By: Stephen McCoy

For the past three races of the Rolex 24 hours of Daytona, there’s been periods of rain that have been bothersome to teams, drivers, track officials, and fans. But the rain seen at the 2019 iteration stands out from the previous two years. A veritable deluge of precipitation began in the 4:00-5:00 hour on Sunday and refused to let up, causing IMSA to call the race ten minutes before the conclusion of 24 hours after two red flag periods with multiple full course yellows in between. The question though is why all the rain? What made this year’s weather conditions so different than those seen recently?

To begin, I’ll look at the atmosphere on Saturday night.

By Doug Schneider

The chance of a shower or thunderstorm occurring in the Bathurst area Saturday afternoon looks a little bit higher with the latest model runs. It is still a fairly low chance, just 30%, and if it does occur, I don't expect that it will have a big impact on the racing. Any showers in the area should produce just light and brief rainfall. The chance of lightning in the area is even lower, maybe around 10%, but it can't be ruled out entirely. The timing of any potential showers appears to be around or after 4 pm local time, which may affect the Combined Sedans race and the Top 10 Shootout.

Radar coverage is rather sparse for inland parts of New South Wales, but here's a link to a radar near Sydney.

The weather for the race continues to look dry and warmer, with temperatures at start time in the mid/upper teens C or lower 60s F. With a good amount of sunshine expected, high temperatures will reach the lower 30s C or upper 80s F by the end of the race. 

By Doug Schneider

Today's forecast update for the Bathurst 12 Hour has a few small changes in it compared to my last forecast, but overall, the weather continues to look great for racing.

The expected weather pattern across southern Australia hasn't changed significantly, with a large high pressure area off the southern coast expected to drift eastward through the weekend. This high brings cooler and drier air to New South Wales on Friday. I did raise temperatures a couple degrees for Friday and Saturday from my initial forecast.

The main change with the update was to add a mention of a possible afternoon shower on Saturday, as it appears that there will be just enough instability to allow for some showers to pop up. The best chance of showers will be over the higher terrain of the Blue Mountains, east of Bathurst. With the prevailing wind flow coming from the east, some of these showers that develop over the mountains could push west toward Bathurst late in the day. As you can see in the forecast, the chance of a shower happening at the track is low, only 20%. 

The weather for the race looks great, with comfortable temperatures at the start in the upper teens C or lower 60s F. High temperatures during the race will rise into the lower 30s C or upper 80s F. There will be some cloud cover developing in the afternoon hours, but no rain is expected. 

By Doug Schneider

The first round of the Intercontinental GT Challenge takes place this weekend at the awesome and beautiful Mount Panorama Circuit near Bathurst, Australia. The weather for the entire event looks great.

Thursday will open with warm temperatures in the mid 30s C/ mid 90s F. Then a cold front will pass through the area Thursday night, which will shift winds around to the south. There will not be enough moisture with the front to produce any precipitation. 

High pressure off the southern Australia coast will be building into New South Wales on Friday, and with it will come cooler temperatures and a southeast wind. This high will be drifting east across Tasmania and toward New Zealand through the weekend. As it does, winds will shift back around to a northerly direction, bringing a gradual warming trend each day. By Sunday afternoon for the end of the race, temperatures will be back over 30 C.

One thing to keep an eye on will be the potential for afternoon showers to pop up on Sunday. At this time it seems unlikely, but with warming temperatures and a little more moisture, it can't be ruled out entirely. I'm going with a dry forecast for now, but stay tuned for updates later in the week.

Looking at the latest high resolution models, we could have rain moving into the Daytona Beach area, including the speedway, starting as early as around 3:00 am. Precipitation may start off as a passing light shower or sprinkles, but by 5:00 am, light to moderate rainfall can be expected through the remainder of the race.

We could see rainfall totals around or just over 1/4-inch through noon and possibly another 1/4-in from noon to the checkered flag. Unfortunately, rainfall could be heavy enough to cause a few caution flags, especially after the noon hour. The only good news is that the air will be stable enough for lightning to not occur.

So, here is the break down in times...

9:00 pm:  Mostly cloudy and dry. Around 53 degrees. Winds out of the north-northeast at 5-10 MPH.

12:00 am:  Cloudy and dry. Around 53 degrees. Winds out of the north-northeast at 5-10 MPH.

3:00 am:  Cloudy with a chance of showers. Around 52 degrees. Winds out of the northeast at 5-10 MPH. Chance of rain around 40%.

6:00 am:  Cloudy with rain likely. Around 50 degrees. Winds out of the north-northeast at 10-15 MPH with possible gusts up to 20 MPH. Chance of rain 100%.

9:00 am:  Cloudy with rain likely. Around 53 degrees. Winds out of the north-northeast at 10-15 MPH with possible gusts up to 25 MPH. Chance of rain 100%.

12:00 pm:  Cloudy with rain likely. Around 56 degrees. Winds out of the north at 10-15 MPH with possible gusts up to 30 MPH. Chance of rain 100%.

Checkered Flag:  Cloudy with rain likely. Around 56 degrees. Winds out of the north at 10-20 MPH with possible gusts up to 30 MPH. Chance of rain 100%.

While it is exciting to see the best racers in the world racing in wet conditions, rain may be too hard at times for the race to be put under the caution flag a few times. I'm crossing my fingers that it doesn't get to the point of stopping the cars.

Our radar continues to run on our website. If viewing on a mobile device, it is best to select the "web" view at the bottom of the page. I'll be working on a more web-friendly version throughout the next few weeks.