By Doug Schneider

Here's how well I did with the forecast for the Bathurst 12 Hour (I'm doing the temperature verification in Fahrenheit because it is a finer scale than Celsius) :

There's a weather station located just 1.2 km north of the Mount Panorama Circuit pit lane, on the Charles Sturt University campus, and data at the site is easily accessible on the Australia Bureau of Meteorology website. It's always nice to have a weather station that is very close to a track to give representative data to verify the forecast against.

Mount Panorama had beautiful weather for the entire event, and compared to last year's scorcher, temperatures were much more pleasant. The models never wavered in their depictions of the weather pattern through the week leading up to the race, so I was pretty confident in the forecast and never had to make big changes from one update to the next. That's a good feeling.

I did have a chance of showers mentioned on Saturday, and while there was no rain recorded at the track or the weather station that day, there were scattered showers around the Bathurst area that just avoided the track. As I mentioned in the posts, showers developed over the Blue Mountains and were able to track into the Bathurst area in the afternoon. So the 30% to 40% chance of showers in the forecast was fairly representative of what happened. A little more cloud cover than expected on Friday and a little less cloud cover on Saturday were probably why I missed the high temperatures those days by 3 to 5 degrees. 

Overall, I'm happy with how the forecast turned out, especially considering the challenge of forecasting for the Southern Hemisphere. 

By Doug Schneider

Let's take a look back at how well the forecast for the Rolex 24 verified.

The forecast did well in the most important area - the precipitation forecast. The initial forecast on 1/21 mentioned a few sprinkles or a brief light shower were possible on Saturday night and Sunday morning, which is exactly what occurred. Only a trace of rain was reported at the airport from a small shower around 8 pm that lasted about 10 minutes. That initial forecast was uncertain about the timing of heavy rain, but the two later forecasts mentioned that heavy rain appeared likely to hold off until after the race ended. There were some periods of sprinkles Sunday morning, but heavy rain wasn't reported at the airport until 6:50 pm. I'm very pleased with how the forecast worked out. 

The low temperature forecast didn't work out as well on Thursday night and Friday night, but I don't think anyone will be too critical for missing the overnight temperatures that were warmer than forecast. I suspect the reason that temperatures stayed so mild overnight was that the wind each night stayed up, between 8 and 14 mph. Calm winds allow for the temperatures to drop lower than when winds stay up. The low temperature forecast Saturday night during the race was good, which was probably the most important night to get right.

There was more sunshine on Sunday than I expected, which allowed temperatures to rise to 77 degrees that afternoon, about 4 to 5 degrees higher than forecast.

By Scott Martin - @RaceWx4You

As you can see by the graphic above, there is a lot of green on the spreadsheet. That means that I was able to correctly forecast the weather conditions with a degree or two, and correctly forecast the rain chances. As for the temperatures on Saturday that were so far off, this time I believe I can blame underperforming forecast models. Both forecast models that I used underestimated the warm air that was able to flow in ahead of the approaching system on Sunday. With a combination of mostly clear skies, temperatures made it into the mid 80s. But I feel good about that because nearly every other trusted weather source that I compare my forecast to also had temperatures at least 5 degrees cooler as well. No one thought it would be 80 degrees or warmer.

I think most people would agree that the yellow showing up for Sunday's rain chances is a great thing. I had a gut feeling throughout the week we would have some rain at or around St. Petersburg on Sunday, but I thought at least some drops would fall. The racing action was able to compete with dry conditions, and fans didn't have to worry about how to stay dry. Good news is that the showers all developed well inland over the Florida Peninsula, and had no worries at all about rain approaching.

I believe most would agree with me that this forecast went pretty well. I am okay with missing the precipitation forecast for Sunday because of the uncertainty to where showers would develop. I don't feel too bad about the temperature miss for Saturday, because everyone missed it due to underperforming models. I will always strive to be better with every forecast that I do, not only with Racecast Weather, but in my day job as well. It's almost impossible to have a perfect forecast, but that is what we try to do.

By Doug Schneider

It's time to take a look back and see how well I did with the forecasts for the Rolex 24 Hours of Daytona. 

If you're not familiar with how forecasts are verified in the spreadsheet below, here's a quick summary - the two top rows show the temperatures and precipitation that was observed at the Daytona airport, just behind the Speedway backstretch. The rows below that show the forecast temperature and PoP (Probability of Precipitation) each day that I made a new forecast. The columns with the dates are for each day and night period during the event, Thursday through Sunday. Day is defined as 7 am to 7 pm. The colors in the boxes show how far off my forecast was from what was observed, with the color legend at the bottom. 

By Doug Schneider

Mid-Ohio was one of those events where I felt like I make a pretty good forecast overall, but when I look at the numbers for verification, it doesn't look very good.
 
A big reason for that is how we verify precipitation. In forecasting, rain only counts if you can measure it to the closest hundredth of an inch. Sometimes you'll feel some raindrops, but it won't be enough to measure 0.01 inches. In that case, it is considered a trace (T), and it is counted the same as if it didn't rain. 

By Doug Schneider

The forecast for the 100th Indianapolis 500 was a mixed bag of hits and misses. The general pattern throughout the events was a southerly flow of warm, moist air that provided weak instability and hit-or-miss showers each day. There wasn't a well-defined low pressure system or front that moved across the area to provide organized showers and thunderstorms, which is part of what made the precipitation forecast difficult. I knew there would be some showers around each day, but the question was whether they would hit the Speedway. Given the weather pattern, fans at the Speedway were very fortunate to dodge most of the showers through the event.

