Will today be a good/average/bad day for solar pv energy?

I am using the Forecast.Solar integration and looking at the ‘Solar production forecast Estimated energy production - tomorrow’ sensor but don’t understand the data. On a graph there are many (24?) data points in each 24 hour period. There can be considerable differences between the values of adjacent data points. What is each data point telling me? From the typical values of the data points I think each is a forecast of the total energy production tomorrow. Right? What does the variability of the data tell me?

The time period for a day’s first forecast covers 24hrs - 48hrs in the future. The time period for a day’s last forecast covers 0hrs - 24hrs in the future. Does the accuracy of the forecast increase as the day progresses?