a good southerly breeze on Friday and Saturday, with sustained winds between 15 and 25 mph, with higher gusts. The total amount of rainfall through Saturday could be between 1 and 2 inches. However, it's still a long way out in the forecast, so the forecast rain amounts will come into better focus as we get closer to the weekend.

Rain is expected to start tapering off on Saturday night. This far out, timing is uncertain, but right now I expect that by daybreak Sunday morning, all the rain should be gone. Clouds will start to decrease as drier air moves in, and there may be a mix of sun and clouds by the checkered flag. 

Check back for updates to the forecast through the week.

By: Stephen McCoy

Springtime conditions are in full swing in South Africa this weekend for the Kyalami 9 Hours. The race weekend will kick off with some lingering showers possible during the early morning on Thursday after showers and thunderstorms are present on Wednesday as an upper level trough moves eastward over the region. As upper level winds return to zonal flow, an area of high pressure is expected to build in at the surface, diminishing chances for precipitation during the remainder of Thursday; some moisture will remain in the lower levels, causing partly to mostly cloudy conditions.

Conditions will wane overnight with mostly clear skies anticipated for Friday morning. Warming air temperatures and dew point temperatures near 16°C (60°F) will allow CAPE values in the afternoon to approach 1000 J/kg, providing an environment for possible thunderstorm development. Similar conditions are likely for Sunday, and may bring a chance for isolated showers in the early afternoon once again.