​Showers and thunderstorms rolled through Speedway in the early afternoon on Thursday, producing around a quarter inch of rain. The early arrival of the rain kept temperatures in the 70s all day, a little cooler than forecast. Friday turned out to be a dry day, and my 50% rain chance was definitely too high. The abundant sunshine on Friday raised temperatures into the mid 80s, a bit above my initial forecasts. There were some showers around central Indiana on Saturday, but they managed to just avoid the Speedway. A trace of rain was recorded at the airport on Saturday. In retrospect, a 50-60% rain chance in the forecast was probably on the high side, but at least there was some rain in the area.

​​The Indy 500 on Sunday was SO close to being interrupted by thunderstorms. Around 2 pm, a thunderstorm passed just a few miles north of the Speedway. While there was an extended caution flag period for light sprinkles, the weather didn't cause any problems or significant delays, as I had been expecting. But it was very, very close. I was sweating it out there for a while, keeping one eye on radar and one on the race. 

​For the month of June, Scott will be busy preparing the forecasts at all the Road America events as part of our partnership with them. I'll be forecasting for the rest of the events on our schedule, including Le Mans. 

By Scott Martin

The forecast for this past weekend's races at Phoenix International Raceway was very close to being right on the money. In our verification process, we go back and examine where we missed on our temperatures and precipitation chances.

For this event, rain was not even mentioned in the forecast, except for wen I said "no chance of rain." Therefore, 11/11 for the score on precipitation.

In my forecast, I sad that a high-amplitude ridge would build over the western United States and would allow for temperatures to rise quickly during the daylight hours and be well above normal for this time of year. On my forecast for Tuesday, I was a little ambitious on the strength of that ridge and decided to go a degree or two warmer than what the models had. I should have stayed with the models like I did for the rest of the week. Out of 22 forecasted temperatures (11 highs and 11 6PM temperatures), I only missed a total of five by three degrees. Therefore, 17/22 for the score on temperatures.

For this event, I scored a 29/33, or 88%. That's a pretty decent forecast, but it could have been better. Until every one of those boxes are green, there will always be a need to improve.

Doug has your forecast for this week's Trans Am action at Road Atlanta. I'll be back the following week with Indycar and PWC action in Long Beach. Have a great week.

By Doug Schneider

The forecast for Sebring worked out really well, with the rain on race day predicted the Sunday before the race with a 50% PoP. Friday ended up being dry, but I had only a low chance PoP in the forecast a few days earlier. Forecast high temperatures were never off by more than 5 degrees. The timing of the arrival of the rain on Saturday was forecast pretty well, as my Thursday forecast update mentioned that Saturday afternoon and evening would have the best chances of rain. The race day forecast targeted the arrival of the main area of heavy rain and lightning between 1 and 2 pm, which verified well. A brief shower arrived around 12:30, with the first lightning strike within 8 miles occurring around 12:50, with the main area of storms that stopped the race arriving around 2 pm. Forecasting rainfall amounts in Florida is always a challenge due to the often hit-or-miss nature of the thunderstorms and heavy rain, and amounts can vary wildly over short distances. I was expecting somewhere between a quarter and a half inch of rain, with more possible within stronger storms, and there ended up being 0.74" at a nearby observation site. Some other sites a little farther from the track got over one inch.

The Storm Prediction Center issued a Severe Thunderstorm Watch near Sebring at 1:15 pm, mentioning a potential threat of damaging wind gusts and large hail. While the highest gust I saw at nearby observation sites was around 20 mph, there was some wind damage east of Lake Okeechobee, and even a tornado near Fort Lauderdale. Thankfully, it sounds like everyone at the track was safe and there was no significant damage.

I applaud IMSA for doing their part in keeping the drivers, teams, and track marshals safe from the hazardous weather. They red flagged the race before the frequent lightning arrived at the track. The TV crews were brought down from their scaffolding as soon as lightning was observed nearby. However, it sounds like safety efforts for the fans were lacking in some respects.

I asked some fans who were at the race how they were informed of the approaching weather and the need to take shelter. I received mixed responses. Katie Mech said she was only notified by a text message from a friend. Michael Goodwin said he was notified through the Radio Le Mans broadcast, but not through the PA system. Charley Robertson was notified by the Corvette Car Corral. The fans who replied to me via Facebook mentioned that they were well informed of the situation by PA announcements and the radio broadcast. Others were notified by police officers of the approaching storms (see comment on this post). So it seems that some fans got a message from the track officials, but others did not. Vickie Miller told me that the PA speakers at the track are few and far between, and often cannot be heard when cars are on track. Both Katie and Vickie said that there were no messages on the video screens to alert fans to seek shelter - only a weather map was displayed. And police officers can't reach every person. So whether the message was heard probably depended on where fans were located and whether they were listening to the radio broadcast at the time. Vickie summed up the PA message that she heard this way:

​I noticed that there was one Tweet sent from Sebring Raceway that mentioned the hazardous weather: 

This tweet was sent more than half an hour after the Severe Thunderstorm Watch was issued, and about one hour after the first lightning strike occurred within 8 miles of the track. 

From the information I've gathered, the track could have done a better job of communicating the threat to the fans and keeping them informed. There's no excuse for the lack of a message on video screens. A video message is important as the PA system often can't be heard over the sound of the cars. In addition, social media could have been used more effectively. In my interview with other tracks about their hazardous weather policies, I learned that social media is an important channel for tracks to get messages out to fans. There were many tweets from myself, Scott, and from others about the approaching weather well in advance, several of which tagged the track, but the track's official Twitter account was silent until this tweet. ​Sending out one tweet an hour after the threat first become imminent is not enough. Vickie told me that she used Twitter frequently at Sebring to get weather information, and she found it very helpful to know where the rain was located. There wasn't much effort from Sebring Raceway to keep fans informed and help direct fans to safety. There aren't many places at Sebring to find shelter, but at a minimum, they could have retweeted me: