By Doug Schneider - @Race4caster
The past few days have been a challenge to figure out the timing and amount of rain that can be expected on Sunday. Fortunately, my confidence in Sunday's forecast is higher as the models are coming into better agreement today.
For Friday and Saturday, the forecast hasn't changed much. Friday will start off mostly sunny, but clouds will be increasing through the day. There will probably be more sun than clouds from Friday afternoon through Saturday due to an easterly wind off the ocean. This moisture will be shallow enough that I don't think there will be any rain, at least not until Saturday night. I can't rule out a few sprinkles on Saturday night, but it expect that it would not have an impact on the race.
With Tuesday's update, I showed how two models were showing very different rainfall amounts between 10 am and 4 pm. Here are the same two models, from today's morning run, with their prediction for rainfall in the same period of time:
For Friday and Saturday, the forecast hasn't changed much. Friday will start off mostly sunny, but clouds will be increasing through the day. There will probably be more sun than clouds from Friday afternoon through Saturday due to an easterly wind off the ocean. This moisture will be shallow enough that I don't think there will be any rain, at least not until Saturday night. I can't rule out a few sprinkles on Saturday night, but it expect that it would not have an impact on the race.
With Tuesday's update, I showed how two models were showing very different rainfall amounts between 10 am and 4 pm. Here are the same two models, from today's morning run, with their prediction for rainfall in the same period of time:
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The one on the left (GFS) has Daytona in the 0.12 to 0.2 range, and the one on the right (ECMWF) has Daytona in the 0.04 to 0.08 range. This is much closer than what they were showing on Tuesday, and fortunately, the wetter model on Tuesday (GFS) has become much drier. That gives me confidence that the race, which ends at 2:40 pm, will avoid heavy rain or storms that will cause delays or a stoppage.
Here's an animation of another model, the NAM, and its depiction of rainfall between 7 am and 7 pm (each time step is three hours apart - 7 am, 10 am, 1 pm, 4 pm, and 7 pm):
Here's an animation of another model, the NAM, and its depiction of rainfall between 7 am and 7 pm (each time step is three hours apart - 7 am, 10 am, 1 pm, 4 pm, and 7 pm):
This shows the arrival of light rain at Daytona between 10 am and 1 pm, with between 0.1 and 0.2 inches of rain falling between 10 am and 4 pm. This is right in line with the amount that the other two models above are showing.
So here's what I'm thinking today about what to expect on Sunday - there may be a few sprinkles early in the morning, but not enough to have any significant impact. Light rain showers (more than just sprinkles) are likely to arrive at the track in the mid to late morning, starting between 9 am and noon. Light on/off showers will continue from noon until the end of the race, with the rain getting heavier after the race ends, probably between 3 pm and 6 pm. The amount of rain from the time it starts to the end of the race will likely be between 0.05 and 0.15 inches. If that happens as expected, then the rain tires should be able to handle it, and I don't foresee the race having to be stopped.
There is still 72 hours and several more model runs before we get to Sunday afternoon, so this could change completely before then. But that's what I'm thinking right now. I'll have another update on Saturday at the latest.
So here's what I'm thinking today about what to expect on Sunday - there may be a few sprinkles early in the morning, but not enough to have any significant impact. Light rain showers (more than just sprinkles) are likely to arrive at the track in the mid to late morning, starting between 9 am and noon. Light on/off showers will continue from noon until the end of the race, with the rain getting heavier after the race ends, probably between 3 pm and 6 pm. The amount of rain from the time it starts to the end of the race will likely be between 0.05 and 0.15 inches. If that happens as expected, then the rain tires should be able to handle it, and I don't foresee the race having to be stopped.
There is still 72 hours and several more model runs before we get to Sunday afternoon, so this could change completely before then. But that's what I'm thinking right now. I'll have another update on Saturday at the latest.
